Android 7.0，(N) 相容性定義

目錄

一、簡介

本文檔列舉了裝置與 Android 7.1 相容必須滿足的要求。

「MUST」、「MUST NOT」、「REQUIRED」、「SHALL」、「SHALL NOT」、「SHOULD」、「SHOULD NOT」、「RECOMMENDED」、「MAY」和「OPTIONAL」的使用符合 IETF 標準RFC2119中定義的標準。

在本文檔中，「裝置實施者」或「實施者」是指開發運行 Android 7.1 的硬體/軟體解決方案的個人或組織。 “設備實現”或“實現是這樣開發的硬體/軟體解決方案。

若要被視為與 Android 7.1 相容，裝置實作必須滿足此相容性定義中提出的要求，包括透過引用納入的任何文件。

如果第 10 節中所述的此定義或軟體測試是沉默的、不明確的或不完整的，則設備實現者有責任確保與現有實現的兼容性。

因此， Android 開源專案既是 Android 的參考實現，也是首選實現。強烈建議設備實現者最大程度地基於 Android 開源專案提供的「上游」原始程式碼來實現其實現。雖然假設某些組件可以替換為替代實現，但強烈建議不要遵循這種做法，因為通過軟體測試將變得更加困難。實作者有責任確保與標準 Android 實作完全行為相容，包括相容性測試套件。最後，請注意，本文檔明確禁止某些組件替換和修改。

本文檔中連結的許多資源直接或間接源自 Android SDK，並且在功能上與該 SDK 文件中的資訊相同。在任何情況下，如果本相容性定義或相容性測試套件與 SDK 文件不一致，則 SDK 文件被視為具有權威性。本文檔中連結資源中提供的任何技術細節均被視為本相容性定義的一部分。

2. 設備類型

雖然 Android 開源專案已用於實現各種裝置類型和外形尺寸，但架構和相容性要求的許多方面都針對手持裝置進行了最佳化。從 Android 5.0 開始，Android 開源專案旨在涵蓋本節中所述的更廣泛的裝置類型。

Android 手持裝置是指通常手持使用的 Android 裝置實現，例如 MP3 播放器、手機和平板電腦。 Android 手持裝置實作：

  • 設備中必須嵌入觸控螢幕。
  • 必須有提供移動性的電源，例如電池。

Android TV 裝置是指一種Android 裝置實現，它是一個娛樂介面，用於為坐在大約10 英尺外的用戶消費數位媒體、電影、遊戲、應用程式和/或直播電視（「向後靠」或“10 英尺使用者介面”） ”）。 Android 電視裝置：

  • 必須具有嵌入式螢幕或包含視訊輸出端口，例如 VGA、HDMI 或用於顯示的無線端口。
  • 必須聲明android.software.leanback和 android.hardware.type.television 功能。

Android Watch 裝置是指旨在佩戴在身體上（可能戴在手腕上）的 Android 裝置實現，並且：

  • 螢幕的實體對角線長度必須在 1.1 到 2.5 吋範圍內。
  • 必須聲明 android.hardware.type.watch 功能。
  • 必須支援 uiMode = UI_MODE_TYPE_WATCH 。

Android Automotive 實作是指運行 Android 作為部分或全部系統和/或資訊娛樂功能的作業系統的車輛主機單元。 Android 汽車實現：

  • 螢幕的物理對角線長度必須等於或大於 6 吋。
  • 必須聲明 android.hardware.type.automotive 功能。
  • 必須支援 uiMode = UI_MODE_TYPE_CAR 。
  • Android Automotive 實作必須支援android.car.*命名空間中的所有公用 API。

所有不適合上述任何裝置類型的 Android 裝置實作仍必須滿足本文檔中與 Android 7.1 相容的所有要求，除非該要求明確描述為僅適用於上述特定 Android 裝置類型。

2.1 設備配置

這是按設備類型劃分的硬體配置主要差異的摘要。 （空單元格表示“可以”）。此表並未涵蓋所有配置；有關更多詳細信息，請參閱相關硬體部分。

類別特徵部分手持式電視手錶汽車其他
輸入方向鍵7.2.2.非觸控式導航必須
觸控螢幕7.2.4.觸控螢幕輸入必須必須應該
麥克風7.8.1.麥克風必須應該必須必須應該
感應器加速度計7.3.1 加速度計應該應該應該
全球定位系統7.3.3.全球定位系統應該應該
連接性無線上網7.4.2. IEEE 802.11應該應該應該應該
無線直連7.4.2.1.無線直連應該應該應該
藍牙7.4.3.藍牙應該必須必須必須應該
藍牙低功耗7.4.3.藍牙應該必須應該應該應該
蜂巢式無線電7.4.5。最低網路能力應該
USB週邊/主機模式7.7. USB應該應該應該
輸出揚聲器和/或音訊輸出端口7.8.2.音訊輸出必須必須必須必須

3、軟體

3.1.託管 API 相容性

託管的 Dalvik 字節碼執行環境是 Android 應用程式的主要工具。 Android 應用程式介面 (API) 是向在託管執行時間環境中運行的應用程式公開的一組 Android 平台介面。裝置實作必須提供Android SDK公開的任何記錄的 API 或上游 Android 原始碼中用「@SystemApi」標記修飾的任何 API 的完整實現，包括所有記錄的行為。

裝置實作必須支援/保留由 TestApi 註解 (@TestApi) 標記的所有類別、方法和關聯元素。

設備實作不得省略任何託管 API、更改 API 介面或簽章、偏離記錄的行為或包含無操作，除非本相容性定義明確允許。

此相容性定義允許裝置實作省略 Android 包含的 API 的某些類型的硬體。在這種情況下，API 必須仍然存在並以合理的方式運行。有關此場景的具體要求，請參閱第 7 節。

3.1.1.安卓擴充

Android 支援擴充託管 API，同時保持相同的 API 等級版本。 Android 裝置實作必須預先載入共用程式庫ExtShared和服務ExtServices的 AOSP 實現，其版本高於或等於每個 API 等級允許的最低版本。例如，執行 API 等級 24 的 Android 7.0 裝置實作必須至少包含版本 1。

3.2.軟 API 相容性

除了第 3.1 節中的託管 API 之外，Android 還包括一個重要的僅運行時「軟」API，其形式為意圖、權限和 Android 應用程式的類似方面，這些內容無法在應用程式編譯時強制執行。

3.2.1.權限

設備實現者必須支援並強制執行權限參考頁中記錄的所有權限常數。請注意，第 9 節列出了與 Android 安全模型相關的其他要求。

3.2.2.建構參數

Android API 在android.os.Build 類別中包含許多常數，用於描述目前裝置。為了跨裝置實作提供一致、有意義的值，下表包含裝置實作必須遵守的這些值的格式的附加限制。

範圍細節
版本.發布目前執行的 Android 系統的版本，採用人類可讀的格式。此欄位必須具有7.1中定義的字串值之一。
版本.SDK目前執行的 Android 系統的版本，採用第三方應用程式程式碼可存取的格式。對於 Android 7.1，此欄位必須具有整數值 7.1_INT。
版本.SDK_INT目前執行的 Android 系統的版本，採用第三方應用程式程式碼可存取的格式。對於 Android 7.1，此欄位必須具有整數值 7.1_INT。
版本.增量裝置實現者選擇的值，以人類可讀的格式指定目前正在執行的 Android 系統的特定版本。該值不得重複用於提供給最終用戶的不同建置。此欄位的典型用途是指示使用哪個版本號或原始碼控制變更標識符來產生版本。該欄位的具體格式沒有要求，但不能為 null 或空字串 ("")。
木板設備實現者選擇的值，以人類可讀的格式標識設備使用的特定內部硬體。此欄位的一個可能用途是指示為設備供電的板的特定版本。此欄位的值必須可編碼為 7 位元 ASCII 並符合正規表示式「^[a-zA-Z0-9_-]+$」。
品牌反映最終用戶所知的與設備相關的品牌名稱的值。必須採用人類可讀的格式，並且應該代表設備的製造商或設備銷售的公司品牌。此欄位的值必須可編碼為 7 位元 ASCII 並符合正規表示式「^[a-zA-Z0-9_-]+$」。
支援_ABIS本機程式碼的指令集名稱（CPU 類型 + ABI 約定）。請參閱第 3.3 節。本機 API 相容性。
SUPPORTED_32_BIT_ABIS本機程式碼的指令集名稱（CPU 類型 + ABI 約定）。請參閱第 3.3 節。本機 API 相容性。
SUPPORTED_64_BIT_ABIS本機程式碼的第二指令集（CPU 類型 + ABI 約定）的名稱。請參閱第 3.3 節。本機 API 相容性。
CPU_ABI本機程式碼的指令集名稱（CPU 類型 + ABI 約定）。請參閱第 3.3 節。本機 API 相容性。
CPU_ABI2本機程式碼的第二指令集（CPU 類型 + ABI 約定）的名稱。請參閱第 3.3 節。本機 API 相容性。
裝置設備實現者選擇的值，包含標識硬體功能配置和設備工業設計的開發名稱或代號。此欄位的值必須可編碼為 7 位元 ASCII 並符合正規表示式「^[a-zA-Z0-9_-]+$」。該設備名稱在產品的生命週期內不得更改。
指紋唯一標識此建置的字串。它應該是合理的人類可讀的。它必須遵循以下模板：

$(品牌)/$(產品)/
$(設備):$(版本.發佈)/$(ID)/$(版本.增量):$(類型)/$(標籤)

例如：

acme/我的產品/
mydevice:7.1/LMYXX/3359:userdebug/測試金鑰

指紋不得包含空白字元。如果上述模板中包含的其他字段具有空白字符，則必須在構建指紋中將它們替換為另一個字符，例如下劃線（“_”）字符。此欄位的值必須可編碼為 7 位元 ASCII。

硬體硬體的名稱（來自核心命令列或/proc）。它應該是合理的人類可讀的。此欄位的值必須可編碼為 7 位元 ASCII 並符合正規表示式「^[a-zA-Z0-9_-]+$」。
主持人一個字串，以人類可讀的格式唯一標識建構建構的主機。該欄位的具體格式沒有要求，但不能為 null 或空字串 ("")。
ID設備實現者選擇的標識符，用於引用特定版本，採用人類可讀的格式。該欄位可以與 android.os.Build.VERSION.INCRMENTAL 相同，但應該是一個對於最終用戶區分軟體版本足夠有意義的值。此欄位的值必須可編碼為 7 位元 ASCII 並符合正規表示式「^[a-zA-Z0-9._-]+$」。
製造商產品原始設備製造商 (OEM) 的商品名稱。該欄位的具體格式沒有要求，但不能為 null 或空字串 ("")。
模型設備實現者選擇的值，包含最終使用者已知的設備名稱。此名稱應與設備行銷和銷售給最終用戶時使用的名稱相同。該欄位的具體格式沒有要求，但不能為 null 或空字串 ("")。
產品設備實施者選擇的值，包含特定產品 (SKU) 的開發名稱或程式碼名稱，該產品在同一品牌中必須是唯一的。必須是人類可讀的，但不一定供最終用戶查看。此欄位的值必須可編碼為 7 位元 ASCII 並符合正規表示式「^[a-zA-Z0-9_-]+$」。該產品名稱在產品的生命週期內不得更改。
串口硬體序號，在具有相同型號和製造商的設備之間必須可用且唯一。此欄位的值必須可編碼為 7 位元 ASCII 並符合正規表示式「^([a-zA-Z0-9]{6,20})$」。
標籤由設備實現者選擇的以逗號分隔的標籤列表，可進一步區分建置。此欄位必須具有與三種典型 Android 平台簽章配置相對應的值之一：release-keys、dev-keys、test-keys。
時間表示建構發生時間的時間戳記的值。
類型由設備實現者選擇的值，指定建置的運行時配置。此欄位必須具有與三種典型 Android 運行時配置相對應的值之一：user、userdebug 或 eng。
使用者產生建置的使用者（或自動使用者）的名稱或使用者 ID。該欄位的具體格式沒有要求，但不能為 null 或空字串 ("")。
安全補丁指示建置的安全性修補程式等級的值。它必須表明該構建不會以任何方式受到指定 Android 公共安全公告中描述的任何問題的影響。它必須採用 [YYYY-MM-DD] 格式，與Android 公共安全公告或Android 安全通報中記錄的定義字串相符，例如「2015-11-01」。
基本作業系統表示建置的 FINGERPRINT 參數的值，除 Android 公共安全公告中提供的補丁外，該值與此建置相同。它必須報告正確的值，如果這樣的建置不存在，則報告空字串（“”）。

3.2.3.意圖相容性

3.2.3.1.核心應用意圖

Android 意圖允許應用程式元件向其他 Android 元件請求功能。 Android 上游項目包括被視為核心 Android 應用程式的應用程式列表，這些應用程式實現了多種意圖模式來執行常見操作。 Android 的核心應用程式是：

  • 英式鐘
  • 瀏覽器
  • 日曆
  • 聯絡方式
  • 畫廊
  • 全球搜尋
  • 啟動器
  • 音樂
  • 設定

裝置實作必須包括適當的核心 Android 應用程式或實作由這些核心 Android 應用程式的所有 Activity 或服務元件定義的相同意圖模式的元件，這些核心 Android 應用程式透過android:exported屬性隱式或明確暴露給其他應用程式.

3.2.3.2.意圖解析

由於 Android 是一個可擴展平台，裝置實作必須允許第三方應用程式覆蓋第 3.2.3.1 節中引用的每個意圖模式。上游 Android 開源實作預設允許這樣做；設備實現者不得為系統應用程式對這些意圖模式的使用附加特殊權限，或阻止第三方應用程式綁定到這些模式並承擔對這些模式的控制。該禁止具體包括但不限於停用「選擇器」使用者介面，該介面允許使用者在全部處理相同意圖模式的多個應用程式之間進行選擇。

設備實作必須為使用者提供一個使用者介面來修改意圖的預設活動。

但是，當預設活動為資料 URI 提供更具體的屬性時，裝置實作可以為特定 URI 模式（例如 http://play.google.com）提供預設活動。例如，指定資料 URI「http://www.android.com」的意圖過濾器模式比瀏覽器的「http://」核心意圖模式更具體。

Android 還包含一種機制，供第三方應用程式為某些類型的 Web URI 意圖聲明權威的預設應用程式連結行為。當在應用程式的意圖過濾器模式中定義此類權威聲明時，設備實作：

  • 必須嘗試透過執行數位資產連結規範中定義的驗證步驟來驗證任何意圖過濾器，這些步驟由上游 Android 開源專案中的套件管理器實作。
  • 必須在應用程式安裝期間嘗試驗證意圖過濾器，並將所有成功驗證的 UIR 意圖過濾器設定為其 UIR 的預設應用程式處理程序。
  • 如果成功驗證但其他候選 URI 過濾器驗證失敗，則可以將特定 URI 意圖過濾器設定為其 URI 的預設應用程式處理程序。如果裝置實作這樣做，它必須在設定選單中為使用者提供適當的每 URI 模式覆蓋。
  • 必須在設定中為使用者提供每個應用程式的應用程式連結控件，如下所示：
    • 使用者必須能夠全面覆蓋應用程式的預設應用程式連結行為：始終打開、始終詢問或從不打開，這必須同樣適用於所有候選 URI 意圖過濾器。
    • 使用者必須能夠看到候選 URI 意圖過濾器的清單。
    • 設備實作可以為使用者提供基於每個意圖過濾器覆蓋已成功驗證的特定候選 URI 意圖過濾器的能力。
    • 如果裝置實作允許某些候選 URI 意圖過濾器成功驗證，而其他一些可能失敗，則裝置實作必須為使用者提供檢視和覆寫特定候選 URI 意圖過濾器的能力。

3.2.3.3.意圖命名空間

裝置實作不得包含任何使用 ACTION、CATEGORY 或 android.xml 檔案中的其他鍵字串來支援任何新意圖或廣播意圖模式的 Android 元件。或com.android。命名空間。裝置實現者不得包含任何使用 ACTION、CATEGORY 或屬於另一個組織的套件空間中的其他關鍵字串來遵循任何新意圖或廣播意圖模式的 Android 元件。設備實現者不得更改或擴展第 3.2.3.1 節中列出的核心應用程式使用的任何意圖模式。設備實作可以包括使用與其自己的組織明確相關的命名空間的意圖模式。該禁止類似於3.6 節中針對 Java 語言類別指定的禁止。

3.2.3.4.廣播意圖

第三方應用程式依靠平台廣播某些意圖，以通知它們硬體或軟體環境的變化。 Android 相容裝置必須廣播公共廣播意圖以回應適當的系統事件。 SDK 文件中描述了廣播意圖。

3.2.3.5.預設應用程式設定

Android 包含的設定可讓用戶輕鬆選擇預設應用程序，例如主螢幕或簡訊。在有意義的情況下，設備實作必須提供類似的設定選單，並與 SDK 文件中所述的意圖過濾器模式和 API 方法相容，如下所示。

設備實現：

3.3.本機 API 相容性

本機程式碼相容性具有挑戰性。因此，強烈建議裝置實現者使用來自上游 Android 開源專案的下列程式庫的實作。

3.3.1.應用程式二進位接口

託管 Dalvik 字節碼可以呼叫應用程式 .apk 檔案中提供的本機程式碼，作為針對適當裝置硬體架構編譯的 ELF .so 檔案。由於本機程式碼高度依賴底層處理器技術，Android 在 Android NDK 中定義了許多應用程式二進位介面 (ABI)。裝置實作必須與一個或多個定義的 ABI 相容，並且必須實現與 Android NDK 的兼容性，如下所示。

如果裝置實作包含對 Android ABI 的支持，則：

  • 必須支援在託管環境中執行的程式碼，以使用標準 Java 本機介面 (JNI) 語義呼叫本機程式碼。
  • 必須與下面列表中每個所需的庫來源相容（即標頭相容）和二進位相容（對於 ABI）。
  • 如果支援任何 64 位元 ABI，則必須支援等效的 32 位元 ABI。
  • 必須透過 android.os.Build.SUPPORTED_ABIS、android.os.Build.SUPPORTED_32_BIT_ABIS 和 android.os.Build.SUPPORTED_64_BIT_ABIS 參數準確報告裝置支援的本機應用程式二進位介面 (ABI)，每個清單都是逗號分隔的ABI 按從最受青睞到最不受青睞的順序排列。
  • 必須透過上述參數僅報告最新版本的Android NDK ABI 管理文件中記錄和描述的 ABI，並且必須包括對高級 SIMD （又稱 NEON）擴展的支援。
  • 應使用上游 Android 開源專案中提供的源代碼和頭文件進行構建

請注意，Android NDK 的未來版本可能會引入對其他 ABI 的支援。如果設備實作與現有的預定義 ABI 不相容，則它根本無法報告對任何 ABI 的支援。

以下本機程式碼 API 必須可用於包含本機程式碼的應用程式：

  • libandroid.so（原生 Android 活動支援）
  • libc（C 庫）
  • libcamera2ndk.so
  • libdl（動態連結器）
  • libEGL.so（原生 OpenGL 表面管理）
  • libGLESv1_CM.so (OpenGL ES 1.x)
  • libGLESv2.so（OpenGL ES 2.0）
  • libGLESv3.so (OpenGL ES 3.x)
  • libicui18n.so
  • 庫克庫克
  • libjnigraphics.so
  • liblog（Android 日誌記錄）
  • libmediandk.so（原生媒體 API 支援）
  • libm（數學庫）
  • libOpenMAXAL.so（OpenMAX AL 1.0.1 支援）
  • libOpenSLES.so（OpenSL ES 1.0.1 音訊支援）
  • libRS.so
  • libstdc++（對 C++ 的最低支援）
  • libvulkan.so（Vulkan）
  • libz（Zlib 壓縮）
  • JNI介面
  • 支援 OpenGL，如下所述

對於上面列出的本機庫，設備實作不得新增或刪除公共函數。

上面未列出但在 AOSP 中實作和提供的本機程式庫作為保留的系統函式庫，不得暴露給針對 API 等級 24 或更高等級的第三方應用程式。

設備實作可以添加非 AOSP 庫並將它們直接作為 API 公開給第三方應用程序，但附加庫應該位於/vendor/lib或/vendor/lib64中，並且必須列在/vendor/etc/public.libraries.txt 。

請注意，裝置實作必須包含 libGLESv3.so，並且必須匯出 NDK 版本 android-24 中定義的所有 OpenGL ES 3.1 和Android 擴充包函數符號。儘管所有符號都必須存在，但只有裝置實際支援的 OpenGL ES 版本和擴充功能的相應功能必須完全實作。

3.3.1.1.圖形庫

Vulkan是一種低開銷、跨平台的 API，用於高效能 3D 圖形。設備實現，即使不包括對 Vulkan API 的支持，也必須滿足以下要求：

  • 它必須始終提供一個名為libvulkan.so的本機庫，該庫導出核心 Vulkan 1.0 API 的函數符號以及VK_KHR_surface 、 VK_KHR_android_surface和VK_KHR_swapchain擴充功能。

設備實作（如果包括 Vulkan API 支援）：

  • 必須透過vkEnumeratePhysicalDevices呼叫報告一個或多個VkPhysicalDevices 。
  • 每個枚舉的VkPhysicalDevices必須完全實作 Vulkan 1.0 API。
  • 必須報告正確的PackageManager#FEATURE_VULKAN_HARDWARE_LEVEL和PackageManager#FEATURE_VULKAN_HARDWARE_VERSION功能標誌。
  • 必須透過libvulkan.so中的vkEnumerateInstanceLayerProperties和vkEnumerateDeviceLayerProperties函式列舉應用程式包的本機函式庫目錄中名為libVkLayer*.so的本機函式庫中包含的層
  • 不得列舉應用程式套件外部的程式庫提供的層，或提供其他追蹤或攔截 Vulkan API 的方法，除非應用程式具有android:debuggable=”true”屬性。

設備實作（如果不包括 Vulkan API 支援）：

3.3.2. 32 位元 ARM 本機程式碼相容性

ARMv8 架構棄用了多個 CPU 操作，包括現有本機程式碼中使用的一些操作。在 64 位元 ARM 裝置上，透過本機 CPU 支援或透過軟體模擬，以下已棄用的操作必須對 32 位元本機 ARM 程式碼保持可用：

  • SWP 和 SWPB 指令
  • 設定指令
  • CP15ISB、CP15DSB 和 CP15DMB 屏障操作

舊版 Android NDK 使用 /proc/cpuinfo 從 32 位元 ARM 本機程式碼發現 CPU 功能。為了與使用此 NDK 建置的應用程式相容，當 32 位元 ARM 應用程式讀取 /proc/cpuinfo 時，裝置必須在 /proc/cpuinfo 中包含以下行：

  • “功能：”，後面是裝置支援的任何可選 ARMv7 CPU 功能的清單。
  • “CPU 架構：”，後面跟著一個整數，描述裝置支援的最高 ARM 架構（例如，“8”表示 ARMv8 裝置）。

這些要求僅在 32 位元 ARM 應用程式讀取 /proc/cpuinfo 時適用。當 64 位元 ARM 或非 ARM 應用程式讀取 /proc/cpuinfo 時，裝置不應變更。

3.4.網路相容性

3.4.1.網頁視圖相容性

Android Watch 裝置可以，但所有其他裝置實作必須提供 android.webkit.Webview API 的完整實作。

平台功能 android.software.webview 必須在提供 android.webkit.WebView API 完整實作的任何裝置上報告，且不得在沒有完整 API 實作的裝置上報告。 Android 開源實作使用 Chromium 專案中的程式碼來實作android.webkit.WebView 。由於為 Web 渲染系統開發全面的測試套件是不可行的，因此設備實作者必須在 WebView 實作中使用 Chromium 的特定上游版本。具體來說：

  • 裝置 android.webkit.WebView 實作必須基於 Android 7.1 上游 Android 開源專案的Chromium建置。此版本包括一組針對 WebView 的特定功能和安全性修復。

  • WebView 報告的用戶代理字串必須採用以下格式：

    Mozilla/5.0（Linux；Android $(VERSION)；$(MODEL) Build/$(BUILD)；wv) AppleWebKit/537.36（KHTML，如 Gecko）版本/4.0 $(CHROMIUM_VER) Mobile Safari/537.36

