Android 6.0 相容性定義

目錄

一、簡介

本文檔列舉了裝置與 Android 6.0 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 [參考資料，1 ] 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 6.0 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 6.0 相容，裝置實作必須滿足此相容性定義中提出的要求，包括透過引用合併的任何文件。

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 [參考資料, 2 ] 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。

在第 14 節中列出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。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。在第 14 節中包含的參考文獻中提供的任何技術細節均被視為包含在本相容性定義中。

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（「向後傾斜」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 [參考資料，3 ]。

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 [資源，4 ]。

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：

  • 必須聲明 android.hardware.type.automotive 功能。
  • 必須支援 uiMode = UI_MODE_TYPE_CAR [ 資源，5 ]。

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 6.0 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應該必須應該應該
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
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 [參考資料，6 ] 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。

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。

3.2.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 [參考資料 7 ] 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 包含 android.os.Build 類別 [ Resources, 8 ] 上的許多常數，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。該欄位必須具有 [ Resources, 9 ] 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 6.0，此欄位必須具有整數值 23。
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 6.0，此欄位必須具有整數值 23。
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_-]+$」。
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:6.0/LMYXX/3359:userdebug/測試密鑰

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_-]+$」。
串口硬體序號，在具有相同型號和製造商的設備之間必須可用且唯一。此欄位的值必須可編碼為 7 位元 ASCII 並符合正規表示式「^([a-zA-Z0-9]{6,20})$」。
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。它必須表明該版本包含透過指定的 Android 公共安全公告發布的所有安全性修補程式。它必須採用 [YYYY-MM-DD] 格式，與公共安全公告的 Android 安全補丁等級字串之一匹配，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

裝置實作必須遵循 Android 的鬆散耦合意圖系統，如下節所述。 「榮幸」意味著裝置實現者必須提供一個 Android Activity 或 Service，指定一個匹配的 Intent 過濾器，該過濾器綁定到每個指定的 Intent 模式並為其實現正確的行為。

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

裝置實作應該包括適當的核心 Android 應用程序，但必須包括一個元件，該元件實現由這些核心 Android 應用程式的所有「公共」活動或服務元件定義的相同意圖模式。請注意，當屬性 android:exported 不存在或值為 true 時，Activity 或 Service 元件被視為「公有」。

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 [參考資料，140 ]。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 [參考資料，141 ] 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 Android.* 或 com.android.* 命名空間中的 ACTION、CATEGORY 或其他鍵字串來支援任何新意圖或廣播意圖模式的 Android 元件。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：

  • 如果裝置實作報表 android.software.home_screen [資源，10 ]，則必須遵守 android.settings.HOME_SETTINGS 意圖，以顯示主畫面的預設應用程式設定選單
  • 如果裝置實作報表 android.hardware.telephony [資源，11 ]，則必須提供一個設定選單，該選單將呼叫 android.provider.Telephony.ACTION_CHANGE_DEFAULT 意圖來顯示一個對話框以變更預設 SMS 應用程式
  • 如果裝置實作報表 android.hardware.nfc.hce，則必須遵守 android.settings.NFC_PAYMENT_SETTINGS 意圖，以顯示點擊付款的預設應用程式設定選單 [資源，10 ]

3.3.本機 API 相容性

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。