    • $(VERSION) 字串的值必須與 android.os.Build.VERSION.RELEASE 的值相同。
    • $(MODEL) 字串的值必須與 android.os.Build.MODEL 的值相同。
    • $(BUILD) 字串的值必須與 android.os.Build.ID 的值相同。
    • $(CHROMIUM_VER) 字串的值必須是上游 Android 開源專案中 Chromium 的版本。
    • 設備實作可以在用戶代理字串中省略 Mobile。

WebView元件應包括對盡可能多的HTML5功能的支持，並且如果支持該功能，則該功能應符合HTML5規範。

3.4.2。瀏覽器相容性

Android電視，手錶和Android汽車實作可能會忽略瀏覽器應用程序，但必須支援第3.2.3.1節所述的公共意圖模式。所有其他類型的設備實作都必須包含一個獨立的瀏覽器應用程序，以用於一般使用者網頁瀏覽。

獨立的瀏覽器可能基於WebKit以外的瀏覽器技術。但是，即使使用了替代瀏覽器應用程序，也必須基於WebKit，android.webkit.webview元件必須基於WebKit，如第3.4.1節所述。

實作可以在獨立瀏覽器應用程式中運送自訂使用者代理字串。

獨立的瀏覽器應用程式（無論是基於上游WebKit瀏覽器應用程式還是第三方更換），應包括對盡可能多的HTML5的支援。最少，設備實作必須支援與HTML5關聯的每個API：

此外，設備實作必須支援HTML5/W3C WebStorage API ，並應支援HTML5/W3C索引EDDB API 。請注意，隨著Web開發標準機構正在過渡以偏好索引dexedDB而不是WebStorage，因此索引EDEXEDDB有望成為未來版本的Android所需的元件。

3.5. API行為相容性

每種API類型（託管，軟，本地和Web）的行為必須與上游Android開源專案的首選實作一致。相容性的一些特定領域是：

  • 設備不得改變標準意圖的行為或語意。
  • 設備不得改變特定類型的系統元件的生命週期或生命週期語意（例如服務，活動，content -provider等）。
  • 設備不能更改標準許可的語意。

上面的列表並不全面。相容性測試套件（CTS）測試了行為相容性平台的重要部分，但不是全部。實施者有責任確保與Android開源專案的行為相容性。因此，設備實施者應在可能的情況下使用Android開源專案可用的原始程式碼，而不是重新實作系統的重要部分。

3.6. API名稱空間

Android遵循Java程式語言定義的軟體包和類別名稱空間約定。為了確保與第三方應用程式的相容性，設備實施者不得對這些軟體包名稱空間進行任何禁止的修改（請參見下文）：

  • Java。*
  • Javax。*
  • 太陽。*
  • 安卓。*
  • com.android。*

禁止的修改包括：

  • 裝置實作不得透過更改任何方法或類別簽署或刪除類別或類別欄位來修改Android平台上公開曝光的API。
  • 設備實施者可以修改API的基本實現，但是此類修改不得影響任何公開暴露的API的既定行為和Java語言簽章。
  • 設備實作者不得在上面的API中添加任何公開暴露的元素（例如類，介面或欄位或方法）。

「公開暴露的元素」是任何未用上游Android原始碼中使用的「 @Hide」標記裝飾的構造。換句話說，裝置實現者不得在上述名稱空間中揭示新的API或更改現有的API。設備實現者可能會進行僅內部修改，但不得對開發人員進行廣告或以其他方式進行廣告宣傳。

裝置實作者可能會新增自訂API，但任何此類API都不得在另一個組織擁有或參考另一個組織的命名空間中。例如，裝置實現者不得將API新增至com.google。*或類似的名稱空間：只有Google可以這樣做。同樣，Google不得將API加入其他公司的名稱空間。此外，如果裝置實作包含標準Android名稱空間以外的自訂API，則必須將這些API包裝在Android共用程式庫中，以便只有明確使用它們的應用程式（透過<susta-use-library>機制）增加的記憶體使用的影響這樣的API。

如果設備實現者建議改進上面的一個軟體包名稱空間（例如，透過在現有API中添加有用的新功能或添加新API），則該實施者應訪問source.android.com ，並開始貢獻更改和貢獻更改的過程根據該網站上的信息，程式碼。

請注意，上述限制對應於Java程式語言命名API的標準約定；本節僅旨在加強這些慣例，並透過包含在此相容性定義中使它們具有約束力。

3.7.運行時相容性

設備實作必須支援完整的Dalvik可執行檔（DEX）格式和Dalvik字節碼規範和語意。設備實現者應使用ART，DALVIK可執行格式的參考上游實現以及參考實現的軟體包管理系統。

設備實作必須配置Dalvik Runtimes，以根據上游Android平台分配內存，並按照下表規定。 （有關螢幕尺寸和螢幕密度定義，請參閱第7.1.1節。）請注意，下面指定的記憶體值被視為最小值，裝置實作可能分配每個應用程式的更多記憶體。

螢幕佈局螢幕密度最小應用記憶
Android手錶120 DPI（LDPI） 32MB
160 DPI（MDPI）
213 DPI（TVDPI）
240 DPI（HDPI） 36MB
280 DPI（280DPI）
320 DPI（XHDPI） 48MB
360 DPI（360DPI）
400 DPI（400DPI） 56MB
420 DPI（420DPI） 64MB
480 dpi（xxhdpi） 88MB
560 DPI（560DPI） 112MB
640 DPI（xxxhdpi） 154MB
小/正常120 DPI（LDPI） 32MB
160 DPI（MDPI）
213 DPI（TVDPI） 48MB
240 DPI（HDPI）
280 DPI（280DPI）
320 DPI（XHDPI） 80MB
360 DPI（360DPI）
400 DPI（400DPI） 96MB
420 DPI（420DPI） 112MB
480 dpi（xxhdpi） 128MB
560 DPI（560DPI） 192MB
640 DPI（xxxhdpi） 256MB
大的120 DPI（LDPI） 32MB
160 DPI（MDPI） 48MB
213 DPI（TVDPI） 80MB
240 DPI（HDPI）
280 DPI（280DPI） 96MB
320 DPI（XHDPI） 128MB
360 DPI（360DPI） 160MB
400 DPI（400DPI） 192MB
420 DPI（420DPI） 228MB
480 dpi（xxhdpi） 256MB
560 DPI（560DPI） 384MB
640 DPI（xxxhdpi） 512MB
超大120 DPI（LDPI） 48MB
160 DPI（MDPI） 80MB
213 DPI（TVDPI） 96MB
240 DPI（HDPI）
280 DPI（280DPI） 144MB
320 DPI（XHDPI） 192MB
360 DPI（360DPI） 240MB
400 DPI（400DPI） 288MB
420 DPI（420DPI） 336MB
480 dpi（xxhdpi） 384MB
560 DPI（560DPI） 576MB
640 DPI（xxxhdpi） 768MB

3.8.使用者介面相容性

3.8.1.發射器（主螢幕）

Android包括啟動器應用程式（主畫面）和支援第三方應用程式以取代裝置啟動器（主畫面）。允許第三方應用程式更換裝置主畫面的裝置實作必須聲明平台功能Android.software.home_screen。

3.8.2.小部件

小部件對於所有Android裝置實作都是可選的，但應在Android手持裝置上支援。

Android定義了元件類型和相應的API和生命週期，該類型允許應用程式向最終用戶展示「 AppWidget」 ，這是強烈建議在手持裝置實作上支援的功能。支援將小部件嵌入主畫面上的裝置實作必須滿足以下要求並聲明對平台功能android.software.app_widgets的支援。

  • 設備啟動器必須包含對AppWidgets的內建支持，並揭示直接在啟動器中直接添加，配置，查看和刪除AppWidgets的使用者介面。
  • 設備實作必須能夠渲染標準網格大小中4 x 4的小工具。有關詳細信息，請參見Android SDK文件中的應用程式小工具設計指南。
  • 包括鎖定螢幕的支援的裝置實作可以支援鎖定螢幕上的應用程式小工具。

3.8.3。通知

Android包含API，讓開發人員使用裝置的硬體和軟體功能將著名事件通知使用者。

一些API允許應用程式執行通知或使用硬體（特定聲音，振動和光線）引起注意。設備實作必須支援使用硬體功能的通知，如SDK文件中所述，並在設備實現硬體的範圍內。例如，如果裝置實作包括振動器，則必須正確實作振動API。如果設備實現缺乏硬件，則必須將相應的API實作為無操作。在第7節中進一步詳細介紹了這種行為。

此外，該實作必須正確渲染API中提供的所有資源（圖標，動畫檔案等），或在狀態/系統欄圖標樣式指南中，在Android電視裝置的情況下，該指南包括可能不顯示該裝置通知。設備實施者可以為通知提供替代使用者體驗，而不是參考Android開源實作。但是，此類替代通知系統必須如上所述支援現有的通知資源。

Android Automotive實現可以管理通知的可見性和時間，以減輕駕駛員的注意力，但必須在應用程式要求時顯示使用Carextender的通知。

Android包括對各種通知的支持，例如：

  • 豐富的通知。持續通知的互動視圖。
  • 主題通知。互動式視圖使用者可以在不留下當前應用程式的情況下採取行動或解散。
  • 鎖定螢幕通知。在鎖定螢幕上顯示的通知具有可見性的顆粒狀控制。

Android裝置實作（當使此類通知都可見時，必須正確執行富富票，並在Android API中記錄的標題/名稱，圖標，文字。

Android包括通知偵聽器服務API，該API允許應用程式（一旦用戶明確啟用了）在發布或更新時會收到所有通知的副本。裝置實作必須正確且迅速將通知完整傳送至所有此類安裝和啟用使用者的偵聽器服務，包括附加到Notification物件的所有元資料。

手持裝置的實作必須支援本節所述的更新，刪除，回覆和捆綁通知的行為。

此外，手持設備實施必須提供：

  • 直接在通知陰影中控制通知的能力。
  • 視覺負擔能力觸發通知陰影中的控制面板。
  • 在內聯控制面板和設定應用程式中，可以阻止，靜音和重置通知偏好的能力。

Notification.Style class的所有6個直接子類別。式類別必須如SDK文件中所述支援。

支援DND的裝置實現（請勿打擾）功能必須符合以下要求：

  • 必須實施一項將響應意圖action_notification_policy_access_settings的活動，該活動對於使用UI_MODE_TYPE_Normal實現，它必須是一項活動，用戶可以在其中授予或拒絕應用程式存取DND策略配置的活動。
  • 必須，如果裝置實現為使用者提供了授予或拒絕第三方應用程式存取DND策略配置的手段時，請顯示由應用程式建立的自動DND規則以及使用者建立的和預先定義的規則。
  • 必須兌現沿NotificationManager.Policy的suppressedVisualEffects值，並且如果應用程式設定了任何dustresse_effect_screen_off或dustressed_effect_effect_screen_on flags，則應向使用者表明視覺效果在DND設定選單中受到抑制。

Android包含API，使開發人員可以將搜尋納入其應用程式中，並將其應用程式的資料曝光到全球系統搜尋。一般而言，此功能由一個單一的，全系統的使用者介面組成，該介面允許使用者輸入查詢，將建議顯示為使用者類型並顯示結果。 Android API允許開發人員重複使用此介面以在自己的應用程式中提供搜索，並允許開發人員為常見的全域搜尋使用者介面提供結果。

Android設備實現應包括全局搜索，一個單一，共享的，系統範圍的搜索用戶界面，能夠響應用戶輸入來實時建議。設備實作應實作API，允許開發人員重複使用此使用者介面以在自己的應用程式中提供搜尋。實現全域搜尋介面的裝置實作必須實作允許第三方應用程式以在全域搜尋模式運行時將建議新增至搜尋框的API。如果未安裝使用此功能的第三方應用程序，則預設行為應顯示Web搜尋引擎結果和建議。

Android裝置的實作應（Android Automotive實作）必須在裝置上實施助理來處理輔助操作。

Android還包括輔助API ，以允許應用程式選擇與裝置上的助理共享目前上下文的多少資訊。當透過在螢幕邊緣周圍顯示白光時，支援輔助操作的裝置實作必須向最終使用者明確指示。為了確保對最終用戶的清晰可見性，指示必須滿足或超過Android開源專案實施的持續時間和亮度。

如果滿足所有以下要求，則預設情況下可以透過預設使用預先安裝的應用程式來停用此指示：

  • 預先安裝的應用程式必須要求上下文僅在使用者以以下方式呼叫應用程式時共享上下文，並且該應用程式在前景中運行：

    • 熱詞調用
    • 輔助導航鍵/按鈕/手勢的輸入

  • 設備實現必須提供負擔能力以啟用指示，距離（預設語音輸入和助理應用程式設定選單）少於兩個導航範圍3.2.3.3.5 。

3.8.5。吐司

應用程式可以使用“ Toast” API向最終用戶顯示短時間以後消失的簡短非模式字串。設備實現必須以某種高可見性顯示從應用程式到最終用戶的吐司。

3.8.6。主題

Android提供了「主題」作為應用程式在整個活動或應用程式中應用樣式的機制。

Android包括一個「 Holo」主題家族，作為一組定義樣式，供應用程式開發人員使用Android SDK定義的Holo主題外觀和感覺，以便使用。設備實作不得更改暴露於應用程式的任何Holo主題屬性。

Android包括一個“材料”主題家族，作為一組定義樣式，如果應用程式開發人員想在各種不同的Android設備類型中匹配設計主題的外觀和感覺，則使用。設備實現必須支援“材料”主題家族，並且不得更改任何材料主題屬性或暴露於應用程式的資產。

Android還包括一個「裝置預設」主題家族，作為一組定義樣式，供應用程式開發人員使用裝置實現者定義的裝置主題的外觀和感覺，以便使用。設備實作可能會修改裝置預設主題屬性暴露於應用程式。

Android用半透明的系統條支援一個變體主題，該主題允許應用程式開發人員用其應用程式內容填充狀態和導航列背後的區域。為了在此配置中啟用一致的開發人員體驗，重要的是，在不同的裝置實作之間保持狀態列圖示樣式。因此，Android裝置的實作必須將白色用於系統狀態圖示（例如訊號強度和電池電量）和系統發出的通知，除非圖示表示有問題的狀態或應用程式要求使用Sytem_UI_FLAG_LIGHT_STATUS_STATUS_BAR FLAG請求燈架列。當應用程式要求輕型狀態列時，Android裝置實作必須將系統狀態圖示的顏色變更為黑色（有關詳細信息，請參閱R.Style ）。

3.8.7。動態壁紙

Android定義了一種元件類型和相應的API和生命週期，該應用程式允許應用程式向最終用戶展示一個或多個「即時桌布」 。即時壁紙是動畫，圖案或類似的圖像，其輸入功能有限，顯示為牆紙，在其他應用程式後面。

如果硬體可以運行所有即時壁紙，則可以可靠地運行即時壁紙，而沒有對功能的限制，以合理的幀速率對其他應用沒有不利影響。如果硬體中的限制導致壁紙和/或應用程式崩潰，故障，消耗過多的CPU或電池電量，或以不可接受的較低幀速率運行，則該硬體被認為無法運行Live Wallpaper。例如，某些即時壁紙可以使用OpenGL 2.0或3.X上下文渲染其內容。實時壁紙不會在不支援多個OpenGL上下文的硬體上可靠地運行，因為OpenGL上下文的即時壁紙使用可能與也使用OpenGL上下文的其他應用程式相抵觸。

如上所述，能夠可靠地運行即時壁紙的設備實現應實現即時壁紙，並且在實施後必須報告平台功能flag android.software.live_wallpaper。

3.8.8。活動切換

由於最新功能導航鍵是可選的，因此實現概述畫面的要求是Android Watch和Android Automotive實現的可選，並建議用於Android電視裝置。仍然應該有一種方法可以在Android汽車實現的活動之間切換。

上游的Android原始碼包括概述螢幕，概述螢幕，一個用於任務切換和顯示最近訪問的活動和任務的系統級用戶介面，使用應用程式圖形狀態的縮圖，當時用戶上次離開應用程式。第7.2.3節所述的設備實作包括Recents功能導航金鑰可能會更改接口，但必須滿足以下要求：

  • 必須至少支援多達20個顯示的活動。
  • 至少應該一次顯示4個活動的標題。
  • 必須實現螢幕固定行為，並為使用者提供設定選單以切換該功能。
  • 應顯示重點，圖標，螢幕標題。
  • 應顯示關閉負擔（“ x”），但可能會延遲此直到使用者與螢幕互動。
  • 應該實現快捷方式以輕鬆切換到先前的活動
  • 可能會顯示關聯的恢復，作為一個一起移動的群組。
  • 應觸發兩個最近使用的應用程式之間的快速開關動作，當Recents函數金鑰被敲擊兩次時。
  • 如果支持，則應觸發分割畫面多風扇模式，如果需要，則應長時間按下RECENTS功能鍵。

強烈建議將設備實作用於概述螢幕上游Android使用者介面（或類似的基於縮圖的介面）。

3.8.9。輸入管理

Android包括支援輸入管理和對第三方輸入方法編輯器的支援。允許使用者在裝置上使用第三方輸入方法的裝置實作必須聲明平台功能android.software.input_methods並支援Android SDK文件中定義的IME API。

聲明Android.software.input_methods功能的裝置實作必須提供可新增和設定第三方輸入方法的使用者存取機制。裝置實作必須根據android.settings.input_method_settings的意圖顯示設定介面。

3.8.10。鎖定螢幕媒體控制

遠端控制用戶端API從Android 5.0中棄用了媒體通知模板，該模板允許媒體應用程式與鎖定螢幕上顯示的播放控制項整合。除非Android Automotive或Watch實現，否則支援鎖定螢幕的裝置實作必須顯示鎖定螢幕通知，包括媒體通知範本。

3.8.11。螢幕保護程式（以前的夢想）

Android包括對InteractivesCreensavers的支持，以前稱為夢。當連接到電源來源的裝置空閒或停靠在桌上碼頭時，螢幕保護程式允許使用者與應用程式互動。 Android Watch裝置可以實現螢幕保護程序，但其他類型的裝置實作應包括對螢幕保護程式的支持，並為使用者提供設定選項，以回應android.settings.DREAM_SETTINGS意圖。

3.8.12。地點

當裝置具有能夠提供位置座標的硬體感測器（例如GPS）時，必須在設定內的位置選單中顯示位置模式。

3.8.13。 Unicode和字體

Android包含對Unicode 9.0中定義的表情符號字元的支援。所有裝置實作都必須能夠在顏色字形中呈現這些表情符號字符，並且當Android裝置實作包括IME時，它應為這些表情符號字元的使用者提供輸入方法。

Android手持裝置應依照Unicode技術報告＃51的指定支援膚色和多樣化的家庭表情符號。

Android包括對具有不同重量的Roboto 2字體的支援-Sans-serif-shin，sans-serif-light，sans-serif-medium，sans sans-serif-black，sans-sers-serif-serif-wondensed，sans- sans-serif-serif-serif-densed-wighted-light-wher必須全部包含在設備上可用的語言和拉丁語，希臘和西里爾的完整Unicode 7.0覆蓋範圍，包括拉丁語擴展A，B，C和D範圍，以及Unicode 7.0的貨幣符號區塊中的所有字形。

3.8.14。多視窗

裝置實作可以選擇不實作任何多視窗模式，但是如果它具有相同時間顯示多個活動的能力，則必須根據應用程式的應用程式行為和API實作此類多視窗模式。 Android SDK多視窗模式支援文件並滿足以下要求：

  • 應用程式可以指示它們是否能夠在AndoidManifest.xml檔案中以多視窗模式運行，要么透過android:resizeableActivity屬性明確或隱式屬性或隱式targetsdkversion> 24.不以多視窗模式啟動。可以在多視窗模式下啟動未設定其清單檔案（targetsdkversion <24）中屬性的應用程序，但是該系統必須警告該應用程式在多視窗模式下可能無法按預期工作。
  • 如果螢幕高度和寬度均小於440 dp，則裝置實作不得提供分割畫面或自由形式模式。
  • 具有螢幕尺寸xlarge裝置實作應支援自由形式模式。
  • Android電視設備的實作必須支援圖片中的圖片（PIP）模式多窗口，並在PIP開啟時將PIP多窗口放在右上角。
  • 具有PIP模式多視窗支援的設備實作必須為PIP視窗分配至少240x135 dp。
  • 如果支援PIP多窗模式，則必須使用KeyEvent.KEYCODE_WINDOW鍵來控制PIP視窗。否則，鑰匙必須可用於前景活動。

3.9.設備管理

Android包含允許安全感知應用程式在系統層級執行裝置管理功能的功能，例如透過Android裝置管理API執行密碼原則或執行遠端清除]。設備實作必須提供DevicePolicyManager類別的實作。支援安全鎖定畫面的裝置實作必須實作Android SDK文件中定義的全部裝置管理策略，並報告平台功能Android.software.device.device_admin。

3.9.1設備配置

3.9.1.1設備所有者提供

如果裝置實作聲明android.software.device_admin功能，則必須實作裝置策略用戶端（DPC）應用程式的裝置擁有者應用程式的配置，如下所示：

設備實現可能具有預先設定的執行設備管理功能的應用程式應用程序，但是如果未經用戶或設備的管理員的明確同意或操作，則不能將此應用程式設定為設備所有者應用程式。

3.9.1.2託管個人資料供應

如果裝置實作將android.software.managed_users聲明，則必須有可能將裝置原則控制器（DPC）應用程式註冊為新的託管設定檔的擁有者。

託管設定檔設定流程（由Android.app.action.provision_managed_profile啟動的流程）使用者體驗必須與AOSP實作保持一致。

設備實作必須在設定使用者介面中提供以下使用者負擔，以便在裝置策略控制器（DPC）停用特定係統功能時向使用者指示：

  • 一致的圖示或其他使用者負擔能力（例如上游AOSP資訊圖示）表示特定設定受設備管理限制時。
  • 由設備管理員透過setShortSupportMessage提供的簡短說明訊息。
  • DPC應用程式的圖示。

3.9.2託管個人資料支持

可託管的設定檔設備是那些設備：

託管設定檔的設備必須：

  • 聲明平台功能flag android.software.managed_users 。
  • 透過android.app.admin.DevicePolicyManager APIS支援託管設定檔。
  • 允許建立一個和只有一個託管的個人資料。
  • 使用圖標徽章（類似於AOSP上游工作徽章）來表示託管應用程序，小部件以及其他徽章UI元素，例如恢復和通知。
  • 顯示通知圖示（類似於AOSP上游工作徽章），以指示使用者何時在託管設定檔應用程式中。
  • 顯示敬酒，指示使用者在裝置醒來（action_user_present）時在託管設定檔中，並且前景應用程式在託管設定檔中。
  • 如果存在託管設定文件，請在意圖「選擇器」中顯示視覺負擔，以允許用戶將意圖從託管設定檔轉發給主要用戶，反之亦然，如果裝置策略控制器啟用。
  • 如果存在託管設定檔的地方，請揭露主要使用者和託管設定檔的以下使用者提供的負擔：
    • 針對主要用戶和託管設定檔的電池，位置，行動數據和儲存使用量單獨考慮。
    • 主用戶或託管設定檔中安裝的VPN應用程式的獨立管理。
    • 對主要使用者或託管設定檔中安裝的應用程式的獨立管理。
    • 在主要使用者或託管設定檔中的帳戶獨立管理。
  • 如果裝置策略控制器允許，請確保可以從託管設定檔（如果存在的話）（如果存在的話）（如果存在的話）搜尋並尋找呼叫者資訊的預裝，聯絡人和訊息應用程式可以搜尋並尋找呼叫者資訊。當託管設定檔的聯絡人顯示在預先安裝的呼叫日誌中，呼叫UI，過程中和錯失通知，聯絡人和訊息應用程式中，他們應該用與指示託管設定檔應用程式相同的徽章徽章。
  • 必須確保滿足適用於啟用多個使用者的裝置適用的所有安全要求（請參閱第9.5節），即使除了主要使用者之外，託管設定檔也不被視為另一個使用者。
  • 支援指定單獨的鎖定畫面滿足以下要求的能力，以授予對託管設定檔中執行的應用程式的存取權。

3.10.無障礙

Android提供了一個可訪問性層，可幫助殘疾用戶更輕鬆地導航其裝置。此外，Android還提供了平台API，使可訪問性服務實現能夠接收用於用戶和系統事件的回調，並產生替代的反饋機制，例如文字轉語音，觸覺反饋以及軌跡球/D-Pad導航。

設備實現包括以下要求：

  • Android Automotive實作應提供與預設Android實作一致的Android可訪問性框架的實作。
  • 設備實作（不包括Android汽車）必須提供與預設的Android實作一致的Android可訪問性框架的實作。
  • 設備實作（不包括Android汽車）必須支援透過Android.Ascorsibilityservice API的第三方可訪問性服務實作。
  • 設備實現（排除Android汽車）必須產生可訪問性，並以與預設的Android實現一致的方式將這些事件交付給所有註冊的可訪問性服務實現

  • 設備實作（Android Automotive和Android Watch設備，不包括音訊輸出），必須提供可啟用和停用可訪問性服務的使用者存取機制，並且必須對Android.provider.settings.action.action_accessibility_settings的意圖顯示此介面。

  • Android device implementations with audio output are STRONGLY RECOMMENDED to provide implementations of accessibility services on the device comparable in or exceeding functionality of the TalkBack** and Switch Access accessibility services (https://github.com/google/talkback).

  • Android Watch devices with audio output SHOULD provide implementations of an accessibility service on the device comparable in or exceeding functionality of the TalkBack accessibility service (https://github.com/google/talkback).
  • Device implementations SHOULD provide a mechanism in the out-of-box setup flow for users to enable relevant accessibility services, as well as options to adjust the font size, display size and magnification gestures.

** For languages supported by Text-to-speech.

Also, note that if there is a preloaded accessibility service, it MUST be a Direct Boot aware {directBootAware} app if the device has encrypted storage using File Based Encryption (FBE).

3.11.文字轉語音

Android includes APIs that allow applications to make use of text-to-speech (TTS) services and allows service providers to provide implementations of TTS services. Device implementations reporting the feature android.hardware.audio.output MUST meet these requirements related to the Android TTS framework .

Android Automotive implementations:

  • MUST support the Android TTS framework APIs.
  • MAY support installation of third-party TTS engines. If supported, partners MUST provide a user-accessible interface that allows the user to select a TTS engine for use at system level.

All other device implementations:

  • MUST support the Android TTS framework APIs and SHOULD include a TTS engine supporting the languages available on the device. Note that the upstream Android open source software includes a full-featured TTS engine implementation.
  • MUST support installation of third-party TTS engines.
  • MUST provide a user-accessible interface that allows users to select a TTS engine for use at the system level.

3.12. TV Input Framework

The Android Television Input Framework (TIF) simplifies the delivery of live content to Android Television devices. TIF provides a standard API to create input modules that control Android Television devices. Android Television device implementations MUST support TV Input Framework.

Device implementations that support TIF MUST declare the platform feature android.software.live_tv.

3.12.1. TV App

Any device implementation that declares support for Live TV MUST have an installed TV application (TV App). The Android Open Source Project provides an implementation of the TV App.

The TV App MUST provide facilities to install and use TV Channels and meet the following requirements:

  • Device implementations MUST allow third-party TIF-based inputs ( third-party inputs ) to be installed and managed.
  • Device implementations MAY provide visual separation between pre-installed TIF-based inputs (installed inputs) and third-party inputs.
  • Device implementations MUST NOT display the third-party inputs more than a single navigation action away from the TV App (ie expanding a list of third-party inputs from the TV App).

3.12.1.1. Electronic Program Guide

Android Television device implementations MUST show an informational and interactive overlay, which MUST include an electronic program guide (EPG) generated from the values in the TvContract.Programs fields. The EPG MUST meet the following requirements:

  • The EPG MUST display information from all installed inputs and third-party inputs.
  • The EPG MAY provide visual separation between the installed inputs and third-party inputs.
  • The EPG is STRONGLY RECOMMENDED to display installed inputs and third-party inputs with equal prominence. The EPG MUST NOT display the third-party inputs more than a single navigation action away from the installed inputs on the EPG.
  • On channel change, device implementations MUST display EPG data for the currently playing program.

3.12.1.2.導航

The TV App MUST allow navigation for the following functions via the D-pad, Back, and Home keys on the Android Television device's input device(s) (ie remote control, remote control application, or game controller):

  • Changing TV channels
  • Opening EPG
  • Configuring and tuning to third-party TIF-based inputs
  • Opening Settings menu

The TV App SHOULD pass key events to HDMI inputs through CEC.

3.12.1.3. TV input app linking

Android Television device implementations MUST support TV input app linking , which allows all inputs to provide activity links from the current activity to another activity (ie a link from live programming to related content). The TV App MUST show TV input app linking when it is provided.

3.12.1.4. Time shifting

Android Television device implementations MUST support time shifting, which allows the user to pause and resume live content. Device implementations MUST provide the user a way to pause and resume the currently playing program, if time shifting for that program is available .

3.12.1.5. TV recording

Android Television device implementations are STRONGLY RECOMMENDED to support TV recording. If the TV input supports recording, the EPG MAY provide a way to record a program if the recording of such a program is not prohibited . Device implementations SHOULD provide a user interface to play recorded programs.

3.13.快速設定

Android device implementations SHOULD include a Quick Settings UI component that allow quick access to frequently used or urgently needed actions.

Android includes the quicksettings API allowing third party apps to implement tiles that can be added by the user alongside the system-provided tiles in the Quick Settings UI component. If a device implementation has a Quick Settings UI component, it:

  • MUST allow the user to add or remove tiles from a third-party app to Quick Settings.
  • MUST NOT automatically add a tile from a third-party app directly to Quick Settings.
  • MUST display all the user-added tiles from third-party apps alongside the system-provided quick setting tiles.

3.14。 Vehicle UI APIs

3.14.1. Vehicle Media UI

Any device implementation that declares automotive support MUST include a UI framework to support third-party apps consuming the MediaBrowser and MediaSession APIs.

The UI framework supporting third-party apps that depend on MediaBrowser and MediaSession has the following visual requirements:

  • MUST display MediaItem icons and notification icons unaltered.
  • MUST display those items as described by MediaSession, eg, metadata, icons, imagery.
  • MUST show app title.
  • MUST have drawer to present MediaBrowser hierarchy.

4. Application Packaging Compatibility

Device implementations MUST install and run Android “.apk” files as generated by the “aapt” tool included in the official Android SDK . For this reason device implementations SHOULD use the reference implementation's package management system.

The package manager MUST support verifying “.apk” files using the APK Signature Scheme v2 and JAR signing .

Devices implementations MUST NOT extend either the .apk , Android Manifest , Dalvik bytecode , or RenderScript bytecode formats in such a way that would prevent those files from installing and running correctly on other compatible devices.

Device implementations MUST NOT allow apps other than the current "installer of record" for the package to silently uninstall the app without any prompt, as documented in the SDK for the DELETE_PACKAGE permission. The only exceptions are the system package verifier app handling PACKAGE_NEEDS_VERIFICATION intent and the storage manager app handling ACTION_MANAGE_STORAGE intent.

5. Multimedia Compatibility

5.1. Media Codecs

Device implementations—

  • MUST support the core media formats specified in the Android SDK documentation, except where explicitly permitted in this document.

  • MUST support the media formats, encoders, decoders, file types, and container formats defined in the tables below and reported via MediaCodecList .

  • MUST also be able to decode all profiles reported in its CamcorderProfile

  • MUST be able to decode all formats it can encode. This includes all bitstreams that its encoders generate.

Codecs SHOULD aim for minimum codec latency, in other words, codecs—

  • SHOULD NOT consume and store input buffers and return input buffers only once processed
  • SHOULD NOT hold onto decoded buffers for longer than as specified by the standard (eg SPS).
  • SHOULD NOT hold onto encoded buffers longer than required by the GOP structure.

All of the codecs listed in the table below are provided as software implementations in the preferred Android implementation from the Android Open Source Project.

Please note that neither Google nor the Open Handset Alliance make any representation that these codecs are free from third-party patents. Those intending to use this source code in hardware or software products are advised that implementations of this code, including in open source software or shareware, may require patent licenses from the relevant patent holders.

5.1.1.音訊編解碼器

Format/Codec編碼器解碼器細節Supported File Types/Container Formats
MPEG-4 AAC Profile
(AAC LC)		 REQUIRED 1必需的Support for mono/stereo/5.0/5.1 2 content with standard sampling rates from 8 to 48 kHz.
  • 3GPP (.3gp)
  • MPEG-4 (.mp4, .m4a)
  • ADTS raw AAC (.aac, decode in Android 3.1+, encode in Android 4.0+, ADIF not supported)
  • MPEG-TS (.ts, not seekable, Android 3.0+)
MPEG-4 HE AAC Profile (AAC+) REQUIRED 1
(Android 4.1+)		必需的Support for mono/stereo/5.0/5.1 2 content with standard sampling rates from 16 to 48 kHz.
MPEG-4 HE AACv2
Profile (enhanced AAC+)		必需的Support for mono/stereo/5.0/5.1 2 content with standard sampling rates from 16 to 48 kHz.
AAC ELD (enhanced low delay AAC) REQUIRED 1
(Android 4.1+)		必需的
(Android 4.1+)		 Support for mono/stereo content with standard sampling rates from 16 to 48 kHz.
AMR-NB REQUIRED 3 REQUIRED 3 4.75 to 12.2 kbps sampled @ 8 kHz 3GPP (.3gp)
AMR-WB REQUIRED 3 REQUIRED 3 9 rates from 6.60 kbit/s to 23.85 kbit/s sampled @ 16 kHz
FLAC必需的
(Android 3.1+)		 Mono/Stereo (no multichannel). Sample rates up to 48 kHz (but up to 44.1 kHz is RECOMMENDED on devices with 44.1 kHz output, as the 48 to 44.1 kHz downsampler does not include a low-pass filter). 16-bit RECOMMENDED; no dither applied for 24-bit. FLAC (.flac) only
MP3必需的Mono/Stereo 8-320Kbps constant (CBR) or variable bitrate (VBR) MP3 (.mp3)
MIDI必需的MIDI Type 0 and 1. DLS Version 1 and 2. XMF and Mobile XMF. Support for ringtone formats RTTTL/RTX, OTA, and iMelody
  • Type 0 and 1 (.mid, .xmf, .mxmf)
  • RTTTL/RTX (.rtttl, .rtx)
  • OTA (.ota)
  • iMelody (.imy)
Vorbis必需的
  • Ogg (.ogg)
  • Matroska (.mkv, Android 4.0+)
PCM/WAVE REQUIRED 4
(Android 4.1+)		必需的16-bit linear PCM (rates up to limit of hardware). Devices MUST support sampling rates for raw PCM recording at 8000, 11025, 16000, and 44100 Hz frequencies. WAVE (.wav)
作品必需的
(Android 5.0+)		 Matroska (.mkv), Ogg(.ogg)

1 Required for device implementations that define android.hardware.microphone but optional for Android Watch device implementations.

2 Recording or playback MAY be performed in mono or stereo, but the decoding of AAC input buffers of multichannel streams (ie more than two channels) to PCM through the default AAC audio decoder in the and two channels) to PCM through the default AAC audio decoder in the and two channels) to PCM through the default AAC audio decoder in the and roid.支持的：

  • decoding is performed without downmixing (eg a 5.0 AAC stream must be decoded to five channels of PCM, a 5.1 AAC stream must be decoded to six channels of PCM),
  • dynamic range metadata, as defined in "Dynamic Range Control (DRC)" in ISO/IEC 14496-3, and the android.media.MediaFormat DRC keys to configure the dynamic range-related behaviors of the audio decoder. The AAC DRC keys were introduced in API 21,and are: KEY_AAC_DRC_ATTENUATION_FACTOR, KEY_AAC_DRC_BOOST_FACTOR, KEY_AAC_DRC_HEAVY_COMPRESSION, KEY_AAC_DRC_TARGET_REFERENCE_LEVEL and KEY_AAC_ENCODED_TARGET_LEVEL

3 Required for Android Handheld device implementations.

4 Required for device implementations that define android.hardware.microphone, including Android Watch device implementations.

5.1.2. Image Codecs

Format/Codec編碼器解碼器細節Supported File Types/Container Formats
JPEG必需的必需的Base+progressive JPEG (.jpg)
動圖必需的GIF (.gif)
巴布亞紐幾內亞必需的必需的PNG (.png)
BMP必需的BMP (.bmp)
網路P必需的必需的WebP (.webp)
生的必需的ARW (.arw), CR2 (.cr2), DNG (.dng), NEF (.nef), NRW (.nrw), ORF (.orf), PEF (.pef), RAF (.raf), RW2 (.rw2), SRW (.srw)

5.1.3.視訊編解碼器

  • Codecs advertising HDR profile support MUST support HDR static metadata parsing and handling.

  • If a media codec advertises intra refresh support, then it MUST support the refresh periods in the range of 10 - 60 frames and accurately operate within 20% of configured refresh period.

  • Video codecs MUST support output and input bytebuffer sizes that accommodate the largest feasible compressed and uncompressed frame as dictated by the standard and configuration but also not overallocate.

  • Video encoders and decoders MUST support YUV420 flexible color format (COLOR_FormatYUV420Flexible).

Format/Codec編碼器解碼器細節Supported File Types/
Container Formats
H.263可能可能
  • 3GPP (.3gp)
  • MPEG-4 (.mp4)
H.264 AVC REQUIRED 2 REQUIRED 2 See section 5.2 and 5.3 for details
  • 3GPP (.3gp)
  • MPEG-4 (.mp4)
  • MPEG-2 TS (.ts, AAC audio only, not seekable, Android 3.0+)
H.265 HEVC REQUIRED 5 See section 5.3 for details MPEG-4 (.mp4)
MPEG-2 STRONGLY RECOMMENDED 6 Main Profile MPEG2-TS
MPEG-4 SP REQUIRED 2 3GPP (.3gp)
VP8 3 REQUIRED 2
(Android 4.3+)		 REQUIRED 2
(Android 2.3.3+)		 See section 5.2 and 5.3 for details
VP9 REQUIRED 2
(Android 4.4+)		 See section 5.3 for details

1 Required for device implementations that include camera hardware and define android.hardware.camera or android.hardware.camera.front.

2 Required for device implementations except Android Watch devices.

3 For acceptable quality of web video streaming and video-conference services, device implementations SHOULD use a hardware VP8 codec that meets the requirements .

4 Device implementations SHOULD support writing Matroska WebM files.

5 STRONGLY RECOMMENDED for Android Automotive, optional for Android Watch, and required for all other device types.

6 Applies only to Android Television device implementations.

5.2.視訊編碼

Video codecs are optional for Android Watch device implementations.

H.264, VP8, VP9 and HEVC video encoders—

  • MUST support dynamically configurable bitrates.
  • SHOULD support variable frame rates, where video encoder SHOULD determine instantaneous frame duration based on the timestamps of input buffers, and allocate its bit bucket based on that frame duration.

H.263 and MPEG-4 video encoder SHOULD support dynamically configurable bitrates.

All video encoders SHOULD meet the following bitrate targets over two sliding windows:

  • It SHOULD be not more than ~15% over the bitrate between intraframe (I-frame) intervals.
  • It SHOULD be not more than ~100% over the bitrate over a sliding window of 1 second.

5.2.1. H.263

Android device implementations with H.263 encoders MUST support Baseline Profile Level 45.

5.2.2. H-264

Android device implementations with H.264 codec support:

  • MUST support Baseline Profile Level 3.
    However, support for ASO (Arbitrary Slice Ordering), FMO (Flexible Macroblock Ordering) and RS (Redundant Slices) is OPTIONAL. Moreover, to maintain compatibility with other Android devices, it is RECOMMENDED that ASO, FMO and RS are not used for Baseline Profile by encoders.
  • MUST support the SD (Standard Definition) video encoding profiles in the following table.
  • SHOULD support Main Profile Level 4.
  • SHOULD support the HD (High Definition) video encoding profiles as indicated in the following table.
  • In addition, Android Television devices are STRONGLY RECOMMENDED to encode HD 1080p video at 30 fps.
SD (Low quality) SD (High quality) HD 720p 1 HD 1080p 1
視訊解析度320 x 240 px 720 x 480 px 1280 x 720 px 1920 x 1080 像素
Video frame rate 20 fps 30 幀/秒30 幀/秒30 幀/秒
視訊比特率384 Kbps 2 Mbps 4 Mbps 10Mbps

1 When supported by hardware, but STRONGLY RECOMMENDED for Android Television devices.

5.2.3. VP8

Android device implementations with VP8 codec support MUST support the SD video encoding profiles and SHOULD support the following HD (High Definition) video encoding profiles.

SD (Low quality) SD (High quality) HD 720p 1 HD 1080p 1
視訊解析度320 x 180 px 640 x 360 px 1280 x 720 px 1920 x 1080 像素
Video frame rate 30 幀/秒30 幀/秒30 幀/秒30 幀/秒
視訊比特率800 Kbps 2 Mbps 4 Mbps 10Mbps

1 When supported by hardware.

5.3.視訊解碼

Video codecs are optional for Android Watch device implementations.

Device implementations—

  • MUST support dynamic video resolution and frame rate switching through the standard Android APIs within the same stream for all VP8, VP9, H.264, and H.265 codecs in real time and up to the maximum resolution supported by each codec on the device.

  • Implementations that support the Dolby Vision decoder—

  • MUST provide a Dolby Vision-capable extractor.

  • MUST properly display Dolby Vision content on the device screen or on a standard video output port (eg, HDMI).

  • Implementations that provide a Dolby Vision-capable extractor MUST set the track index of backward-compatible base-layer(s) (if present) to be the same as the combined Dolby Vision layer's track index.

5.3.1. MPEG-2

Android device implementations with MPEG-2 decoders must support the Main Profile High Level.

5.3.2. H.263

Android device implementations with H.263 decoders MUST support Baseline Profile Level 30 and Level 45.

5.3.3. MPEG-4

Android device implementations with MPEG-4 decoders MUST support Simple Profile Level 3.

5.3.4. H.264

Android device implementations with H.264 decoders:

  • MUST support Main Profile Level 3.1 and Baseline Profile.
    Support for ASO (Arbitrary Slice Ordering), FMO (Flexible Macroblock Ordering) and RS (Redundant Slices) is OPTIONAL.
  • MUST be capable of decoding videos with the SD (Standard Definition) profiles listed in the following table and encoded with the Baseline Profile and Main Profile Level 3.1 (including 720p30).
  • SHOULD be capable of decoding videos with the HD (High Definition) profiles as indicated in the following table.
  • In addition, Android Television devices—
    • MUST support High Profile Level 4.2 and the HD 1080p60 decoding profile.
    • MUST be capable of decoding videos with both HD profiles as indicated in the following table and encoded with either the Baseline Profile, Main Profile, or the High Profile Level 4.2
SD (Low quality) SD (High quality) HD 720p 1 HD 1080p 1
視訊解析度320 x 240 px 720 x 480 px 1280 x 720 px 1920 x 1080 像素
Video frame rate 30 幀/秒30 幀/秒60 幀/秒30 fps (60 fps 2 )
視訊比特率800 Kbps 2 Mbps 8 Mbps 20 Mbps

1 REQUIRED for when the height as reported by the Display.getSupportedModes() method is equal or greater than the video resolution.

2 REQUIRED for Android Television device implementations.

5.3.5。 H.265 (HEVC)

Android device implementations, when supporting H.265 codec as described in section 5.1.3 :

  • MUST support the Main Profile Level 3 Main tier and the SD video decoding profiles as indicated in the following table.
  • SHOULD support the HD decoding profiles as indicated in the following table.
  • MUST support the HD decoding profiles as indicated in the following table if there is a hardware decoder.
  • In addition, Android Television devices:
  • MUST support the HD 720p decoding profile.
  • STRONGLY RECOMMENDED to support the HD 1080p decoding profile. If the HD 1080p decoding profile is supported, it MUST support the Main Profile Level 4.1 Main tier.
  • SHOULD support the UHD decoding profile. If the UHD decoding profile is supported the codec MUST support Main10 Level 5 Main Tier profile.
SD (Low quality) SD (High quality)高清720p高清1080p超高畫質
視訊解析度352 x 288 px 720 x 480 px 1280 x 720 px 1920 x 1080 像素3840 x 2160 像素
Video frame rate 30 幀/秒30 幀/秒30 幀/秒30 fps (60 fps 1 ) 60 幀/秒
視訊比特率600 Kbps 1.6 Mbps 4 Mbps 5 Mbps 20 Mbps

1 REQUIRED for Android Television device implementations with H.265 hardware decoding.

5.3.6。 VP8

Android device implementations, when supporting VP8 codec as described in section 5.1.3 :

  • MUST support the SD decoding profiles in the following table.
  • SHOULD support the HD decoding profiles in the following table.
  • Android Television devices MUST support the HD 1080p60 decoding profile.
SD (Low quality) SD (High quality) HD 720p 1 HD 1080p 1
視訊解析度320 x 180 px 640 x 360 px 1280 x 720 px 1920 x 1080 像素
Video frame rate 30 幀/秒30 幀/秒30 fps (60 fps 2 ) 30 (60 fps 2 )
視訊比特率800 Kbps 2 Mbps 8 Mbps 20 Mbps

1 REQUIRED for when the height as reported by the Display.getSupportedModes() method is equal or greater than the video resolution.

2 REQUIRED for Android Television device implementations.

5.3.7. VP9

Android device implementations, when supporting VP9 codec as described in section 5.1.3 :

  • MUST support the SD video decoding profiles as indicated in the following table.
  • SHOULD support the HD decoding profiles as indicated in the following table.
  • MUST support the HD decoding profiles as indicated in the following table, if there is a hardware decoder.

  • In addition, Android Television devices:

    • MUST support the HD 720p decoding profile.
    • STRONGLY RECOMMENDED to support the HD 1080p decoding profile.
    • SHOULD support the UHD decoding profile. If the UHD video decoding profile is supported, it MUST support 8-bit color depth and SHOULD support VP9 Profile 2 (10-bit).
SD (Low quality) SD (High quality)高清720p高清1080p超高畫質
視訊解析度320 x 180 px 640 x 360 px 1280 x 720 px 1920 x 1080 像素3840 x 2160 像素
Video frame rate 30 幀/秒30 幀/秒30 幀/秒30 fps (60 fps 1 ) 60 幀/秒
視訊比特率600 Kbps 1.6 Mbps 4 Mbps 5 Mbps 20 Mbps

1 REQUIRED for Android Television device implementations with VP9 hardware decoding.

5.4.聲音錄製

While some of the requirements outlined in this section are stated as SHOULD since Android 4.3, the Compatibility Definition for a future version is planned to change these to MUST. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements that are stated as SHOULD, or they will not be able to attain Android compatibility when upgraded to the future version.

5.4.1. Raw Audio Capture

Device implementations that declare android.hardware.microphone MUST allow capture of raw audio content with the following characteristics:

  • Format : Linear PCM, 16-bit
  • Sampling rates : 8000, 11025, 16000, 44100
  • Channels : Mono

The capture for the above sample rates MUST be done without up-sampling, and any down-sampling MUST include an appropriate anti-aliasing filter.

Device implementations that declare android.hardware.microphone SHOULD allow capture of raw audio content with the following characteristics:

  • Format : Linear PCM, 16-bit
  • Sampling rates : 22050, 48000
  • Channels : Stereo

If capture for the above sample rates is supported, then the capture MUST be done without up-sampling at any ratio higher than 16000:22050 or 44100:48000. Any up-sampling or down-sampling MUST include an appropriate anti-aliasing filter.

5.4.2. Capture for Voice Recognition

The android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION audio source MUST support capture at one of the sampling rates, 44100 and 48000.

In addition to the above recording specifications, when an application has started recording an audio stream using the android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION audio source:

  • The device SHOULD exhibit approximately flat amplitude versus frequency characteristics: specifically, ±3 dB, from 100 Hz to 4000 Hz.
  • Audio input sensitivity SHOULD be set such that a 90 dB sound power level (SPL) source at 1000 Hz yields RMS of 2500 for 16-bit samples.
  • PCM amplitude levels SHOULD linearly track input SPL changes over at least a 30 dB range from -18 dB to +12 dB re 90 dB SPL at the microphone.
  • Total harmonic distortion SHOULD be less than 1% for 1 kHz at 90 dB SPL input level at the microphone.
  • Noise reduction processing, if present, MUST be disabled.
  • Automatic gain control, if present, MUST be disabled.

If the platform supports noise suppression technologies tuned for speech recognition, the effect MUST be controllable from the android.media.audiofx.NoiseSuppressor API. Moreover, the UUID field for the noise suppressor's effect descriptor MUST uniquely identify each implementation of the noise suppression technology.

5.4.3. Capture for Rerouting of Playback

The android.media.MediaRecorder.AudioSource class includes the REMOTE_SUBMIX audio source. Devices that declare android.hardware.audio.output MUST properly implement the REMOTE_SUBMIX audio source so that when an application uses the android.media.AudioRecord API to record from this audio source, it can capture awing mix 科：

  • STREAM_RING
  • STREAM_ALARM
  • STREAM_NOTIFICATION

5.5.音訊播放

Device implementations that declare android.hardware.audio.output MUST conform to the requirements in this section.

5.5.1. Raw Audio Playback

The device MUST allow playback of raw audio content with the following characteristics:

  • Format : Linear PCM, 16-bit
  • Sampling rates : 8000, 11025, 16000, 22050, 32000, 44100
  • Channels : Mono, Stereo

The device SHOULD allow playback of raw audio content with the following characteristics:

  • Sampling rates : 24000, 48000

5.5.2.音訊效果

Android provides an API for audio effects for device implementations. Device implementations that declare the feature android.hardware.audio.output:

  • MUST support the EFFECT_TYPE_EQUALIZER and EFFECT_TYPE_LOUDNESS_ENHANCER implementations controllable through the AudioEffect subclasses Equalizer, LoudnessEnhancer.
  • MUST support the visualizer API implementation, controllable through the Visualizer class.
  • SHOULD support the EFFECT_TYPE_BASS_BOOST, EFFECT_TYPE_ENV_REVERB, EFFECT_TYPE_PRESET_REVERB, and EFFECT_TYPE_VIRTUALIZER implementations controllable through the AudioEffect sub-classes BassBoost, EnvironmentalReverb, PresetReverb, and Virtualizer.

5.5.3. Audio Output Volume

Android Television device implementations MUST include support for system Master Volume and digital audio output volume attenuation on supported outputs, except for compressed audio passthrough output (where no audio decoding is done on the device).

Android Automotive device implementations SHOULD allow adjusting audio volume separately per each audio stream using the content type or usage as defined by AudioAttributes and car audio usage as publicly defined in android.car.CarAudioManager .

5.6. Audio Latency

Audio latency is the time delay as an audio signal passes through a system. Many classes of applications rely on short latencies, to achieve real-time sound effects.

For the purposes of this section, use the following definitions:

  • output latency . The interval between when an application writes a frame of PCM-coded data and when the corresponding sound is presented to environment at an on-device transducer or signal leaves the device via a port and can be observed externally.
  • cold output latency . The output latency for the first frame, when the audio output system has been idle and powered down prior to the request.
  • continuous output latency . The output latency for subsequent frames, after the device is playing audio.
  • input latency . The interval between when a sound is presented by environment to device at an on-device transducer or signal enters the device via a port and when an application reads the corresponding frame of PCM-coded data.
  • lost input . The initial portion of an input signal that is unusable or unavailable.
  • cold input latency . The sum of lost input time and the input latency for the first frame, when the audio input system has been idle and powered down prior to the request.
  • continuous input latency . The input latency for subsequent frames, while the device is capturing audio.
  • cold output jitter . The variability among separate measurements of cold output latency values.
  • cold input jitter . The variability among separate measurements of cold input latency values.
  • continuous round-trip latency . The sum of continuous input latency plus continuous output latency plus one buffer period. The buffer period allows time for the app to process the signal and time for the app to mitigate phase difference between input and output streams.
  • OpenSL ES PCM buffer queue API . The set of PCM-related OpenSL ES APIs within Android NDK .

Device implementations that declare android.hardware.audio.output are STRONGLY RECOMMENDED to meet or exceed these audio output requirements:

  • cold output latency of 100 milliseconds or less
  • continuous output latency of 45 milliseconds or less
  • minimize the cold output jitter

If a device implementation meets the requirements of this section after any initial calibration when using the OpenSL ES PCM buffer queue API, for continuous output latency and cold output latency over at least one supported audio output device, it is STRONGLY RECOMMENDED to report support for low-latency audio, by reporting the feature android.hardware.audio.low_latency via the android.content.pm.PackageManager class. Conversely, if the device implementation does not meet these requirements it MUST NOT report support for low-latency audio.

Device implementations that include android.hardware.microphone are STRONGLY RECOMMENDED to meet these input audio requirements:

  • cold input latency of 100 milliseconds or less
  • continuous input latency of 30 milliseconds or less
  • continuous round-trip latency of 50 milliseconds or less
  • minimize the cold input jitter

5.7.網路協定

Devices MUST support the media network protocols for audio and video playback as specified in the Android SDK documentation. Specifically, devices MUST support the following media network protocols:

Segment formats參考） Required codec support
MPEG-2 Transport Stream ISO 13818 Video codecs:
  • H264 AVC
  • MPEG-4 SP
  • MPEG-2
See section 5.1.3 for details on H264 AVC, MPEG2-4 SP,
and MPEG-2.

Audio codecs:

  • 亞克力
See section 5.1.1 for details on AAC and its variants.
AAC with ADTS framing and ID3 tags ISO 13818-7 See section 5.1.1 for details on AAC and its variants
網路VTT網路VTT

  • RTSP (RTP, SDP)

    The following RTP audio video profile and related codecs MUST be supported. For exceptions please see the table footnotes in section 5.1 .

個人資料名稱參考） Required codec support
H264 AVC RFC 6184 See section 5.1.3 for details on H264 AVC
MP4A-LATM RFC 6416 See section 5.1.1 for details on AAC and its variants
H263-1998 RFC 3551
RFC 4629
RFC 2190		 See section 5.1.3 for details on H263
H263-2000 RFC 4629 See section 5.1.3 for details on H263
抗微生物藥物抗藥性RFC 4867 See section 5.1.1 for details on AMR-NB
AMR-WB RFC 4867 See section 5.1.1 for details on AMR-WB
MP4V-ES RFC 6416 See section 5.1.3 for details on MPEG-4 SP
mpeg4-generic RFC 3640 See section 5.1.1 for details on AAC and its variants
MP2T RFC 2250 See MPEG-2 Transport Stream underneath HTTP Live Streaming for details

5.8. Secure Media

Device implementations that support secure video output and are capable of supporting secure surfaces MUST declare support for Display.FLAG_SECURE. Device implementations that declare support for Display.FLAG_SECURE, if they support a wireless display protocol, MUST secure the link with a cryptographically strong mechanism such as HDCP 2.x or higher for Miracast wireless displays. Similarly if they support a wired external display, the device implementations MUST support HDCP 1.2 or higher. Android Television device implementations MUST support HDCP 2.2 for devices supporting 4K resolution and HDCP 1.4 or above for lower resolutions. The upstream Android open source implementation includes support for wireless (Miracast) and wired (HDMI) displays that satisfies this requirement.

5.9. Musical Instrument Digital Interface (MIDI)

If a device implementation supports the inter-app MIDI software transport (virtual MIDI devices), and it supports MIDI over all of the following MIDI-capable hardware transports for which it provides generic non-MIDI connectivity, it is STRONGLY RECOMMENDED to report support for feature android.software.midi via the android.content.pm.PackageManager class.

The MIDI-capable hardware transports are:

  • USB host mode (section 7.7 USB)
  • USB peripheral mode (section 7.7 USB)
  • MIDI over Bluetooth LE acting in central role (section 7.4.3 Bluetooth)

Conversely, if the device implementation provides generic non-MIDI connectivity over a particular MIDI-capable hardware transport listed above, but does not support MIDI over that hardware transport, it MUST NOT report support for feature android.software.midi.

5.10.專業音響

If a device implementation meets all of the following requirements, it is STRONGLY RECOMMENDED to report support for feature android.hardware.audio.pro via the android.content.pm.PackageManager class.

  • The device implementation MUST report support for feature android.hardware.audio.low_latency.
  • The continuous round-trip audio latency, as defined in section 5.6 Audio Latency, MUST be 20 milliseconds or less and SHOULD be 10 milliseconds or less over at least one supported path.
  • If the device includes a 4 conductor 3.5mm audio jack, the continuous round-trip audio latency MUST be 20 milliseconds or less over the audio jack path, and SHOULD be 10 milliseconds or less over at the audio jack path.
  • The device implementation MUST include a USB port(s) supporting USB host mode and USB peripheral mode.
  • The USB host mode MUST implement the USB audio class.
  • If the device includes an HDMI port, the device implementation MUST support output in stereo and eight channels at 20-bit or 24-bit depth and 192 kHz without bit-depth loss or resampling.
  • The device implementation MUST report support for feature android.software.midi.
  • If the device includes a 4 conductor 3.5mm audio jack, the device implementation is STRONGLY RECOMMENDED to comply with section Mobile device (jack) specifications of the Wired Audio Headset Specification (v1.1) .

Latencies and USB audio requirements MUST be met using the OpenSL ES PCM buffer queue API.

In addition, a device implementation that reports support for this feature SHOULD:

  • Provide a sustainable level of CPU performance while audio is active.
  • Minimize audio clock inaccuracy and drift relative to standard time.
  • Minimize audio clock drift relative to the CPU CLOCK_MONOTONIC when both are active.
  • Minimize audio latency over on-device transducers.
  • Minimize audio latency over USB digital audio.
  • Document audio latency measurements over all paths.
  • Minimize jitter in audio buffer completion callback entry times, as this affects usable percentage of full CPU bandwidth by the callback.
  • Provide zero audio underruns (output) or overruns (input) under normal use at reported latency.
  • Provide zero inter-channel latency difference.
  • Minimize MIDI mean latency over all transports.
  • Minimize MIDI latency variability under load (jitter) over all transports.
  • Provide accurate MIDI timestamps over all transports.
  • Minimize audio signal noise over on-device transducers, including the period immediately after cold start.
  • Provide zero audio clock difference between the input and output sides of corresponding end-points, when both are active. Examples of corresponding end-points include the on-device microphone and speaker, or the audio jack input and output.
  • Handle audio buffer completion callbacks for the input and output sides of corresponding end-points on the same thread when both are active, and enter the output callback immediately after the return from the input callback. Or if it is not feasible to handle the callbacks on the same thread, then enter the output callback shortly after entering the input callback to permit the application to have a consistent timing of the input and output sides.
  • Minimize the phase difference between HAL audio buffering for the input and output sides of corresponding end-points.
  • Minimize touch latency.
  • Minimize touch latency variability under load (jitter).

5.11. Capture for Unprocessed

Starting from Android 7.0, a new recording source has been added. It can be accessed using the android.media.MediaRecorder.AudioSource.UNPROCESSED audio source. In OpenSL ES, it can be accessed with the record preset SL_ANDROID_RECORDING_PRESET_UNPROCESSED .

A device MUST satisfy all of the following requirements to report support of the unprocessed audio source via the android.media.AudioManager property PROPERTY_SUPPORT_AUDIO_SOURCE_UNPROCESSED :

  • The device MUST exhibit approximately flat amplitude-versus-frequency characteristics in the mid-frequency range: specifically ±10dB from 100 Hz to 7000 Hz.

  • The device MUST exhibit amplitude levels in the low frequency range: specifically from ±20 dB from 5 Hz to 100 Hz compared to the mid-frequency range.

  • The device MUST exhibit amplitude levels in the high frequency range: specifically from ±30 dB from 7000 Hz to 22 KHz compared to the mid-frequency range.

  • Audio input sensitivity MUST be set such that a 1000 Hz sinusoidal tone source played at 94 dB Sound Pressure Level (SPL) yields a response with RMS of 520 for 16 bit-samples (or -36 dB Scale for floating Fullamples (or -36 dB Sc ）。

  • SNR > 60 dB (difference between 94 dB SPL and equivalent SPL of self noise, A-weighted).

  • Total harmonic distortion MUST be less than 1% for 1 kHZ at 90 dB SPL input level at the microphone.

  • The only signal processing allowed in the path is a level multiplier to bring the level to desired range. This level multiplier MUST NOT introduce delay or latency to the signal path.

  • No other signal processing is allowed in the path, such as Automatic Gain Control, High Pass Filter, or Echo Cancellation. If any signal processing is present in the architecture for any reason, it MUST be disabled and effectively introduce zero delay or extra latency to the signal path.

All SPL measurements are made directly next to the microphone under test.

For multiple microphone configurations, these requirements apply to each microphone.

It is STRONGLY RECOMMENDED that a device satisfy as many of the requirements for the signal path for the unprocessed recording source; however, a device must satisfy all of these requirements, listed above, if it claims to support the unprocessed audio source.

6. Developer Tools and Options Compatibility

6.1.開發者工具

Device implementations MUST support the Android Developer Tools provided in the Android SDK. Android compatible devices MUST be compatible with:

  • Android Debug Bridge (adb)
    • Device implementations MUST support all adb functions as documented in the Android SDK including dumpsys .
    • The device-side adb daemon MUST be inactive by default and there MUST be a user-accessible mechanism to turn on the Android Debug Bridge. If a device implementation omits USB peripheral mode, it MUST implement the Android Debug Bridge via local-area network (such as Ethernet or 802.11).
    • Android includes support for secure adb. Secure adb enables adb on known authenticated hosts. Device implementations MUST support secure adb.
  • Dalvik Debug Monitor Service (ddms)
    • Device implementations MUST support all ddms features as documented in the Android SDK.
    • As ddms uses adb, support for ddms SHOULD be inactive by default, but MUST be supported whenever the user has activated the Android Debug Bridge, as above.
  • Monkey Device implementations MUST include the Monkey framework, and make it available for applications to use.
  • SysTrace
    • Device implementations MUST support systrace tool as documented in the Android SDK. Systrace must be inactive by default, and there MUST be a user-accessible mechanism to turn on Systrace.
    • Most Linux-based systems and Apple Macintosh systems recognize Android devices using the standard Android SDK tools, without additional support; however Microsoft Windows systems typically require a driver for new Android devices. (For instance, new vendor IDs and sometimes new device IDs require custom USB drivers for Windows systems.)
    • If a device implementation is unrecognized by the adb tool as provided in the standard Android SDK, device implementers MUST provide Windows drivers allowing developers to connect to the device using the adb protocol. These drivers MUST be provided for Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 10 in both 32-bit and 64-bit versions.

6.2.開發者選項

Android includes support for developers to configure application development-related settings. Device implementations MUST honor the android.settings.APPLICATION_DEVELOPMENT_SETTINGS intent to show application development-related settings The upstream Android implementation hides the Developer Options menu by default and enables users to launch Developer Options after pressing seven (7) times on the Settings > About Device > Build Number menu item. Device implementations MUST provide a consistent experience for Developer Options. Specifically, device implementations MUST hide Developer Options by default and MUST provide a mechanism to enable Developer Options that is consistent with the upstream Android implementation.

Android Automotive implementations MAY limit access to the Developer Options menu by visually hiding or disabling the menu when the vehicle is in motion.

7. Hardware Compatibility

If a device includes a particular hardware component that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation. If an API in the SDK interacts with a hardware component that is stated to be optional and the device implementation does not possess that component:

  • Complete class definitions (as documented by the SDK) for the component APIs MUST still be presented.
  • The API's behaviors MUST be implemented as no-ops in some reasonable fashion.
  • API methods MUST return null values where permitted by the SDK documentation.
  • API methods MUST return no-op implementations of classes where null values are not permitted by the SDK documentation.
  • API methods MUST NOT throw exceptions not documented by the SDK documentation.

A typical example of a scenario where these requirements apply is the telephony API: Even on non-phone devices, these APIs must be implemented as reasonable no-ops.

Device implementations MUST consistently report accurate hardware configuration information via the getSystemAvailableFeatures() and hasSystemFeature(String) methods on the android.content.pm.PackageManager class for the same build fingerprint.

7.1.顯示和圖形

Android includes facilities that automatically adjust application assets and UI layouts appropriately for the device to ensure that third-party applications run well on a variety of hardware configurations . Devices MUST properly implement these APIs and behaviors, as detailed in this section.

The units referenced by the requirements in this section are defined as follows:

  • physical diagonal size . The distance in inches between two opposing corners of the illuminated portion of the display.
  • dots per inch (dpi) . The number of pixels encompassed by a linear horizontal or vertical span of 1”. Where dpi values are listed, both horizontal and vertical dpi must fall within the range.
  • aspect ratio . The ratio of the pixels of the longer dimension to the shorter dimension of the screen. For example, a display of 480x854 pixels would be 854/480 = 1.779, or roughly “16:9”.
  • density-independent pixel (dp) . The virtual pixel unit normalized to a 160 dpi screen, calculated as: pixels = dps * (density/160).

7.1.1. Screen Configuration

7.1.1.1.螢幕尺寸

Android Watch devices (detailed in section 2 ) MAY have smaller screen sizes as described in this section.

The Android UI framework supports a variety of different screen sizes, and allows applications to query the device screen size (aka “screen layout") via android.content.res.Configuration.screenLayout with the SCREENLAYOUT_SIZE_MASK. Device implementations MUST report the correct screen size as defined in the Android SDK documentation and determined by the upstream Android platform. Specifically, device implementations MUST report the correct screen size according to the following logical density-independent pixel (dp) screen dimensions.

  • Devices MUST have screen sizes of at least 426 dp x 320 dp ('small'), unless it is an Android Watch device.
  • Devices that report screen size 'normal' MUST have screen sizes of at least 480 dp x 320 dp.
  • Devices that report screen size 'large' MUST have screen sizes of at least 640 dp x 480 dp.
  • Devices that report screen size 'xlarge' MUST have screen sizes of at least 960 dp x 720 dp.

另外：

  • Android Watch devices MUST have a screen with the physical diagonal size in the range from 1.1 to 2.5 inches.
  • Android Automotive devices MUST have a screen with the physical diagonal size greater than or equal to 6 inches.
  • Android Automotive devices MUST have a screen size of at least 750 dp x 480 dp.
  • Other types of Android device implementations, with a physically integrated screen, MUST have a screen at least 2.5 inches in physical diagonal size.

Devices MUST NOT change their reported screen size at any time.

Applications optionally indicate which screen sizes they support via the <supports-screens> attribute in the AndroidManifest.xml file. Device implementations MUST correctly honor applications' stated support for small, normal, large, and xlarge screens, as described in the Android SDK documentation.

7.1.1.2. Screen Aspect Ratio

While there is no restriction to the screen aspect ratio value of the physical screen display, the screen aspect ratio of the surface that third-party apps are rendered on and which can be derived from the values reported via the DisplayMetrics MUST meet the following requirements:

  • If the uiMode is configured as UI_MODE_TYPE_WATCH, the aspect ratio value MAY be set as 1.0 (1:1).
  • If the third-party app indicates that it is resizeable via the android:resizeableActivity attribute, there are no restrictions to the aspect ratio value.
  • For all other cases, the aspect ratio MUST be a value between 1.3333 (4:3) and 1.86 (roughly 16:9) unless the app has indicated explicitly that it supports a higher screen aspect ratio through the maxAspectRatio metadata value.

7.1.1.3. Screen Density

The Android UI framework defines a set of standard logical densities to help application developers target application resources. By default, device implementations MUST report only one of the following logical Android framework densities through the DENSITY_DEVICE_STABLE API and this value MUST NOT change at any time; however, the device MAY report a different arbitrary density according to the display configuration changes made by the user (for example, display size) set after initial boot.

  • 120 dpi (ldpi)
  • 160 dpi (mdpi)
  • 213 dpi (tvdpi)
  • 240 dpi (hdpi)
  • 260 dpi (260dpi)
  • 280 dpi (280dpi)
  • 300 dpi (300dpi)
  • 320 dpi (xhdpi)
  • 340 dpi (340dpi)
  • 360 dpi (360dpi)
  • 400 dpi (400dpi)
  • 420 dpi (420dpi)
  • 480 dpi (xxhdpi)
  • 560 dpi (560dpi)
  • 640 dpi (xxxhdpi)

Device implementations SHOULD define the standard Android framework density that is numerically closest to the physical density of the screen, unless that logical density pushes the reported screen size below the minimum supported. If the standard Android framework density that is numerically closest to the physical density results in a screen size that is smaller than the smallest supported compatible screen size (320 dp width), device implementations SHOULD report the next lowest standard Android framework density.

Device implementations are STRONGLY RECOMMENDED to provide users a setting to change the display size. If there is an implementation to change the display size of the device, it MUST align with the AOSP implementation as indicated below:

  • The display size MUST NOT be scaled any larger than 1.5 times the native density or produce an effective minimum screen dimension smaller than 320dp (equivalent to resource qualifier sw320dp), whichever comes first.
  • Display size MUST NOT be scaled any smaller than 0.85 times the native density.
  • To ensure good usability and consistent font sizes, it is RECOMMENDED that the following scaling of Native Display options be provided (while complying with the limits specified above)
  • Small: 0.85x
  • Default: 1x (Native display scale)
  • Large: 1.15x
  • Larger: 1.3x
  • Largest 1.45x

7.1.2. Display Metrics

Device implementations MUST report correct values for all display metrics defined in android.util.DisplayMetrics and MUST report the same values regardless of whether the embedded or external screen is used as the default display.

7.1.3.螢幕方向

Devices MUST report which screen orientations they support (android.hardware.screen.portrait and/or android.hardware.screen.landscape) and MUST report at least one supported orientation. For example, a device with a fixed orientation landscape screen, such as a television or laptop, SHOULD only report android.hardware.screen.landscape.

Devices that report both screen orientations MUST support dynamic orientation by applications to either portrait or landscape screen orientation. That is, the device must respect the application's request for a specific screen orientation. Device implementations MAY select either portrait or landscape orientation as the default.

Devices MUST report the correct value for the device's current orientation, whenever queried via the android.content.res.Configuration.orientation, android.view.Display.getOrientation(), or other APIs.

Devices MUST NOT change the reported screen size or density when changing orientation.

7.1.4. 2D and 3D Graphics Acceleration

Device implementations MUST support both OpenGL ES 1.0 and 2.0, as embodied and detailed in the Android SDK documentations. Device implementations SHOULD support OpenGL ES 3.0, 3.1, or 3.2 on devices capable of supporting it. Device implementations MUST also support Android RenderScript , as detailed in the Android SDK documentation.

Device implementations MUST also correctly identify themselves as supporting OpenGL ES 1.0, OpenGL ES 2.0, OpenGL ES 3.0, OpenGL 3.1, or OpenGL 3.2.那是：

  • The managed APIs (such as via the GLES10.getString() method) MUST report support for OpenGL ES 1.0 and OpenGL ES 2.0.
  • The native C/C++ OpenGL APIs (APIs available to apps via libGLES_v1CM.so, libGLES_v2.so, or libEGL.so) MUST report support for OpenGL ES 1.0 and OpenGL ES 2.0.
  • Device implementations that declare support for OpenGL ES 3.0, 3.1, or 3.2 MUST support the corresponding managed APIs and include support for native C/C++ APIs. On device implementations that declare support for OpenGL ES 3.0, 3.1, or 3.2 libGLESv2.so MUST export the corresponding function symbols in addition to the OpenGL ES 2.0 function symbols.

Android provides an OpenGL ES extension pack with Java interfaces and native support for advanced graphics functionality such as tessellation and the ASTC texture compression format. Android device implementations MUST support the extension pack if the device supports OpenGL ES 3.2 and MAY support it otherwise. If the extension pack is supported in its entirety, the device MUST identify the support through the android.hardware.opengles.aep feature flag.

Also, device implementations MAY implement any desired OpenGL ES extensions. However, device implementations MUST report via the OpenGL ES managed and native APIs all extension strings that they do support, and conversely MUST NOT report extension strings that they do not support.

Note that Android includes support for applications to optionally specify that they require specific OpenGL texture compression formats. These formats are typically vendor-specific. Device implementations are not required by Android to implement any specific texture compression format. However, they SHOULD accurately report any texture compression formats that they do support, via the getString() method in the OpenGL API.

Android includes a mechanism for applications to declare that they want to enable hardware acceleration for 2D graphics at the Application, Activity, Window, or View level through the use of a manifest tag android:hardwareAccelerated or direct API calls.

Device implementations MUST enable hardware acceleration by default, and MUST disable hardware acceleration if the developer so requests by setting android:hardwareAccelerated="false” or disabling hardware acceleration directly through the Android View APIs.

In addition, device implementations MUST exhibit behavior consistent with the Android SDK documentation on hardware acceleration .

Android includes a TextureView object that lets developers directly integrate hardware-accelerated OpenGL ES textures as rendering targets in a UI hierarchy. Device implementations MUST support the TextureView API, and MUST exhibit consistent behavior with the upstream Android implementation.

Android includes support for EGL_ANDROID_RECORDABLE, an EGLConfig attribute that indicates whether the EGLConfig supports rendering to an ANativeWindow that records images to a video. Device implementations MUST support EGL_ANDROID_RECORDABLE extension.

7.1.5。 Legacy Application Compatibility Mode

Android specifies a “compatibility mode” in which the framework operates in a 'normal' screen size equivalent (320dp width) mode for the benefit of legacy applications not developed for old versions of Android that pre-date screen-size independence.

  • Android Automotive does not support legacy compatibility mode.
  • All other device implementations MUST include support for legacy application compatibility mode as implemented by the upstream Android open source code. That is, device implementations MUST NOT alter the triggers or thresholds at which compatibility mode is activated, and MUST NOT alter the behavior of the compatibility mode itself.

7.1.6。螢幕技術

The Android platform includes APIs that allow applications to render rich graphics to the display. Devices MUST support all of these APIs as defined by the Android SDK unless specifically allowed in this document.

  • Devices MUST support displays capable of rendering 16-bit color graphics and SHOULD support displays capable of 24-bit color graphics.
  • Devices MUST support displays capable of rendering animations.
  • The display technology used MUST have a pixel aspect ratio (PAR) between 0.9 and 1.15. That is, the pixel aspect ratio MUST be near square (1.0) with a 10 ~ 15% tolerance.

7.1.7. Secondary Displays

Android includes support for secondary display to enable media sharing capabilities and developer APIs for accessing external displays. If a device supports an external display either via a wired, wireless, or an embedded additional display connection then the device implementation MUST implement the display manager API as described in the Android SDK documentation.

7.2.輸入裝置

Devices MUST support a touchscreen or meet the requirements listed in 7.2.2 for non-touch navigation.

7.2.1.鍵盤

Android Watch and Android Automotive implementations MAY implement a soft keyboard. All other device implementations MUST implement a soft keyboard and:

Device implementations:

  • MUST include support for the Input Management Framework (which allows third-party developers to create Input Method Editors—ie soft keyboard) as detailed at http://developer.android.com .
  • MUST provide at least one soft keyboard implementation (regardless of whether a hard keyboard is present) except for Android Watch devices where the screen size makes it less reasonable to have a soft keyboard.
  • MAY include additional soft keyboard implementations.
  • MAY include a hardware keyboard.
  • MUST NOT include a hardware keyboard that does not match one of the formats specified in android.content.res.Configuration.keyboard (QWERTY or 12-key).

7.2.2. Non-touch Navigation

Android Television devices MUST support D-pad.

Device implementations:

  • MAY omit a non-touch navigation option (trackball, d-pad, or wheel) if the device implementation is not an Android Television device.
  • MUST report the correct value for android.content.res.Configuration.navigation .
  • MUST provide a reasonable alternative user interface mechanism for the selection and editing of text, compatible with Input Management Engines. The upstream Android open source implementation includes a selection mechanism suitable for use with devices that lack non-touch navigation inputs.

7.2.3. Navigation Keys

The availability and visibility requirement of the Home, Recents, and Back functions differ between device types as described in this section.

The Home, Recents, and Back functions (mapped to the key events KEYCODE_HOME, KEYCODE_APP_SWITCH, KEYCODE_BACK, respectively) are essential to the Android navigation paradigm and therefore:

  • Android Handheld device implementations MUST provide the Home, Recents, and Back functions.
  • Android Television device implementations MUST provide the Home and Back functions.
  • Android Watch device implementations MUST have the Home function available to the user, and the Back function except for when it is in UI_MODE_TYPE_WATCH .
  • Android Watch device implementations, and no other Android device types, MAY consume the long press event on the key event KEYCODE_BACK and omit it from being sent to the foreground application.
  • Android Automotive implementations MUST provide the Home function and MAY provide Back and Recent functions.
  • All other types of device implementations MUST provide the Home and Back functions.

These functions MAY be implemented via dedicated physical buttons (such as mechanical or capacitive touch buttons), or MAY be implemented using dedicated software keys on a distinct portion of the screen, gestures, touch panel, etc. Android supports both implementations. All of these functions MUST be accessible with a single action (eg tap, double-click or gesture) when visible.

Recents function, if provided, MUST have a visible button or icon unless hidden together with other navigation functions in full-screen mode. This does not apply to devices upgrading from earlier Android versions that have physical buttons for navigation and no recents key.

The Home and Back functions, if provided, MUST each have a visible button or icon unless hidden together with other navigation functions in full-screen mode or when the uiMode UI_MODE_TYPE_MASK is set to UI_MODE_TYPE_WATCH.

The Menu function is deprecated in favor of action bar since Android 4.0. Therefore the new device implementations shipping with Android 7.1 and later MUST NOT implement a dedicated physical button for the Menu function. Older device implementations SHOULD NOT implement a dedicated physical button for the Menu function, but if the physical Menu button is implemented and the device is running applications with targetSdkVersion > 10, the device implementation:

  • MUST display the action overflow button on the action bar when it is visible and the resulting action overflow menu popup is not empty. For a device implementation launched before Android 4.4 but upgrading to Android 7.1, this is RECOMMENDED.
  • MUST NOT modify the position of the action overflow popup displayed by selecting the overflow button in the action bar.
  • MAY render the action overflow popup at a modified position on the screen when it is displayed by selecting the physical menu button.

For backwards compatibility, device implementations MUST make the Menu function available to applications when targetSdkVersion is less than 10, either by a physical button, a software key, or gestures. This Menu function should be presented unless hidden together with other navigation functions.

Android device implementations supporting the Assist action and/or VoiceInteractionService MUST be able to launch an assist app with a single interaction (eg tap, double-click, or gesture) when other navigation keys are visible. It is STRONGLY RECOMMENDED to use long press on home as this interaction. The designated interaction MUST launch the user-selected assist app, in other words the app that implements a VoiceInteractionService, or an activity handling the ACTION_ASSIST intent.

Device implementations MAY use a distinct portion of the screen to display the navigation keys, but if so, MUST meet these requirements:

  • Device implementation navigation keys MUST use a distinct portion of the screen, not available to applications, and MUST NOT obscure or otherwise interfere with the portion of the screen available to applications.
  • Device implementations MUST make available a portion of the display to applications that meets the requirements defined in section 7.1.1 .
  • Device implementations MUST display the navigation keys when applications do not specify a system UI mode, or specify SYSTEM_UI_FLAG_VISIBLE.
  • Device implementations MUST present the navigation keys in an unobtrusive “low profile” (eg. dimmed) mode when applications specify SYSTEM_UI_FLAG_LOW_PROFILE.
  • Device implementations MUST hide the navigation keys when applications specify SYSTEM_UI_FLAG_HIDE_NAVIGATION.

7.2.4. Touchscreen Input

Android Handhelds and Watch Devices MUST support touchscreen input.

Device implementations SHOULD have a pointer input system of some kind (either mouse-like or touch). However, if a device implementation does not support a pointer input system, it MUST NOT report the android.hardware.touchscreen or android.hardware.faketouch feature constant. Device implementations that do include a pointer input system:

  • SHOULD support fully independently tracked pointers, if the device input system supports multiple pointers.
  • MUST report the value of android.content.res.Configuration.touchscreen corresponding to the type of the specific touchscreen on the device.

Android includes support for a variety of touchscreens, touch pads, and fake touch input devices. Touchscreen-based device implementations are associated with a display such that the user has the impression of directly manipulating items on screen. Since the user is directly touching the screen, the system does not require any additional affordances to indicate the objects being manipulated. In contrast, a fake touch interface provides a user input system that approximates a subset of touchscreen capabilities. For example, a mouse or remote control that drives an on-screen cursor approximates touch, but requires the user to first point or focus then click. Numerous input devices like the mouse, trackpad, gyro-based air mouse, gyro-pointer, joystick, and multi-touch trackpad can support fake touch interactions. Android includes the feature constant android.hardware.faketouch, which corresponds to a high-fidelity non-touch (pointer-based) input device such as a mouse or trackpad that can adequately emulate touch-based input (including basic gesture support), and indicates that the device supports an emulated subset of touchscreen functionality. Device implementations that declare the fake touch feature MUST meet the fake touch requirements in section 7.2.5 .

Device implementations MUST report the correct feature corresponding to the type of input used. Device implementations that include a touchscreen (single-touch or better) MUST report the platform feature constant android.hardware.touchscreen. Device implementations that report the platform feature constant android.hardware.touchscreen MUST also report the platform feature constant android.hardware.faketouch. Device implementations that do not include a touchscreen (and rely on a pointer device only) MUST NOT report any touchscreen feature, and MUST report only android.hardware.faketouch if they meet the fake touch requirements in section 7.2.5 .

7.2.5. Fake Touch Input

Device implementations that declare support for android.hardware.faketouch:

  • MUST report the absolute X and Y screen positions of the pointer location and display a visual pointer on the screen.
  • MUST report touch event with the action code that specifies the state change that occurs on the pointer going down or up on the screen .
  • MUST support pointer down and up on an object on the screen, which allows users to emulate tap on an object on the screen.
  • MUST support pointer down, pointer up, pointer down then pointer up in the same place on an object on the screen within a time threshold, which allows users to emulate double tap on an object on the screen.
  • MUST support pointer down on an arbitrary point on the screen, pointer move to any other arbitrary point on the screen, followed by a pointer up, which allows users to emulate a touch drag.
  • MUST support pointer down then allow users to quickly move the object to a different position on the screen and then pointer up on the screen, which allows users to fling an object on the screen.

Devices that declare support for android.hardware.faketouch.multitouch.distinct MUST meet the requirements for faketouch above, and MUST also support distinct tracking of two or more independent pointer inputs.

7.2.6。 Game Controller Support

Android Television device implementations MUST support button mappings for game controllers as listed below. The upstream Android implementation includes implementation for game controllers that satisfies this requirement.

7.2.6.1. Button Mappings

Android Television device implementations MUST support the following key mappings:

按鈕HID Usage 2安卓按鈕
甲1 0x09 0x0001 KEYCODE_BUTTON_A (96)
B 1 0x09 0x0002 KEYCODE_BUTTON_B (97)
X 1 0x09 0x0004 KEYCODE_BUTTON_X (99)
Y 1 0x09 0x0005 KEYCODE_BUTTON_Y (100)
D-pad up 1
D-pad down 1		 0x01 0x0039 3 AXIS_HAT_Y 4
D-pad left 1
D-pad right 1		 0x01 0x0039 3 AXIS_HAT_X 4
Left shoulder button 1 0x09 0x0007 KEYCODE_BUTTON_L1 (102)
Right shoulder button 1 0x09 0x0008 KEYCODE_BUTTON_R1 (103)
Left stick click 1 0x09 0x000E KEYCODE_BUTTON_THUMBL (106)
Right stick click 1 0x09 0x000F KEYCODE_BUTTON_THUMBR (107)
首頁1 0x0c 0x0223 KEYCODE_HOME (3)
Back 1 0x0c 0x0224 KEYCODE_BACK (4)

1 KeyEvent

2 The above HID usages must be declared within a Game pad CA (0x01 0x0005).

3 This usage must have a Logical Minimum of 0, a Logical Maximum of 7, a Physical Minimum of 0, a Physical Maximum of 315, Units in Degrees, and a Report Size of 4. The logical value is defined to be the clockwise rotation away from the vertical axis; for example, a logical value of 0 represents no rotation and the up button being pressed, while a logical value of 1 represents a rotation of 45 degrees and both the up and left keys being pressed.

4 MotionEvent

Analog Controls 1 HID Usage安卓按鈕
左扳機0x02 0x00C5 AXIS_LTRIGGER
右邊扳機0x02 0x00C4 AXIS_RTRIGGER
Left Joystick 0x01 0x0030
0x01 0x0031		 AXIS_X
AXIS_Y
Right Joystick 0x01 0x0032
0x01 0x0035		 AXIS_Z
AXIS_RZ

1 MotionEvent

7.2.7.遙控

Android Television device implementations SHOULD provide a remote control to allow users to access the TV interface. The remote control MAY be a physical remote or can be a software-based remote that is accessible from a mobile phone or tablet. The remote control MUST meet the requirements defined below.

  • Search affordance . Device implementations MUST fire KEYCODE_SEARCH (or KEYCODE_ASSIST if the device supports an assistant) when the user invokes voice search on either the physical or software-based remote.
  • 導航。 All Android Television remotes MUST include Back, Home, and Select buttons and support for D-pad events .

7.3.感應器

Android includes APIs for accessing a variety of sensor types. Devices implementations generally MAY omit these sensors, as provided for in the following subsections. If a device includes a particular sensor type that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation and the Android Open Source documentation on sensors . For example, device implementations:

  • MUST accurately report the presence or absence of sensors per the android.content.pm.PackageManager class.
  • MUST return an accurate list of supported sensors via the SensorManager.getSensorList() and similar methods.
  • MUST behave reasonably for all other sensor APIs (for example, by returning true or false as appropriate when applications attempt to register listeners, not calling sensor listeners when the corresponding sensors are not present; etc.).
  • MUST report all sensor measurements using the relevant International System of Units (metric) values for each sensor type as defined in the Android SDK documentation.
  • SHOULD report the event time in nanoseconds as defined in the Android SDK documentation, representing the time the event happened and synchronized with the SystemClock.elapsedRealtimeNano() clock. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to the future platform releases where this might become a REQUIRED component. The synchronization error SHOULD be below 100 milliseconds.
  • MUST report sensor data with a maximum latency of 100 milliseconds + 2 * sample_time for the case of a sensor streamed with a minimum required latency of 5 ms + 2 * sample_time when the application processor is active. This delay does not include any filtering delays.
  • MUST report the first sensor sample within 400 milliseconds + 2 * sample_time of the sensor being activated. It is acceptable for this sample to have an accuracy of 0.

The list above is not comprehensive; the documented behavior of the Android SDK and the Android Open Source Documentations on sensors is to be considered authoritative.

Some sensor types are composite, meaning they can be derived from data provided by one or more other sensors. (Examples include the orientation sensor and the linear acceleration sensor.) Device implementations SHOULD implement these sensor types, when they include the prerequisite physical sensors as described in sensor types . If a device implementation includes a composite sensor it MUST implement the sensor as described in the Android Open Source documentation on composite sensors .

Some Android sensors support a “continuous” trigger mode , which returns data continuously.為 any API indicated by the Android SDK documentation to be a continuous sensor, device implementations MUST continuously provide periodic data samples that SHOULD have a jitter below 3%, where jitter is definal reportas the stand valviues the value valviues value valviues value.事件。

Note that the device implementations MUST ensure that the sensor event stream MUST NOT prevent the device CPU from entering a suspend state or waking up from a suspend state.

Finally, when several sensors are activated, the power consumption SHOULD NOT exceed the sum of the individual sensor's reported power consumption.

7.3.1.加速度計

Device implementations SHOULD include a 3-axis accelerometer. Android Handheld devices, Android Automotive implementations, and Android Watch devices are STRONGLY RECOMMENDED to include this sensor. If a device implementation does include a 3-axis accelerometer, it:

  • MUST implement and report TYPE_ACCELEROMETER sensor .
  • MUST be able to report events up to a frequency of at least 50 Hz for Android Watch devices as such devices have a stricter power constraint and 100 Hz for all other device types.
  • SHOULD report events up to at least 200 Hz.
  • MUST comply with the Android sensor coordinate system as detailed in the Android APIs. Android Automotive implementations MUST comply with the Android car sensor coordinate system .
  • MUST be capable of measuring from freefall up to four times the gravity (4g) or more on any axis.
  • MUST have a resolution of at least 12-bits and SHOULD have a resolution of at least 16-bits.
  • SHOULD be calibrated while in use if the characteristics changes over the life cycle and compensated, and preserve the compensation parameters between device reboots.
  • SHOULD be temperature compensated.
  • MUST have a standard deviation no greater than 0.05 m/s^, where the standard deviation should be calculated on a per axis basis on samples collected over a period of at least 3 seconds at the fastest sampling rate.
  • SHOULD implement the TYPE_SIGNIFICANT_MOTION, TYPE_TILT_DETECTOR, TYPE_STEP_DETECTOR, TYPE_STEP_COUNTER composite sensors as described in the Android SDK document. Existing and new Android devices are STRONGLY RECOMMENDED to implement the TYPE_SIGNIFICANT_MOTION composite sensor. If any of these sensors are implemented, the sum of their power consumption MUST always be less than 4 mW and SHOULD each be below 2 mW and 0.5 mW for when the device is in a dynamic or static condition.
  • If a gyroscope sensor is included, MUST implement the TYPE_GRAVITY and TYPE_LINEAR_ACCELERATION composite sensors and SHOULD implement the TYPE_GAME_ROTATION_VECTOR composite sensor. Existing and new Android devices are STRONGLY RECOMMENDED to implement the TYPE_GAME_ROTATION_VECTOR sensor.
  • MUST implement a TYPE_ROTATION_VECTOR composite sensor, if a gyroscope sensor and a magnetometer sensor is also included.

7.3.2.磁力計

Device implementations SHOULD include a 3-axis magnetometer (compass). If a device does include a 3-axis magnetometer, it:

  • MUST implement the TYPE_MAGNETIC_FIELD sensor and SHOULD also implement TYPE_MAGNETIC_FIELD_UNCALIBRATED sensor. Existing and new Android devices are STRONGLY RECOMMENDED to implement the TYPE_MAGNETIC_FIELD_UNCALIBRATED sensor.
  • MUST be able to report events up to a frequency of at least 10 Hz and SHOULD report events up to at least 50 Hz.
  • MUST comply with the Android sensor coordinate system as detailed in the Android APIs.
  • MUST be capable of measuring between -900 µT and +900 µT on each axis before saturating.
  • MUST have a hard iron offset value less than 700 µT and SHOULD have a value below 200 µT, by placing the magnetometer far from dynamic (current-induced) and static (magnet-induced) magnetic fields.
  • MUST have a resolution equal or denser than 0.6 µT and SHOULD have a resolution equal or denser than 0.2 µT.
  • SHOULD be temperature compensated.
  • MUST support online calibration and compensation of the hard iron bias, and preserve the compensation parameters between device reboots.
  • MUST have the soft iron compensation applied—the calibration can be done either while in use or during the production of the device.
  • SHOULD have a standard deviation, calculated on a per axis basis on samples collected over a period of at least 3 seconds at the fastest sampling rate, no greater than 0.5 µT.
  • MUST implement a TYPE_ROTATION_VECTOR composite sensor, if an accelerometer sensor and a gyroscope sensor is also included.
  • MAY implement the TYPE_GEOMAGNETIC_ROTATION_VECTOR sensor if an accelerometer sensor is also implemented. However if implemented, it MUST consume less than 10 mW and SHOULD consume less than 3 mW when the sensor is registered for batch mode at 10 Hz.

7.3.3.全球定位系統

Device implementations SHOULD include a GPS/GNSS receiver. If a device implementation does include a GPS/GNSS receiver and reports the capability to applications through the android.hardware.location.gps feature flag:

  • It is STRONGLY RECOMMENDED that the device continue to deliver normal GPS/GNSS outputs to applications during an emergency phone call and that location output not be blocked during an emergency phone call.
  • It MUST support location outputs at a rate of at least 1 Hz when requested via LocationManager#requestLocationUpdate .
  • It MUST be able to determine the location in open-sky conditions (strong signals, negligible multipath, HDOP < 2) within 10 seconds (fast time to first fix), when connected to a 0.5 Mbps or faster data speed internet connection. This requirement is typically met by the use of some form of Assisted or Predicted GPS/GNSS technique to minimize GPS/GNSS lock-on time (Assistance data includes Reference Time, Reference Location and Satellite Ephemeris/Clock).
    • After making such a location calculation, it is STRONGLY RECOMMENDED for the device to be able to determine its location, in open sky, within 10 seconds, when location requests are restarted, up to an hour after the initial location calculation, even when the subsequent request is made without a data connection, and/or after a power cycle.
  • In open sky conditions after determining the location, while stationary or moving with less than 1 meter per second squared of acceleration:
    • It MUST be able to determine location within 20 meters, and speed within 0.5 meters per second, at least 95% of the time.
    • It MUST simultaneously track and report via GnssStatus.Callback at least 8 satellites from one constellation.
    • It SHOULD be able to simultaneously track at least 24 satellites, from multiple constellations (eg GPS + at least one of Glonass, Beidou, Galileo).
  • It MUST report the GNSS technology generation through the test API 'getGnssYearOfHardware'.
  • It is STRONGLY RECOMMENDED to meet and MUST meet all requirements below if the GNSS technology generation is reported as the year "2016" or newer.
    • It MUST report GPS measurements, as soon as they are found, even if a location calculated from GPS/GNSS is not yet reported.
    • It MUST report GPS pseudoranges and pseudorange rates, that, in open-sky conditions after determining the location, while stationary or moving with less than 0.2 meter per second squared of acceleration, are sufficient to calculate position within 20 meters, and speed within 0.2 meters per second, at least 95% of the time.

Note that while some of the GPS requirements above are stated as STRONGLY RECOMMENDED, the Compatibility Definition for the next major version is expected to change these to a MUST.

7.3.4.陀螺儀

Device implementations SHOULD include a gyroscope (angular change sensor). Devices SHOULD NOT include a gyroscope sensor unless a 3-axis accelerometer is also included. If a device implementation includes a gyroscope, it:

  • MUST implement the TYPE_GYROSCOPE sensor and SHOULD also implement TYPE_GYROSCOPE_UNCALIBRATED sensor. Existing and new Android devices are STRONGLY RECOMMENDED to implement the SENSOR_TYPE_GYROSCOPE_UNCALIBRATED sensor.
  • MUST be capable of measuring orientation changes up to 1,000 degrees per second.
  • MUST be able to report events up to a frequency of at least 50 Hz for Android Watch devices as such devices have a stricter power constraint and 100 Hz for all other device types.
  • SHOULD report events up to at least 200 Hz.
  • MUST have a resolution of 12-bits or more and SHOULD have a resolution of 16-bits or more.
  • MUST be temperature compensated.
  • MUST be calibrated and compensated while in use, and preserve the compensation parameters between device reboots.
  • MUST have a variance no greater than 1e-7 rad^2 / s^2 per Hz (variance per Hz, or rad^2 / s). The variance is allowed to vary with the sampling rate, but must be constrained by this value. In other words, if you measure the variance of the gyro at 1 Hz sampling rate it should be no greater than 1e-7 rad^2/s^2.
  • MUST implement a TYPE_ROTATION_VECTOR composite sensor, if an accelerometer sensor and a magnetometer sensor is also included.
  • If an accelerometer sensor is included, MUST implement the TYPE_GRAVITY and TYPE_LINEAR_ACCELERATION composite sensors and SHOULD implement the TYPE_GAME_ROTATION_VECTOR composite sensor. Existing and new Android devices are STRONGLY RECOMMENDED to implement the TYPE_GAME_ROTATION_VECTOR sensor.

7.3.5.晴雨表

Device implementations SHOULD include a barometer (ambient air pressure sensor). If a device implementation includes a barometer, it:

  • MUST implement and report TYPE_PRESSURE sensor.
  • MUST be able to deliver events at 5 Hz or greater.
  • MUST have adequate precision to enable estimating altitude.
  • MUST be temperature compensated.

7.3.6。溫度計

Device implementations MAY include an ambient thermometer (temperature sensor). If present, it MUST be defined as SENSOR_TYPE_AMBIENT_TEMPERATURE and it MUST measure the ambient (room) temperature in degrees Celsius.

Device implementations MAY but SHOULD NOT include a CPU temperature sensor. If present, it MUST be defined as SENSOR_TYPE_TEMPERATURE, it MUST measure the temperature of the device CPU, and it MUST NOT measure any other temperature. Note the SENSOR_TYPE_TEMPERATURE sensor type was deprecated in Android 4.0.

For Android Automotive implementations, SENSOR_TYPE_AMBIENT_TEMPERATURE MUST measure the temperature inside the vehicle cabin.

7.3.7. Photometer

Device implementations MAY include a photometer (ambient light sensor).

7.3.8.接近感測器

Device implementations MAY include a proximity sensor. Devices that can make a voice call and indicate any value other than PHONE_TYPE_NONE in getPhoneType SHOULD include a proximity sensor. If a device implementation does include a proximity sensor, it:

  • MUST measure the proximity of an object in the same direction as the screen. That is, the proximity sensor MUST be oriented to detect objects close to the screen, as the primary intent of this sensor type is to detect a phone in use by the user. If a device implementation includes a proximity sensor with any other orientation, it MUST NOT be accessible through this API.
  • MUST have 1-bit of accuracy or more.

7.3.9. High Fidelity Sensors

Device implementations supporting a set of higher quality sensors that can meet all the requirements listed in this section MUST identify the support through the android.hardware.sensor.hifi_sensors feature flag.

A device declaring android.hardware.sensor.hifi_sensors MUST support all of the following sensor types meeting the quality requirements as below:

  • SENSOR_TYPE_ACCELEROMETER
    • MUST have a measurement range between at least -8g and +8g.
    • MUST have a measurement resolution of at least 1024 LSB/G.
    • MUST have a minimum measurement frequency of 12.5 Hz or lower.
    • MUST have a maximum measurement frequency of 400 Hz or higher.
    • MUST have a measurement noise not above 400 uG/√Hz.
    • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 3000 sensor events.
    • MUST have a batching power consumption not worse than 3 mW.
    • SHOULD have a stationary noise bias stability of \<15 μg √Hz from 24hr static dataset.
    • SHOULD have a bias change vs. temperature of ≤ +/- 1mg / °C.
    • SHOULD have a best-fit line non-linearity of ≤ 0.5%, and sensitivity change vs. temperature of ≤ 0.03%/C°.

  • SENSOR_TYPE_GYROSCOPE

    • MUST have a measurement range between at least -1000 and +1000 dps.
    • MUST have a measurement resolution of at least 16 LSB/dps.
    • MUST have a minimum measurement frequency of 12.5 Hz or lower.
    • MUST have a maximum measurement frequency of 400 Hz or higher.
    • MUST have a measurement noise not above 0.014°/s/√Hz.
    • SHOULD have a stationary bias stability of < 0.0002 °/s √Hz from 24-hour static dataset.
    • SHOULD have a bias change vs. temperature of ≤ +/- 0.05 °/ s / °C.
    • SHOULD have a sensitivity change vs. temperature of ≤ 0.02% / °C.
    • SHOULD have a best-fit line non-linearity of ≤ 0.2%.
    • SHOULD have a noise density of ≤ 0.007 °/s/√Hz.

  • SENSOR_TYPE_GYROSCOPE_UNCALIBRATED with the same quality requirements as SENSOR_TYPE_GYROSCOPE.

  • SENSOR_TYPE_GEOMAGNETIC_FIELD
    • MUST have a measurement range between at least -900 and +900 uT.
    • MUST have a measurement resolution of at least 5 LSB/uT.
    • MUST have a minimum measurement frequency of 5 Hz or lower.
    • MUST have a maximum measurement frequency of 50 Hz or higher.
    • MUST have a measurement noise not above 0.5 uT.
  • SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED with the same quality requirements as SENSOR_TYPE_GEOMAGNETIC_FIELD and in addition:
    • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 600 sensor events.
  • SENSOR_TYPE_PRESSURE
    • MUST have a measurement range between at least 300 and 1100 hPa.
    • MUST have a measurement resolution of at least 80 LSB/hPa.
    • MUST have a minimum measurement frequency of 1 Hz or lower.
    • MUST have a maximum measurement frequency of 10 Hz or higher.
    • MUST have a measurement noise not above 2 Pa/√Hz.
    • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 300 sensor events.
    • MUST have a batching power consumption not worse than 2 mW.
  • SENSOR_TYPE_GAME_ROTATION_VECTOR
    • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 300 sensor events.
    • MUST have a batching power consumption not worse than 4 mW.
  • SENSOR_TYPE_SIGNIFICANT_MOTION
    • MUST have a power consumption not worse than 0.5 mW when device is static and 1.5 mW when device is moving.
  • SENSOR_TYPE_STEP_DETECTOR
    • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 100 sensor events.
    • MUST have a power consumption not worse than 0.5 mW when device is static and 1.5 mW when device is moving.
    • MUST have a batching power consumption not worse than 4 mW.
  • SENSOR_TYPE_STEP_COUNTER
    • MUST have a power consumption not worse than 0.5 mW when device is static and 1.5 mW when device is moving.
  • SENSOR_TILT_DETECTOR
    • MUST have a power consumption not worse than 0.5 mW when device is static and 1.5 mW when device is moving.

Also such a device MUST meet the following sensor subsystem requirements:

  • The event timestamp of the same physical event reported by the Accelerometer, Gyroscope sensor and Magnetometer MUST be within 2.5 milliseconds of each other.
  • The Gyroscope sensor event timestamps MUST be on the same time base as the camera subsystem and within 1 milliseconds of error.
  • High Fidelity sensors MUST deliver samples to applications within 5 milliseconds from the time when the data is available on the physical sensor to the application.
  • The power consumption MUST not be higher than 0.5 mW when device is static and 2.0 mW when device is moving when any combination of the following sensors are enabled:
    • SENSOR_TYPE_SIGNIFICANT_MOTION
    • SENSOR_TYPE_STEP_DETECTOR
    • SENSOR_TYPE_STEP_COUNTER
    • SENSOR_TILT_DETECTORS

Note that all power consumption requirements in this section do not include the power consumption of the Application Processor. It is inclusive of the power drawn by the entire sensor chain—the sensor, any supporting circuitry, any dedicated sensor processing system, etc.

The following sensor types MAY also be supported on a device implementation declaring android.hardware.sensor.hifi_sensors, but if these sensor types are present they MUST meet the following minimum buffering capability requirement:

  • SENSOR_TYPE_PROXIMITY: 100 sensor events

7.3.10.指紋感應器

Device implementations with a secure lock screen SHOULD include a fingerprint sensor. If a device implementation includes a fingerprint sensor and has a corresponding API for third-party developers, it:

  • MUST declare support for the android.hardware.fingerprint feature.
  • MUST fully implement the corresponding API as described in the Android SDK documentation.
  • MUST have a false acceptance rate not higher than 0.002%.
  • Is STRONGLY RECOMMENDED to have a false rejection rate of less than 10%, as measured on the device
  • Is STRONGLY RECOMMENDED to have a latency below 1 second, measured from when the fingerprint sensor is touched until the screen is unlocked, for one enrolled finger.
  • MUST rate limit attempts for at least 30 seconds after five false trials for fingerprint verification.
  • MUST have a hardware-backed keystore implementation, and perform the fingerprint matching in a Trusted Execution Environment (TEE) or on a chip with a secure channel to the TEE.
  • MUST have all identifiable fingerprint data encrypted and cryptographically authenticated such that they cannot be acquired, read or altered outside of the Trusted Execution Environment (TEE) as documented in the implementation guidelines on the Android Open Source Project site.
  • MUST prevent adding a fingerprint without first establishing a chain of trust by having the user confirm existing or add a new device credential (PIN/pattern/password) that's secured by TEE; the Android Open Source Project implementation provides the mechanism in the framework to do so.
  • MUST NOT enable 3rd-party applications to distinguish between individual fingerprints.
  • MUST honor the DevicePolicyManager.KEYGUARD_DISABLE_FINGERPRINT flag.
  • MUST, when upgraded from a version earlier than Android 6.0, have the fingerprint data securely migrated to meet the above requirements or removed.
  • SHOULD use the Android Fingerprint icon provided in the Android Open Source Project.

7.3.11. Android Automotive-only sensors

Automotive-specific sensors are defined in the android.car.CarSensorManager API .

7.3.11.1. Current Gear

Android Automotive implementations SHOULD provide current gear as SENSOR_TYPE_GEAR.

7.3.11.2. Day Night Mode

Android Automotive implementations MUST support day/night mode defined as SENSOR_TYPE_NIGHT. The value of this flag MUST be consistent with dashboard day/night mode and SHOULD be based on ambient light sensor input. The underlying ambient light sensor MAY be the same as Photometer .

7.3.11.3.駕駛狀態

Android Automotive implementations MUST support driving status defined as SENSOR_TYPE_DRIVING_STATUS, with a default value of DRIVE_STATUS_UNRESTRICTED when the vehicle is fully stopped and parked. It is the responsibility of device manufacturers to configure SENSOR_TYPE_DRIVING_STATUS in compliance with all laws and regulations that apply to markets where the product is shipping.

7.3.11.4. Wheel Speed

Android Automotive implementations MUST provide vehicle speed defined as SENSOR_TYPE_CAR_SPEED.

7.3.12. Pose Sensor

Device implementations MAY support pose sensor with 6 degrees of freedom. Android Handheld devices are RECOMMENDED to support this sensor. If a device implementation does support pose sensor with 6 degrees of freedom, it:

  • MUST implement and report TYPE_POSE_6DOF sensor.
  • MUST be more accurate than the rotation vector alone.

7.4.數據連接

7.4.1.電話

“Telephony” as used by the Android APIs and this document refers specifically to hardware related to placing voice calls and sending SMS messages via a GSM or CDMA network. While these voice calls may or may not be packet-switched, they are for the purposes of Android considered independent of any data connectivity that may be implemented using the same network. In other words, the Android “telephony” functionality and APIs refer specifically to voice calls and SMS. For instance, device implementations that cannot place calls or send/receive SMS messages MUST NOT report the android.hardware.telephony feature or any subfeatures, regardless of whether they use a cellular network for data connectivity.

Android MAY be used on devices that do not include telephony hardware. That is, Android is compatible with devices that are not phones. However, if a device implementation does include GSM or CDMA telephony, it MUST implement full support for the API for that technology. Device implementations that do not include telephony hardware MUST implement the full APIs as no-ops.

7.4.1.1. Number Blocking Compatibility

Android Telephony device implementations MUST include number blocking support and:

  • MUST fully implement BlockedNumberContract and the corresponding API as described in the SDK documentation.
  • MUST block all calls and messages from a phone number in 'BlockedNumberProvider' without any interaction with apps. The only exception is when number blocking is temporarily lifted as described in the SDK documentation.
  • MUST NOT write to the platform call log provider for a blocked call.
  • MUST NOT write to the Telephony provider for a blocked message.
  • MUST implement a blocked numbers management UI, which is opened with the intent returned by TelecomManager.createManageBlockedNumbersIntent() method.
  • MUST NOT allow secondary users to view or edit the blocked numbers on the device as the Android platform assumes the primary user to have full control of the telephony services, a single instance, on the device. All blocking related UI MUST be hidden for secondary users and the blocked list MUST still be respected.
  • SHOULD migrate the blocked numbers into the provider when a device updates to Android 7.0.

7.4.2. IEEE 802.11 (Wi-Fi)

All Android device implementations SHOULD include support for one or more forms of 802.11. If a device implementation does include support for 802.11 and exposes the functionality to a third-party application, it MUST implement the corresponding Android API and:

  • MUST report the hardware feature flag android.hardware.wifi.
  • MUST implement the multicast API as described in the SDK documentation.
  • MUST support multicast DNS (mDNS) and MUST NOT filter mDNS packets (224.0.0.251) at any time of operation including:
    • Even when the screen is not in an active state.
    • For Android Television device implementations, even when in standby power states.

7.4.2.1.無線直連

Device implementations SHOULD include support for Wi-Fi Direct (Wi-Fi peer-to-peer). If a device implementation does include support for Wi-Fi Direct, it MUST implement the corresponding Android API as described in the SDK documentation. If a device implementation includes support for Wi-Fi Direct, then it:

  • MUST report the hardware feature android.hardware.wifi.direct.
  • MUST support regular Wi-Fi operation.
  • SHOULD support concurrent Wi-Fi and Wi-Fi Direct operation.

Device implementations SHOULD include support for Wi-Fi Tunneled Direct Link Setup (TDLS) as described in the Android SDK Documentation. If a device implementation does include support for TDLS and TDLS is enabled by the WiFiManager API, the device:

  • SHOULD use TDLS only when it is possible AND beneficial.
  • SHOULD have some heuristic and NOT use TDLS when its performance might be worse than going through the Wi-Fi access point.

7.4.3.藍牙

Android Watch implementations MUST support Bluetooth. Android Television implementations MUST support Bluetooth and Bluetooth LE. Android Automotive implementations MUST support Bluetooth and SHOULD support Bluetooth LE.

Device implementations that support android.hardware.vr.high_performance feature MUST support Bluetooth 4.2 and Bluetooth LE Data Length Extension.

Android includes support for Bluetooth and Bluetooth Low Energy . Device implementations that include support for Bluetooth and Bluetooth Low Energy MUST declare the relevant platform features (android.hardware.bluetooth and android.hardware.bluetooth_le respectively) and implement the platform APIs. Device implementations SHOULD implement relevant Bluetooth profiles such as A2DP, AVCP, OBEX, etc. as appropriate for the device.

Android Automotive implementations SHOULD support Message Access Profile (MAP). Android Automotive implementations MUST support the following Bluetooth profiles:

  • Phone calling over Hands-Free Profile (HFP).
  • Media playback over Audio Distribution Profile (A2DP).
  • Media playback control over Remote Control Profile (AVRCP).
  • Contact sharing using the Phone Book Access Profile (PBAP).

Device implementations including support for Bluetooth Low Energy:

  • MUST declare the hardware feature android.hardware.bluetooth_le.
  • MUST enable the GATT (generic attribute profile) based Bluetooth APIs as described in the SDK documentation and android.bluetooth .
  • are STRONGLY RECOMMENDED to implement a Resolvable Private Address (RPA) timeout no longer than 15 minutes and rotate the address at timeout to protect user privacy.
  • SHOULD support offloading of the filtering logic to the bluetooth chipset when implementing the ScanFilter API , and MUST report the correct value of where the filtering logic is implemented whenever queried via the android.bluetooth.BluetoothAdapter.isOffloadedFilteringSupported() method.
  • SHOULD support offloading of the batched scanning to the bluetooth chipset, but if not supported, MUST report 'false' whenever queried via the android.bluetooth.BluetoothAdapter.isOffloadedScanBatchingSupported() method.
  • SHOULD support multi advertisement with at least 4 slots, but if not supported, MUST report 'false' whenever queried via the android.bluetooth.BluetoothAdapter.isMultipleAdvertisementSupported() method.

7.4.4. Near-Field Communications

Device implementations SHOULD include a transceiver and related hardware for Near-Field Communications (NFC). If a device implementation does include NFC hardware and plans to make it available to third-party apps, then it:

  • MUST report the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method .
  • MUST be capable of reading and writing NDEF messages via the following NFC standards:
    • MUST be capable of acting as an NFC Forum reader/writer (as defined by the NFC Forum technical specification NFCForum-TS-DigitalProtocol-1.0) via the following NFC standards:
      • NfcA (ISO14443-3A)
      • NfcB (ISO14443-3B)
      • NfcF (JIS X 6319-4)
      • IsoDep (ISO 14443-4)
      • NFC Forum Tag Types 1, 2, 3, 4 (defined by the NFC Forum)
    • STRONGLY RECOMMENDED to be capable of reading and writing NDEF messages as well as raw data via the following NFC standards. Note that while the NFC standards below are stated as STRONGLY RECOMMENDED, the Compatibility Definition for a future version is planned to change these to MUST. These standards are optional in this version but will be required in future versions. Existing and new devices that run this version of Android are very strongly encouraged to meet these requirements now so they will be able to upgrade to the future platform releases.
      • NfcV (ISO 15693)
    • SHOULD be capable of reading the barcode and URL (if encoded) of Thinfilm NFC Barcode products.
    • MUST be capable of transmitting and receiving data via the following peer-to-peer standards and protocols:
      • ISO 18092
      • LLCP 1.2 (defined by the NFC Forum)
      • SDP 1.0 (defined by the NFC Forum)
      • NDEF Push Protocol
      • SNEP 1.0 (defined by the NFC Forum)
    • MUST include support for Android Beam .
    • MUST implement the SNEP default server. Valid NDEF messages received by the default SNEP server MUST be dispatched to applications using the android.nfc.ACTION_NDEF_DISCOVERED intent. Disabling Android Beam in settings MUST NOT disable dispatch of incoming NDEF message.
    • MUST honor the android.settings.NFCSHARING_SETTINGS intent to show NFC sharing settings .
    • MUST implement the NPP server. Messages received by the NPP server MUST be processed the same way as the SNEP default server.
    • MUST implement a SNEP client and attempt to send outbound P2P NDEF to the default SNEP server when Android Beam is enabled. If no default SNEP server is found then the client MUST attempt to send to an NPP server.
    • MUST allow foreground activities to set the outbound P2P NDEF message using android.nfc.NfcAdapter.setNdefPushMessage, and android.nfc.NfcAdapter.setNdefPushMessageCallback, and android.nfc.NfcAdapter.enableForegroundNdefPush.
    • SHOULD use a gesture or on-screen confirmation, such as 'Touch to Beam', before sending outbound P2P NDEF messages.
    • SHOULD enable Android Beam by default and MUST be able to send and receive using Android Beam, even when another proprietary NFC P2p mode is turned on.
    • MUST support NFC Connection handover to Bluetooth when the device supports Bluetooth Object Push Profile. Device implementations MUST support connection handover to Bluetooth when using android.nfc.NfcAdapter.setBeamPushUris, by implementing the “ Connection Handover version 1.2 ” and “ Bluetooth Secure Simple Pairing Using NFC version 1.0 ” specs from the NFC Forum. Such an implementation MUST implement the handover LLCP service with service name “urn:nfc:sn:handover” for exchanging the handover request/select records over NFC, and it MUST use the Bluetooth Object Push Profile for the actual Bluetooth data transfer. For legacy reasons (to remain compatible with Android 4.1 devices), the implementation SHOULD still accept SNEP GET requests for exchanging the handover request/select records over NFC. However an implementation itself SHOULD NOT send SNEP GET requests for performing connection handover.
    • MUST poll for all supported technologies while in NFC discovery mode.
    • SHOULD be in NFC discovery mode while the device is awake with the screen active and the lock-screen unlocked.

(Note that publicly available links are not available for the JIS, ISO, and NFC Forum specifications cited above.)

Android includes support for NFC Host Card Emulation (HCE) mode. If a device implementation does include an NFC controller chipset capable of HCE (for NfcA and/or NfcB) and it supports Application ID (AID) routing, then it:

  • MUST report the android.hardware.nfc.hce feature constant.
  • MUST support NFC HCE APIs as defined in the Android SDK.

If a device implementation does include an NFC controller chipset capable of HCE for NfcF, and it implements the feature for third-party applications, then it:

  • MUST report the android.hardware.nfc.hcef feature constant.
  • MUST implement the NfcF Card Emulation APIs as defined in the Android SDK.

Additionally, device implementations MAY include reader/writer support for the following MIFARE technologies.

  • MIFARE Classic
  • MIFARE Ultralight
  • NDEF on MIFARE Classic

Note that Android includes APIs for these MIFARE types. If a device implementation supports MIFARE in the reader/writer role, it:

  • MUST implement the corresponding Android APIs as documented by the Android SDK.
  • MUST report the feature com.nxp.mifare from the android.content.pm.PackageManager.hasSystemFeature() method. Note that this is not a standard Android feature and as such does not appear as a constant in the android.content.pm.PackageManager class.
  • MUST NOT implement the corresponding Android APIs nor report the com.nxp.mifare feature unless it also implements general NFC support as described in this section.

If a device implementation does not include NFC hardware, it MUST NOT declare the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method, and MUST implement the Android NFC API as a no-op.

As the classes android.nfc.NdefMessage and android.nfc.NdefRecord represent a protocol-independent data representation format, device implementations MUST implement these APIs even if they do not include support for NFC or declare the android.hardware.nfc feature.

7.4.5. Minimum Network Capability

Device implementations MUST include support for one or more forms of data networking. Specifically, device implementations MUST include support for at least one data standard capable of 200Kbit/sec or greater. Examples of technologies that satisfy this requirement include EDGE, HSPA, EV-DO, 802.11g, Ethernet, Bluetooth PAN, etc.

Device implementations where a physical networking standard (such as Ethernet) is the primary data connection SHOULD also include support for at least one common wireless data standard, such as 802.11 (Wi-Fi).

Devices MAY implement more than one form of data connectivity.

Devices MUST include an IPv6 networking stack and support IPv6 communication using the managed APIs, such as java.net.Socket and java.net.URLConnection , as well as the native APIs, such as AF_INET6 sockets. The required level of IPv6 support depends on the network type, as follows:

  • Devices that support Wi-Fi networks MUST support dual-stack and IPv6-only operation on Wi-Fi.
  • Devices that support Ethernet networks MUST support dual-stack operation on Ethernet.
  • Devices that support cellular data SHOULD support IPv6 operation (IPv6-only and possibly dual-stack) on cellular data.
  • When a device is simultaneously connected to more than one network (eg, Wi-Fi and cellular data), it MUST simultaneously meet these requirements on each network to which it is connected.

IPv6 MUST be enabled by default.

In order to ensure that IPv6 communication is as reliable as IPv4, unicast IPv6 packets sent to the device MUST NOT be dropped, even when the screen is not in an active state. Redundant multicast IPv6 packets, such as repeated identical Router Advertisements, MAY be rate-limited in hardware or firmware if doing so is necessary to save power. In such cases, rate-limiting MUST NOT cause the device to lose IPv6 connectivity on any IPv6-compliant network that uses RA lifetimes of at least 180 seconds.

IPv6 connectivity MUST be maintained in doze mode.

7.4.6.同步設定

Device implementations MUST have the master auto-sync setting on by default so that the method getMasterSyncAutomatically() returns “true”.

7.4.7.資料保護程式

Device implementations with a metered connection are STRONGLY RECOMMENDED to provide the data saver mode.

If a device implementation provides the data saver mode, it:

  • MUST support all the APIs in the ConnectivityManager class as described in the SDK documentation

  • MUST provide a user interface in the settings, allowing users to add applications to or remove applications from the allowlist.

Conversely if a device implementation does not provide the data saver mode, it:

  • MUST return the value RESTRICT_BACKGROUND_STATUS_DISABLED for ConnectivityManager.getRestrictBackgroundStatus()

  • MUST not broadcast ConnectivityManager.ACTION_RESTRICT_BACKGROUND_CHANGED

  • MUST have an activity that handles the Settings.ACTION_IGNORE_BACKGROUND_DATA_RESTRICTIONS_SETTINGS intent but MAY implement it as a no-op.

7.5。相機

Device implementations SHOULD include a rear-facing camera and MAY include a front-facing camera. A rear-facing camera is a camera located on the side of the device opposite the display; that is, it images scenes on the far side of the device, like a traditional camera. A front-facing camera is a camera located on the same side of the device as the display; that is, a camera typically used to image the user, such as for video conferencing and similar applications.

If a device implementation includes at least one camera, it MUST be possible for an application to simultaneously allocate 3 RGBA_8888 bitmaps equal to the size of the images produced by the largest-resolution camera sensor on the device, while camera is open for the purpose of basic preview and still capture.

7.5.1.後置攝像頭

Device implementations SHOULD include a rear-facing camera. If a device implementation includes at least one rear-facing camera, it:

  • MUST report the feature flag android.hardware.camera and android.hardware.camera.any.
  • MUST have a resolution of at least 2 megapixels.
  • SHOULD have either hardware auto-focus or software auto-focus implemented in the camera driver (transparent to application software).
  • MAY have fixed-focus or EDOF (extended depth of field) hardware.
  • MAY include a flash. If the Camera includes a flash, the flash lamp MUST NOT be lit while an android.hardware.Camera.PreviewCallback instance has been registered on a Camera preview surface, unless the application has explicitly enabled the flash by enabling the FLASH_MODE_AUTO or FLASH_MODE_ON attributes of a Camera.Parameters object. Note that this constraint does not apply to the device's built-in system camera application, but only to third-party applications using Camera.PreviewCallback.

7.5.2.前置鏡頭

Device implementations MAY include a front-facing camera. If a device implementation includes at least one front-facing camera, it:

  • MUST report the feature flag android.hardware.camera.any and android.hardware.camera.front.
  • MUST have a resolution of at least VGA (640x480 pixels).
  • MUST NOT use a front-facing camera as the default for the Camera API. The camera API in Android has specific support for front-facing cameras and device implementations MUST NOT configure the API to to treat a front-facing camera as the default rear-facing camera, even if it is the only camera on the device.
  • MAY include features (such as auto-focus, flash, etc.) available to rear-facing cameras as described in section 7.5.1 .
  • MUST horizontally reflect (ie mirror) the stream displayed by an app in a CameraPreview, as follows:
    • If the device implementation is capable of being rotated by user (such as automatically via an accelerometer or manually via user input), the camera preview MUST be mirrored horizontally relative to the device's current orientation.
    • If the current application has explicitly requested that the Camera display be rotated via a call to the android.hardware.Camera.setDisplayOrientation() method, the camera preview MUST be mirrored horizontally relative to the orientation specified by the application.
    • Otherwise, the preview MUST be mirrored along the device's default horizontal axis.
  • MUST mirror the image displayed by the postview in the same manner as the camera preview image stream. If the device implementation does not support postview, this requirement obviously does not apply.
  • MUST NOT mirror the final captured still image or video streams returned to application callbacks or committed to media storage.

7.5.3. External Camera

Device implementations MAY include support for an external camera that is not necessarily always connected. If a device includes support for an external camera, it:

  • MUST declare the platform feature flag android.hardware.camera.external and android.hardware camera.any .
  • MAY support multiple cameras.
  • MUST support USB Video Class (UVC 1.0 or higher) if the external camera connects through the USB port.
  • SHOULD support video compressions such as MJPEG to enable transfer of high-quality unencoded streams (ie raw or independently compressed picture streams).
  • MAY support camera-based video encoding. If supported, a simultaneous unencoded / MJPEG stream (QVGA or greater resolution) MUST be accessible to the device implementation.

7.5.4. Camera API Behavior

Android includes two API packages to access the camera, the newer android.hardware.camera2 API expose lower-level camera control to the app, including efficient zero-copy burst/streaming flows and per-frame controls of exposure, gain, white balance gains, color conversion, denoising, sharpening, and more.

The older API package, android.hardware.Camera, is marked as deprecated in Android 5.0 but as it should still be available for apps to use Android device implementations MUST ensure the continued support of the API as descred in this as thiss in the 。

Device implementations MUST implement the following behaviors for the camera-related APIs, for all available cameras:

  • If an application has never called android.hardware.Camera.Parameters.setPreviewFormat(int), then the device MUST use android.hardware.PixelFormat.YCbCr_420_SP for preview data provided to application callbacks.
  • If an application registers an android.hardware.Camera.PreviewCallback instance and the system calls the onPreviewFrame() method when the preview format is YCbCr_420_SP, the data in the byte[] passed into onPreviewFrame() must further be in the NV21 encoding format. That is, NV21 MUST be the default.
  • For android.hardware.Camera, device implementations MUST support the YV12 format (as denoted by the android.graphics.ImageFormat.YV12 constant) for camera previews for both front- and rear-facing cameras. (The hardware video encoder and camera may use any native pixel format, but the device implementation MUST support conversion to YV12.)
  • For android.hardware.camera2, device implementations must support the android.hardware.ImageFormat.YUV_420_888 and android.hardware.ImageFormat.JPEG formats as outputs through the android.media.ImageReader API.

Device implementations MUST still implement the full Camera API included in the Android SDK documentation, regardless of whether the device includes hardware autofocus or other capabilities. For instance, cameras that lack autofocus MUST still call any registered android.hardware.Camera.AutoFocusCallback instances (even though this has no relevance to a non-autofocus camera.) Note that this does apply to front-facing cameras; for instance, even though most front-facing cameras do not support autofocus, the API callbacks must still be “faked” as described.

Device implementations MUST recognize and honor each parameter name defined as a constant on the android.hardware.Camera.Parameters class, if the underlying hardware supports the feature. If the device hardware does not support a feature, the API must behave as documented. Conversely, device implementations MUST NOT honor or recognize string constants passed to the android.hardware.Camera.setParameters() method other than those documented as constants on the android.hardware.Camera.Parameters. That is, device implementations MUST support all standard Camera parameters if the hardware allows, and MUST NOT support custom Camera parameter types. For instance, device implementations that support image capture using high dynamic range (HDR) imaging techniques MUST support camera parameter Camera.SCENE_MODE_HDR.

Because not all device implementations can fully support all the features of the android.hardware.camera2 API, device implementations MUST report the proper level of support with the android.info.supportedHardwareLevel property as level of support with the android.info.supportedHardwareLevel property 是 as descramef in fate SDdrowate Aprit. 。

Device implementations MUST also declare its Individual camera capabilities of android.hardware.camera2 via the android.request.availableCapabilities property and declare the appropriate feature flags ; a device must define the feature flag if any of its attached camera devices supports the feature.

Device implementations MUST broadcast the Camera.ACTION_NEW_PICTURE intent whenever a new picture is taken by the camera and the entry of the picture has been added to the media store.

Device implementations MUST broadcast the Camera.ACTION_NEW_VIDEO intent whenever a new video is recorded by the camera and the entry of the picture has been added to the media store.

7.5.5。 Camera Orientation

Both front- and rear-facing cameras, if present, MUST be oriented so that the long dimension of the camera aligns with the screen's long dimension. That is, when the device is held in the landscape orientation, cameras MUST capture images in the landscape orientation. This applies regardless of the device's natural orientation; that is, it applies to landscape-primary devices as well as portrait-primary devices.

7.6。記憶體和儲存

7.6.1. Minimum Memory and Storage

Android Television devices MUST have at least 4GB of non-volatile storage available for application private data.

The memory available to the kernel and userspace on device implementations MUST be at least equal or larger than the minimum values specified by the following table. (See section 7.1.1 for screen size and density definitions.)

Density and screen size 32-bit device 64-bit device
Android Watch devices (due to smaller screens) 416MB不適用
  • 280dpi or lower on small/normal screens
  • mdpi or lower on large screens
  • ldpi or lower on extra large screens
 512MB 816MB
  • xhdpi or higher on small/normal screens
  • hdpi or higher on large screens
  • mdpi or higher on extra large screens
 608MB 944MB
  • 400dpi or higher on small/normal screens
  • xhdpi or higher on large screens
  • tvdpi or higher on extra large screens
 896MB 1280MB
  • 560dpi or higher on small/normal screens
  • 400dpi or higher on large screens
  • xhdpi or higher on extra large screens
 1344MB 1824MB

The minimum memory values MUST be in addition to any memory space already dedicated to hardware components such as radio, video, and so on that is not under the kernel's control.

Device implementations with less than 512MB of memory available to the kernel and userspace, unless an Android Watch, MUST return the value "true" for ActivityManager.isLowRamDevice().

Android Television devices MUST have at least 4GB and other device implementations MUST have at least 3GB of non-volatile storage available for application private data. That is, the /data partition MUST be at least 4GB for Android Television devices and at least 3GB for other device implementations. Device implementations that run Android are STRONGLY RECOMMENDED to have at least 4GB of non-volatile storage for application private data so they will be able to upgrade to the future platform releases.

The Android APIs include a Download Manager that applications MAY use to download data files. The device implementation of the Download Manager MUST be capable of downloading individual files of at least 100MB in size to the default “cache” location.

7.6.2. Application Shared Storage

Device implementations MUST offer shared storage for applications also often referred as “shared external storage”.

Device implementations MUST be configured with shared storage mounted by default, “out of the box”. If the shared storage is not mounted on the Linuxpath /sdcard, then the device MUST include a Linux symbolic link from /sdcard to the actual mount point.

Device implementations MAY have hardware for user-accessible removable storage, such as a Secure Digital (SD) card slot. If this slot is used to satisfy the shared storage requirement, the device implementation:

  • MUST implement a toast or pop-up user interface warning the user when there is no SD card.
  • MUST include a FAT-formatted SD card 1GB in size or larger OR show on the box and other material available at time of purchase that the SD card has to be separately purchased.
  • MUST mount the SD card by default.

Alternatively, device implementations MAY allocate internal (non-removable) storage as shared storage for apps as included in the upstream Android Open Source Project; device implementations SHOULD use this configuration and software implementation. If a device implementation uses internal (non-removable) storage to satisfy the shared storage requirement, while that storage MAY share space with the application private data, it MUST be at least 1GB in size and mounted on /sdcard (or /sdcard MUST be a symbolic link to the physical location if it is mounted elsewhere).

Device implementations MUST enforce as documented the android.permission.WRITE_EXTERNAL_STORAGE permission on this shared storage. Shared storage MUST otherwise be writable by any application that obtains that permission.

Device implementations that include multiple shared storage paths (such as both an SD card slot and shared internal storage) MUST allow only pre-installed & privileged Android applications with the WRITE_EXTERNAL_STORAGE permission to write to the secondary external storage, except when writing to their package-specific directories or within the URI returned by firing the ACTION_OPEN_DOCUMENT_TREE intent.

However, device implementations SHOULD expose content from both storage paths transparently through Android's media scanner service and android.provider.MediaStore.

Regardless of the form of shared storage used, if the device implementation has a USB port with USB peripheral mode support, it MUST provide some mechanism to access the contents of shared storage from a host computer. Device implementations MAY use USB mass storage, but SHOULD use Media Transfer Protocol to satisfy this requirement. If the device implementation supports Media Transfer Protocol, it:

  • SHOULD be compatible with the reference Android MTP host, Android File Transfer .
  • SHOULD report a USB device class of 0x00.
  • SHOULD report a USB interface name of 'MTP'.

7.6.3. Adoptable Storage

Device implementations are STRONGLY RECOMMENDED to implement adoptable storage if the removable storage device port is in a long-term stable location, such as within the battery compartment or other protective cover.

Device implementations such as a television, MAY enable adoption through USB ports as the device is expected to be static and not mobile. But for other device implementations that are mobile in nature, it is STRONGLY RECOMMENDED to implement the adoptable storage in a long-term stable location, since accidentally disconnecting them can cause data loss/corruption.

7.7. USB

Device implementations SHOULD support USB peripheral mode and SHOULD support USB host mode.

7.7.1. USB peripheral mode

If a device implementation includes a USB port supporting peripheral mode:

  • The port MUST be connectable to a USB host that has a standard type-A or type-C USB port.
  • The port SHOULD use micro-B, micro-AB or Type-C USB form factor. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to the future platform releases.
  • The port SHOULD be located on the bottom of the device (according to natural orientation) or enable software screen rotation for all apps (including home screen), so that the display draws correctly when the device is oriented with the port at bottom. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to future platform releases.
  • It MUST allow a USB host connected with the Android device to access the contents of the shared storage volume using either USB mass storage or Media Transfer Protocol.
  • It SHOULD implement the Android Open Accessory (AOA) API and specification as documented in the Android SDK documentation, and if it is an Android Handheld device it MUST implement the AOA API. Device implementations implementing the AOA specification:
    • MUST declare support for the hardware feature android.hardware.usb.accessory .
    • MUST implement the USB audio class as documented in the Android SDK documentation.
    • The USB mass storage class MUST include the string "android" at the end of the interface description iInterface string of the USB mass storage
  • It SHOULD implement support to draw 1.5 A current during HS chirp and traffic as specified in the USB Battery Charging specification, revision 1.2 . Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to the future platform releases.
  • Type-C devices MUST detect 1.5A and 3.0A chargers per the Type-C resistor standard and it must detect changes in the advertisement.
  • Type-C devices also supporting USB host mode are STRONGLY RECOMMENDED to support Power Delivery for data and power role swapping.
  • Type-C devices SHOULD support Power Delivery for high-voltage charging and support for Alternate Modes such as display out.
  • The value of iSerialNumber in USB standard device descriptor MUST be equal to the value of android.os.Build.SERIAL.
  • Type-C devices are STRONGLY RECOMMENDED to not support proprietary charging methods that modify Vbus voltage beyond default levels, or alter sink/source roles as such may result in interoperability issues with the chargers or devices that support the standard USB Power Delivery methods. While this is called out as "STRONGLY RECOMMENDED", in future Android versions we might REQUIRE all type-C devices to support full interoperability with standard type-C chargers.

7.7.2. USB host mode

If a device implementation includes a USB port supporting host mode, it:

  • SHOULD use a type-C USB port, if the device implementation supports USB 3.1.
  • MAY use a non-standard port form factor, but if so MUST ship with a cable or cables adapting the port to a standard type-A or type-C USB port.
  • MAY use a micro-AB USB port, but if so SHOULD ship with a cable or cables adapting the port to a standard type-A or type-C USB port.
  • is STRONGLY RECOMMENDED to implement the USB audio class as documented in the Android SDK documentation.
  • MUST implement the Android USB host API as documented in the Android SDK, and MUST declare support for the hardware feature android.hardware.usb.host .
  • SHOULD support device charging while in host mode; advertising a source current of at least 1.5A as specified in the Termination Parameters section of the [USB Type-C Cable and Connector Specification Revision 1.2] (http://www.usb.org/developers/docs/usb_31_021517.zip) for USB Type-C connectors or using Charging Downstream Port(CDP) output current range as specified in the USB Battery Charging specifications, revision 1.2 for Micro-AB connectors.
  • USB Type-C devices are STRONGLY RECOMMENDED to support DisplayPort, SHOULD support USB SuperSpeed Data Rates, and are STRONGLY RECOMMENDED to support Power Delivery for data and power role swapping.
  • Devices with any type-A or type-AB ports MUST NOT ship with an adapter converting from this port to a type-C receptacle.
  • MUST recognize any remotely connected MTP (Media Transfer Protocol) devices and make their contents accessible through the ACTION_GET_CONTENT , ACTION_OPEN_DOCUMENT , and ACTION_CREATE_DOCUMENT intents, if the Storage Access Framework (SAF) is supported.
  • MUST, if using a Type-C USB port and including support for peripheral mode, implement Dual Role Port functionality as defined by the USB Type-C specification (section 4.5.1.3.3).
  • SHOULD, if the Dual Role Port functionality is supported, implement the Try.* model that is most appropriate for the device form factor. For example a handheld device SHOULD implement the Try.SNK model.

7.8。聲音的

7.8.1.麥克風

Android Handheld, Watch, and Automotive implementations MUST include a microphone.

Device implementations MAY omit a microphone. However, if a device implementation omits a microphone, it MUST NOT report the android.hardware.microphone feature constant, and MUST implement the audio recording API at least as no-ops, per section 7 . Conversely, device implementations that do possess a microphone:

  • MUST report the android.hardware.microphone feature constant.
  • MUST meet the audio recording requirements in section 5.4 .
  • MUST meet the audio latency requirements in section 5.6 .
  • STRONGLY RECOMMENDED to support near-ultrasound recording as described in section 7.8.3 .

7.8.2.音訊輸出

Android Watch devices MAY include an audio output.

Device implementations including a speaker or with an audio/multimedia output port for an audio output peripheral as a headset or an external speaker:

  • MUST report the android.hardware.audio.output feature constant.
  • MUST meet the audio playback requirements in section 5.5 .
  • MUST meet the audio latency requirements in section 5.6 .
  • STRONGLY RECOMMENDED to support near-ultrasound playback as described in section 7.8.3 .

Conversely, if a device implementation does not include a speaker or audio output port, it MUST NOT report the android.hardware.audio output feature, and MUST implement the Audio Output related APIs as no-ops at least.

Android Watch device implementation MAY but SHOULD NOT have audio output, but other types of Android device implementations MUST have an audio output and declare android.hardware.audio.output.

7.8.2.1. Analog Audio Ports

In order to be compatible with the headsets and other audio accessories using the 3.5mm audio plug across the Android ecosystem, if a device implementation includes one or more analog audio ports, at least one of the audio port(s) SHOULD be a 4 conductor 3.5mm audio jack. If a device implementation has a 4 conductor 3.5mm audio jack, it:

  • MUST support audio playback to stereo headphones and stereo headsets with a microphone, and SHOULD support audio recording from stereo headsets with a microphone.
  • MUST support TRRS audio plugs with the CTIA pin-out order, and SHOULD support audio plugs with the OMTP pin-out order.
  • MUST support the detection of microphone on the plugged in audio accessory, if the device implementation supports a microphone, and broadcast the android.intent.action.HEADSET_PLUG with the extra value microphone set as 1.
  • MUST support the detection and mapping to the keycodes for the following 3 ranges of equivalent impedance between the microphone and ground conductors on the audio plug:
    • 70 ohm or less : KEYCODE_HEADSETHOOK
    • 210-290 Ohm : KEYCODE_VOLUME_UP
    • 360-680 Ohm : KEYCODE_VOLUME_DOWN
  • STRONGLY RECOMMENDED to detect and map to the keycode for the following range of equivalent impedance between the microphone and ground conductors on the audio plug:
    • 110-180 Ohm: KEYCODE_VOICE_ASSIST
  • MUST trigger ACTION_HEADSET_PLUG upon a plug insert, but only after all contacts on plug are touching their relevant segments on the jack.
  • MUST be capable of driving at least 150mV ± 10% of output voltage on a 32 Ohm speaker impedance.
  • MUST have a microphone bias voltage between 1.8V ~ 2.9V.

7.8.3。 Near-Ultrasound

Near-Ultrasound audio is the 18.5 kHz to 20 kHz band. Device implementations MUST correctly report the support of near-ultrasound audio capability via the AudioManager.getProperty API as follows:

  • If PROPERTY_SUPPORT_MIC_NEAR_ULTRASOUND is "true", then the following requirements must be met by the VOICE_RECOGNITION and UNPROCESSED audio sources:
    • The microphone's mean power response in the 18.5 kHz to 20 kHz band MUST be no more than 15 dB below the response at 2 kHz.
    • The microphone's unweighted signal to noise ratio over 18.5 kHz to 20 kHz for a 19 kHz tone at -26 dBFS MUST be no lower than 50 dB.
  • If PROPERTY_SUPPORT_SPEAKER_NEAR_ULTRASOUND is "true", then the speaker's mean response in 18.5 kHz - 20 kHz MUST be no lower than 40 dB below the response at 2 kHz.

7.9。虛擬實境

Android includes APIs and facilities to build "Virtual Reality" (VR) applications including high quality mobile VR experiences. Device implementations MUST properly implement these APIs and behaviors, as detailed in this section.

7.9.1. Virtual Reality Mode

Android handheld device implementations that support a mode for VR applications that handles stereoscopic rendering of notifications and disable monocular system UI components while a VR application has user focus MUST declare android.software.vr.mode feature. Devices declaring this feature MUST include an application implementing android.service.vr.VrListenerService that can be enabled by VR applications via android.app.Activity#setVrModeEnabled .

7.9.2. Virtual Reality High Performance

Android handheld device implementations MUST identify the support of high performance virtual reality for longer user periods through the android.hardware.vr.high_performance feature flag and meet the following requirements.

  • Device implementations MUST have at least 2 physical cores.
  • Device implementations MUST declare android.software.vr.mode feature.
  • Device implementations MAY provide an exclusive core to the foreground application and MAY support the Process.getExclusiveCores API to return the numbers of the cpu cores that are exclusive to the top foreground application. If exclusive core is supported then the core MUST not allow any other userspace processes to run on it (except device drivers used by the application), but MAY allow some kernel processes to run as necessary.
  • Device implementations MUST support sustained performance mode.
  • Device implementations MUST support OpenGL ES 3.2.
  • Device implementations MUST support Vulkan Hardware Level 0 and SHOULD support Vulkan Hardware Level 1.
  • Device implementations MUST implement EGL_KHR_mutable_render_buffer and EGL_ANDROID_front_buffer_auto_refresh, EGL_ANDROID_create_native_client_buffer, EGL_KHR_fence_sync and EGL_KHR_wait_sync so that they may be used for Shared Buffer Mode, and expose the extensions in the list of available EGL extensions.
  • The GPU and display MUST be able to synchronize access to the shared front buffer such that alternating-eye rendering of VR content at 60fps with two render contexts will be displayed with no visible tearing artifacts.
  • Device implementations MUST implement EGL_IMG_context_priority, and expose the extension in the list of available EGL extensions.
  • Device implementations MUST implement GL_EXT_multisampled_render_to_texture, GL_OVR_multiview, GL_OVR_multiview2 and GL_OVR_multiview_multisampled_render_to_texture, and expose the extensions in the list of available GL extensions.
  • Device implementations MUST implement EGL_EXT_protected_content and GL_EXT_protected_textures so that it may be used for Secure Texture Video Playback, and expose the extensions in the list of available EGL and GL extensions.
  • Device implementations MUST support H.264 decoding at least 3840x2160@30fps-40Mbps (equivalent to 4 instances of 1920x1080@30fps-10Mbps or 2 instances of 1920x1080@60fps-20Mbps).
  • Device implementations MUST support HEVC and VP9, MUST be capable to decode at least 1920x1080@30fps-10Mbps and SHOULD be capable to decode 3840x2160@30fps-20Mbps (equivalent to 4 instances of 1920x1080@30fps-5Mbps).
  • The device implementations are STRONGLY RECOMMENDED to support android.hardware.sensor.hifi_sensors feature and MUST meet the gyroscope, accelerometer, and magnetometer related requirements for android.hardware.hifi_sensors.
  • Device implementations MUST support HardwarePropertiesManager.getDeviceTemperatures API and return accurate values for skin temperature.
  • The device implementation MUST have an embedded screen, and its resolution MUST be at least be FullHD(1080p) and STRONGLY RECOMMENDED TO BE be QuadHD (1440p) or higher.
  • The display MUST measure between 4.7" and 6" diagonal.
  • The display MUST update at least 60 Hz while in VR Mode.
  • The display latency on Gray-to-Gray, White-to-Black, and Black-to-White switching time MUST be ≤ 3 ms.
  • The display MUST support a low-persistence mode with ≤5 ms persistence,persistence being defined as the amount of time for which a pixel is emitting light.
  • Device implementations MUST support Bluetooth 4.2 and Bluetooth LE Data Length Extension section 7.4.3 .

8. Performance and Power

Some minimum performance and power criteria are critical to the user experience and impact the baseline assumptions developers would have when developing an app. Android Watch devices SHOULD and other type of device implementations MUST meet the following criteria.

8.1. User Experience Consistency

Device implementations MUST provide a smooth user interface by ensuring a consistent frame rate and response times for applications and games. Device implementations MUST meet the following requirements:

  • Consistent frame latency . Inconsistent frame latency or a delay to render frames MUST NOT happen more often than 5 frames in a second, and SHOULD be below 1 frames in a second.
  • User interface latency . Device implementations MUST ensure low latency user experience by scrolling a list of 10K list entries as defined by the Android Compatibility Test Suite (CTS) in less than 36 secs.
  • 任務切換。 When multiple applications have been launched, re-launching an already-running application after it has been launched MUST take less than 1 second.

8.2. File I/O Access Performance

Device implementations MUST ensure internal storage file access performance consistency for read and write operations.

  • Sequential write . Device implementations MUST ensure a sequential write performance of at least 5MB/s for a 256MB file using 10MB write buffer.
  • Random write . Device implementations MUST ensure a random write performance of at least 0.5MB/s for a 256MB file using 4KB write buffer.
  • Sequential read . Device implementations MUST ensure a sequential read performance of at least 15MB/s for a 256MB file using 10MB write buffer.
  • Random read . Device implementations MUST ensure a random read performance of at least 3.5MB/s for a 256MB file using 4KB write buffer.

8.3. Power-Saving Modes

Android 6.0 introduced App Standby and Doze power-saving modes to optimize battery usage. All Apps exempted from these modes MUST be made visible to the end user. Further, the triggering, maintenance, wakeup algorithms and the use of global system settings of these power-saving modes MUST not deviate from the Android Open Source Project.

In addition to the power-saving modes, Android device implementations MAY implement any or all of the 4 sleeping power states as defined by the Advanced Configuration and Power Interface (ACPI), but if it implements S3 and S4 power states, it can only enter these states when closing a lid that is physically part of the device.

8.4. Power Consumption Accounting

A more accurate accounting and reporting of the power consumption provides the app developer both the incentives and the tools to optimize the power usage pattern of the application. Therefore, device implementations:

  • MUST be able to track hardware component power usage and attribute that power usage to specific applications. Specifically, implementations:
    • MUST provide a per-component power profile that defines the current consumption value for each hardware component and the approximate battery drain caused by the components over time as documented in the Android Open Source Project site.
    • MUST report all power consumption values in milliampere hours (mAh).
    • SHOULD be attributed to the hardware component itself if unable to attribute hardware component power usage to an application.
    • MUST report CPU power consumption per each process's UID. The Android Open Source Project meets the requirement through the uid_cputime kernel module implementation.
  • MUST make this power usage available via the adb shell dumpsys batterystats shell command to the app developer.
  • MUST honor the android.intent.action.POWER_USAGE_SUMMARY intent and display a settings menu that shows this power usage.

8.5。一致的性能

Performance can fluctuate dramatically for high-performance long-running apps, either because of the other apps running in the background or the CPU throttling due to temperature limits. Android includes programmatic interfaces so that when the device is capable, the top foreground application can request that the system optimize the allocation of the resources to address such fluctuations.

Device implementations SHOULD support Sustained Performance Mode which can provide the top foreground application a consistent level of performance for a prolonged amount of time when requested through the Window.setSustainedPerformanceMode() API method. A Device implementation MUST report the support of Sustained Performance Mode accurately through the PowerManager.isSustainedPerformanceModeSupported() API method.

Device implementations with two or more CPU cores SHOULD provide at least one exclusive core that can be reserved by the top foreground application. If provided, implementations MUST meet the following requirements:

  • Implementations MUST report through the Process.getExclusiveCores() API method the id numbers of the exclusive cores that can be reserved by the top foreground application.
  • Device implementations MUST not allow any user space processes except the device drivers used by the application to run on the exclusive cores, but MAY allow some kernel processes to run as necessary.

If a device implementation does not support an exclusive core, it MUST return an empty list through the Process.getExclusiveCores() API method.

9. Security Model Compatibility

Device implementations MUST implement a security model consistent with the Android platform security model as defined in Security and Permissions reference document in the APIs in the Android developer documentation. Device implementations MUST support installation of self-signed applications without requiring any additional permissions/certificates from any third parties/authorities. Specifically, compatible devices MUST support the security mechanisms described in the follow subsections.

9.1.權限

Device implementations MUST support the Android permissions model as defined in the Android developer documentation. Specifically, implementations MUST enforce each permission defined as described in the SDK documentation; no permissions may be omitted, altered, or ignored. Implementations MAY add additional permissions, provided the new permission ID strings are not in the android.* namespace.

Permissions with a protectionLevel of 'PROTECTION_FLAG_PRIVILEGED' MUST only be granted to apps preloaded in the allowlisted privileged path(s) of the system image, such as the system/priv-app path in the AOSP implementation.

Permissions with a protection level of dangerous are runtime permissions. Applications with targetSdkVersion > 22 request them at runtime. Device implementations:

  • MUST show a dedicated interface for the user to decide whether to grant the requested runtime permissions and also provide an interface for the user to manage runtime permissions.
  • MUST have one and only one implementation of both user interfaces.
  • MUST NOT grant any runtime permissions to preinstalled apps unless:
    • the user's consent can be obtained before the application uses it
    • the runtime permissions are associated with an intent pattern for which the preinstalled application is set as the default handler

9.2. UID and Process Isolation

Device implementations MUST support the Android application sandbox model, in which each application runs as a unique Unixstyle UID and in a separate process. Device implementations MUST support running multiple applications as the same Linux user ID, provided that the applications are properly signed and constructed, as defined in the Security and Permissions reference .

9.3. Filesystem Permissions

Device implementations MUST support the Android file access permissions model as defined in the Security and Permissions reference .

9.4. Alternate Execution Environments

Device implementations MAY include runtime environments that execute applications using some other software or technology than the Dalvik Executable Format or native code. However, such alternate execution environments MUST NOT compromise the Android security model or the security of installed Android applications, as described in this section.

Alternate runtimes MUST themselves be Android applications, and abide by the standard Android security model, as described elsewhere in section 9 .

Alternate runtimes MUST NOT be granted access to resources protected by permissions not requested in the runtime's AndroidManifest.xml file via the <uses-permission> mechanism.

Alternate runtimes MUST NOT permit applications to make use of features protected by Android permissions restricted to system applications.

Alternate runtimes MUST abide by the Android sandbox model. Specifically, alternate runtimes:

  • SHOULD install apps via the PackageManager into separate Android sandboxes (Linux user IDs, etc.).
  • MAY provide a single Android sandbox shared by all applications using the alternate runtime.
  • Installed applications using an alternate runtime MUST NOT reuse the sandbox of any other app installed on the device, except through the standard Android mechanisms of shared user ID and signing certificate.
  • MUST NOT launch with, grant, or be granted access to the sandboxes corresponding to other Android applications.
  • MUST NOT be launched with, be granted, or grant to other applications any privileges of the superuser (root), or of any other user ID.

The .apk files of alternate runtimes MAY be included in the system image of a device implementation, but MUST be signed with a key distinct from the key used to sign other applications included with the device implementation.

When installing applications, alternate runtimes MUST obtain user consent for the Android permissions used by the application. If an application needs to make use of a device resource for which there is a corresponding Android permission (such as Camera, GPS, etc.), the alternate runtime MUST inform the user that the application will be able to access that resource. If the runtime environment does not record application capabilities in this manner, the runtime environment MUST list all permissions held by the runtime itself when installing any application using that runtime.

9.5。 Multi-User Support

This feature is optional for all device types.

Android includes support for multiple users and provides support for full user isolation. Device implementations MAY enable multiple users, but when enabled MUST meet the following requirements related to multi-user support :

  • Android Automotive device implementations with multi-user support enabled MUST include a guest account that allows all functions provided by the vehicle system without requiring a user to log in.
  • Device implementations that do not declare the android.hardware.telephony feature flag MUST support restricted profiles, a feature that allows device owners to manage additional users and their capabilities on the device. With restricted profiles, device owners can quickly set up separate environments for additional users to work in, with the ability to manage finer-grained restrictions in the apps that are available in those environments.
  • Conversely device implementations that declare the android.hardware.telephony feature flag MUST NOT support restricted profiles but MUST align with the AOSP implementation of controls to enable /disable other users from accessing the voice calls and SMS.
  • Device implementations MUST, for each user, implement a security model consistent with the Android platform security model as defined in Security and Permissions reference document in the APIs.
  • Each user instance on an Android device MUST have separate and isolated external storage directories. Device implementations MAY store multiple users' data on the same volume or filesystem. However, the device implementation MUST ensure that applications owned by and running on behalf a given user cannot list, read, or write to data owned by any other user. Note that removable media, such as SD card slots, can allow one user to access another's data by means of a host PC. For this reason, device implementations that use removable media for the external storage APIs MUST encrypt the contents of the SD card if multiuser is enabled using a key stored only on non-removable media accessible only to the system. As this will make the media unreadable by a host PC, device implementations will be required to switch to MTP or a similar system to provide host PCs with access to the current user's data. Accordingly, device implementations MAY but SHOULD NOT enable multi-user if they use removable media for primary external storage.

9.6. Premium SMS Warning

Android includes support for warning users of any outgoing premium SMS message . Premium SMS messages are text messages sent to a service registered with a carrier that may incur a charge to the user. Device implementations that declare support for android.hardware.telephony MUST warn users before sending a SMS message to numbers identified by regular expressions defined in /data/misc/sms/codes.xml file in the device. The upstream Android Open Source Project provides an implementation that satisfies this requirement.

9.7. Kernel Security Features

The Android Sandbox includes features that use the Security-Enhanced Linux (SELinux) mandatory access control (MAC) system, seccomp sandboxing, and other security features in the Linux kernel. SELinux or any other security features implemented below the Android framework:

  • MUST maintain compatibility with existing applications.
  • MUST NOT have a visible user interface when a security violation is detected and successfully blocked, but MAY have a visible user interface when an unblocked security violation occurs resulting in a successful exploit.
  • SHOULD NOT be user or developer configurable.

If any API for configuration of policy is exposed to an application that can affect another application (such as a Device Administration API), the API MUST NOT allow configurations that break compatibility.

Devices MUST implement SELinux or, if using a kernel other than Linux, an equivalent mandatory access control system. Devices MUST also meet the following requirements, which are satisfied by the reference implementation in the upstream Android Open Source Project.

Device implementations:

  • MUST set SELinux to global enforcing mode.
  • MUST configure all domains in enforcing mode. No permissive mode domains are allowed, including domains specific to a device/vendor.
  • MUST NOT modify, omit, or replace the neverallow rules present within the system/sepolicy folder provided in the upstream Android Open Source Project (AOSP) and the policy MUST compile with all neverallow rules present, for both AOSP SELinux domains as well as device/vendor specific domains.
  • MUST split the media framework into multiple processes so that it is possible to more narrowly grant access for each process as described in the Android Open Source Project site.

Device implementations SHOULD retain the default SELinux policy provided in the system/sepolicy folder of the upstream Android Open Source Project and only further add to this policy for their own device-specific configuration. Device implementations MUST be compatible with the upstream Android Open Source Project.

Devices MUST implement a kernel application sandboxing mechanism which allows filtering of system calls using a configurable policy from multithreaded programs. The upstream Android Open Source Project meets this requirement through enabling the seccomp-BPF with threadgroup synchronization (TSYNC) as described in the Kernel Configuration section of source.android.com .

9.8.隱私

If the device implements functionality in the system that captures the contents displayed on the screen and/or records the audio stream played on the device, it MUST continuously notify the user whenever this functionality is enabled and actively capturing/recording.

If a device implementation has a mechanism that routes network data traffic through a proxy server or VPN gateway by default (for example, preloading a VPN service with android.permission.CONTROL_VPN granted), the device implementation MUST ask for the user's consent before enabling that mechanism, unless that VPN is enabled by the Device Policy Controller via the DevicePolicyManager.setAlwaysOnVpnPackage() , in which case the user does not need to provide a separate consent, but MUST only be notified.

Device implementations MUST ship with an empty user-added Certificate Authority (CA) store, and MUST preinstall the same root certificates for the system-trusted CA store as provided in the upstream Android Open Source Project.

When devices are routed through a VPN, or a user root CA is installed, the implementation MUST display a warning indicating the network traffic may be monitored to the user.

If a device implementation has a USB port with USB peripheral mode support, it MUST present a user interface asking for the user's consent before allowing access to the contents of the shared storage over the USB port.

9.9. Data Storage Encryption

Optional for Android device implementations without a secure lock screen.

If the device implementation supports a secure lock screen as described in section 9.11.1, then the device MUST support data storage encryption of the application private data (/data partition), as well as the application shared storage partition (/sdcard partition) if it is a permanent, non-removable part of the device.

For device implementations supporting data storage encryption and with Advanced Encryption Standard (AES) crypto performance above 50MiB/sec, the data storage encryption MUST be enabled by default at the time the user has completed the out-of-box setup experience. If a device implementation is already launched on an earlier Android version with encryption disabled by default, such a device cannot meet the requirement through a system software update and thus MAY be exempted.

Device implementations SHOULD meet the above data storage encryption requirement via implementing File Based Encryption (FBE).

9.9.1. Direct Boot

All devices MUST implement the Direct Boot mode APIs even if they do not support Storage Encryption. In particular, the LOCKED_BOOT_COMPLETED and ACTION_USER_UNLOCKED Intents must still be broadcast to signal Direct Boot aware applications that Device Encrypted (DE) and Credential Encrypted (CE) storage locations are available for user.

9.9.2. File Based Encryption

Device implementations supporting FBE:

  • MUST boot up without challenging the user for credentials and allow Direct Boot aware apps to access to the Device Encrypted (DE) storage after the LOCKED_BOOT_COMPLETED message is broadcasted.
  • MUST only allow access to Credential Encrypted (CE) storage after the user has unlocked the device by supplying their credentials (eg. passcode, pin, pattern or fingerprint) and the ACTION_USER_UNLOCKED message is broadcasted. Device implementations MUST NOT offer any method to unlock the CE protected storage without the user supplied credentials.
  • MUST support Verified Boot and ensure that DE keys are cryptographically bound to the device's hardware root of trust.
  • MUST support encrypting file contents using AES with a key length of 256-bits in XTS mode.
  • MUST support encrypting file name using AES with a key length of 256-bits in CBC-CTS mode.
  • MAY support alternative ciphers, key lengths and modes for file content and file name encryption, but MUST use the mandatorily supported ciphers, key lengths and modes by default.
  • SHOULD make preloaded essential apps (eg Alarm, Phone, Messenger) Direct Boot aware.

The keys protecting CE and DE storage areas:

  • MUST be cryptographically bound to a hardware-backed Keystore. CE keys must be bound to a user's lock screen credentials. If the user has specified no lock screen credentials then the CE keys MUST be bound to a default passcode.
  • MUST be unique and distinct, in other words no user's CE or DE key may match any other user's CE or DE keys.

The upstream Android Open Source project provides a preferred implementation of this feature based on the Linux kernel ext4 encryption feature.

9.9.3. Full Disk Encryption

Device implementations supporting full disk encryption (FDE). MUST use AES with a key of 128-bits (or greater) and a mode designed for storage (for example, AES-XTS, AES-CBC-ESSIV). The encryption key MUST NOT be written to storage at any time without being encrypted. The user MUST be provided with the possibility to AES encrypt the encryption key, except when it is in active use, with the lock screen credentials stretched using a slow stretching algorithm (eg PBKDF2 or scrypt). If the user has not specified a lock screen credentials or has disabled use of the passcode for encryption, the system SHOULD use a default passcode to wrap the encryption key. If the device provides a hardware-backed keystore, the password stretching algorithm MUST be cryptographically bound to that keystore. The encryption key MUST NOT be sent off the device (even when wrapped with the user passcode and/or hardware bound key). The upstream Android Open Source project provides a preferred implementation of this feature based on the Linux kernel feature dm-crypt.

9.10。 Device Integrity

The following requirements ensures there is transparency to the status of the device integrity.

Device implementations MUST correctly report through the System API method PersistentDataBlockManager.getFlashLockState() whether their bootloader state permits flashing of the system image. The FLASH_LOCK_UNKNOWN state is reserved for device implementations upgrading from an earlier version of Android where this new system API method did not exist.

Verified boot is a feature that guarantees the integrity of the device software. If a device implementation supports the feature, it MUST:

  • Declare the platform feature flag android.software.verified_boot.
  • Perform verification on every boot sequence.
  • Start verification from an immutable hardware key that is the root of trust and go all the way up to the system partition.
  • Implement each stage of verification to check the integrity and authenticity of all the bytes in the next stage before executing the code in the next stage.
  • Use verification algorithms as strong as current recommendations from NIST for hashing algorithms (SHA-256) and public key sizes (RSA-2048).
  • MUST NOT allow boot to complete when system verification fails, unless the user consents to attempt booting anyway, in which case the data from any non-verified storage blocks MUST not be used.
  • MUST NOT allow verified partitions on the device to be modified unless the user has explicitly unlocked the boot loader.

The upstream Android Open Source Project provides a preferred implementation of this feature based on the Linux kernel feature dm-verity.

Starting from Android 6.0, device implementations with Advanced Encryption Standard (AES) crypto performance above 50 MiB/seconds MUST support verified boot for device integrity.

If a device implementation is already launched without supporting verified boot on an earlier version of Android, such a device can not add support for this feature with a system software update and thus are exempted from the requirement.

9.11。 Keys and Credentials

The Android Keystore System allows app developers to store cryptographic keys in a container and use them in cryptographic operations through the KeyChain API or the Keystore API .

All Android device implementations MUST meet the following requirements:

  • SHOULD not limit the number of keys that can be generated, and MUST at least allow more than 8,192 keys to be imported.
  • The lock screen authentication MUST rate limit attempts and MUST have an exponential backoff algorithm. Beyond 150 failed attempts, the delay MUST be at least 24 hours per attempt.
  • When the device implementation supports a secure lock screen it MUST back up the keystore implementation with secure hardware and meet following requirements:
    • MUST have implementations of RSA, AES, ECDSA and HMAC cryptographic algorithms and MD5, SHA1, and SHA-2 family hash functions to properly support the Android Keystore system's supported algorithms in an area that is kerbrea that is thekly sional the emr. 。 Secure isolation MUST block all potential mechanisms by which kernel or userspace code might access the internal state of the isolated environment, including DMA. The upstream Android Open Source Project (AOSP) meets this requirement by using the Trusty implementation, but another ARM TrustZone-based solution or a third-party reviewed secure implementation of a proper hypervisor-based isolation are alternative options.
    • MUST perform the lock screen authentication in the isolated execution environment and only when successful, allow the authentication-bound keys to be used. The upstream Android Open Source Project provides the Gatekeeper Hardware Abstraction Layer (HAL) and Trusty, which can be used to satisfy this requirement.

Note that if a device implementation is already launched on an earlier Android version, such a device is exempted from the requirement to have a hardware-backed keystore, unless it declares the android.hardware.fingerprint feature which requires a hardware-backed keystore.

9.11.1. Secure Lock Screen

Device implementations MAY add or modify the authentication methods to unlock the lock screen, but MUST still meet the following requirements:

  • The authentication method, if based on a known secret, MUST NOT be treated as a secure lock screen unless it meets all following requirements:
    • The entropy of the shortest allowed length of inputs MUST be greater than 10 bits.
    • The maximum entropy of all possible inputs MUST be greater than 18 bits.
    • MUST not replace any of the existing authentication methods (PIN, pattern, password) implemented and provided in AOSP.
    • MUST be disabled when the Device Policy Controller (DPC) application has set the password quality policy via the DevicePolicyManager.setPasswordQuality() method with a more restrictive quality constant than PASSWORD_QUALITY_SOMETHING .
  • The authentication method, if based on a physical token or the location, MUST NOT be treated as a secure lock screen unless it meets all following requirements:
  • The authentication method, if based on biometrics, MUST NOT be treated as a secure lock screen unless it meets all following requirements:
    • It MUST have a fall-back mechanism to use one of the primary authentication methods which is based on a known secret and meets the requirements to be treated as a secure lock screen.
    • It MUST be disabled and only allow the primary authentication to unlock the screen when the Device Policy Controller (DPC) application has set the keguard feature policy by calling the method DevicePolicyManager.setKeyguardDisabledFeatures(KEYGUARD_DISABLE_FINGERPRINT) .
    • It MUST have a false acceptance rate that is equal or stronger than what is required for a fingerprint sensor as described in section 7.3.10, or otherwise MUST be disabled and only allow the primary authentication to unlock the screen when the Device Policy Controller (DPC) application has set the password quality policy via the DevicePolicyManager.setPasswordQuality() method with a more restrictive quality constant than PASSWORD_QUALITY_BIOMETRIC_WEAK .
  • If the authentication method can not be treated as a secure lock screen, it:
  • If the authentication method is based on a physical token, the location, or biometrics that has higher false acceptance rate than what is required for fingerprint sensors as described in section 7.3.10, then it:

9.12.資料刪除

Devices MUST provide users with a mechanism to perform a "Factory Data Reset" that allows logical and physical deletion of all data except for the following:

  • The system image
  • Any operating system files required by the system image

All user-generated data MUST be deleted. This MUST satisfy relevant industry standards for data deletion such as NIST SP800-88. This MUST be used for the implementation of the wipeData() API (part of the Android Device Administration API) described in section 3.9 Device Administration .

Devices MAY provide a fast data wipe that conducts a logical data erase.

9.13。 Safe Boot Mode

Android provides a mode enabling users to boot up into a mode where only preinstalled system apps are allowed to run and all third-party apps are disabled. This mode, known as "Safe Boot Mode", provides the user the capability to uninstall potentially harmful third-party apps.

Android device implementations are STRONGLY RECOMMENDED to implement Safe Boot Mode and meet following requirements:

  • Device implementations SHOULD provide the user an option to enter Safe Boot Mode from the boot menu which is reachable through a workflow that is different from that of normal boot.

  • Device implementations MUST provide the user an option to enter Safe Boot Mode in such a way that is uninterruptible from third-party apps installed on the device, except for when the third party app is a Device Policy Controller and has set the UserManager.DISALLOW_SAFE_BOOT flag as true.

  • Device implementations MUST provide the user the capability to uninstall any third-party apps within Safe Mode.

9.14。 Automotive Vehicle System Isolation

Android Automotive devices are expected to exchange data with critical vehicle subsystems, eg, by using the vehicle HAL to send and receive messages over vehicle networks such as CAN bus. Android Automotive device implementations MUST implement security features below the Android framework layers to prevent malicious or unintentional interaction between the Android framework or third-party apps and vehicle subsystems. These security features are as follows:

  • Gatekeeping messages from Android framework vehicle subsystems, eg, allowlisting permitted message types and message sources.
  • Watchdog against denial of service attacks from the Android framework or third-party apps. This guards against malicious software flooding the vehicle network with traffic, which may lead to malfunctioning vehicle subsystems.

10. Software Compatibility Testing

Device implementations MUST pass all tests described in this section.

However, note that no software test package is fully comprehensive. For this reason, device implementers are STRONGLY RECOMMENDED to make the minimum number of changes as possible to the reference and preferred implementation of Android available from the Android Open Source Project. This will minimize the risk of introducing bugs that create incompatibilities requiring rework and potential device updates.

10.1. Compatibility Test Suite

Device implementations MUST pass the Android Compatibility Test Suite (CTS) available from the Android Open Source Project, using the final shipping software on the device. Additionally, device implementers SHOULD use the reference implementation in the Android Open Source tree as much as possible, and MUST ensure compatibility in cases of ambiguity in CTS and for any reimplementations of parts of the reference source code.

The CTS is designed to be run on an actual device. Like any software, the CTS may itself contain bugs. The CTS will be versioned independently of this Compatibility Definition, and multiple revisions of the CTS may be released for Android 7.1. Device implementations MUST pass the latest CTS version available at the time the device software is completed.

10.2. CTS Verifier

Device implementations MUST correctly execute all applicable cases in the CTS Verifier. The CTS Verifier is included with the Compatibility Test Suite, and is intended to be run by a human operator to test functionality that cannot be tested by an automated system, such as correct functioning of a camera and sensors.

The CTS Verifier has tests for many kinds of hardware, including some hardware that is optional. Device implementations MUST pass all tests for hardware that they possess; for instance, if a device possesses an accelerometer, it MUST correctly execute the Accelerometer test case in the CTS Verifier. Test cases for features noted as optional by this Compatibility Definition Document MAY be skipped or omitted.

Every device and every build MUST correctly run the CTS Verifier, as noted above. However, since many builds are very similar, device implementers are not expected to explicitly run the CTS Verifier on builds that differ only in trivial ways. Specifically, device implementations that differ from an implementation that has passed the CTS Verifier only by the set of included locales, branding, etc. MAY omit the CTS Verifier test.

11. Updatable Software

Device implementations MUST include a mechanism to replace the entirety of the system software. The mechanism need not perform “live” upgrades—that is, a device restart MAY be required.

Any method can be used, provided that it can replace the entirety of the software preinstalled on the device. For instance, any of the following approaches will satisfy this requirement:

  • “Over-the-air (OTA)” downloads with offline update via reboot.
  • “Tethered” updates over USB from a host PC.
  • “Offline” updates via a reboot and update from a file on removable storage.

However, if the device implementation includes support for an unmetered data connection such as 802.11 or Bluetooth PAN (Personal Area Network) profile, it MUST support OTA downloads with offline update via reboot.

The update mechanism used MUST support updates without wiping user data. That is, the update mechanism MUST preserve application private data and application shared data. Note that the upstream Android software includes an update mechanism that satisfies this requirement.

For device implementations that are launching with Android 6.0 and later, the update mechanism SHOULD support verifying that the system image is binary identical to expected result following an OTA. The block-based OTA implementation in the upstream Android Open Source Project, added since Android 5.1, satisfies this requirement.

Also, device implementations SHOULD support A/B system updates . The AOSP implements this feature using the boot control HAL.

If an error is found in a device implementation after it has been released but within its reasonable product lifetime that is determined in consultation with the Android Compatibility Team to affect the compatibility of third-party applications, the device implementer MUST correct the error via a software update available that can be applied per the mechanism just described.

Android includes features that allow the Device Owner app (if present) to control the installation of system updates. To facilitate this, the system update subsystem for devices that report android.software.device_admin MUST implement the behavior described in the SystemUpdatePolicy class.

12. Document Changelog

For a summary of changes to the Compatibility Definition in this release:

For a summary of changes to individuals sections:

  1. 介紹
  2. Device Types
  3. 軟體
  4. Application Packaging
  5. 多媒體
  6. Developer Tools and Options
  7. Hardware Compatibility
  8. 性能和功率
  9. 安全模型
  10. Software Compatibility Testing
  11. Updatable Software
  12. Document Changelog
  13. 聯絡我們

12.1。 Changelog Viewing Tips

Changes are marked as follows:

  • CDD
    Substantive changes to the compatibility requirements.

  • 文件
    Cosmetic or build related changes.

For best viewing, append the pretty=full and no-merges URL parameters to your changelog URLs.

13. 聯絡我們

You can join the android-compatibility forum and ask for clarifications or bring up any issues that you think the document does not cover.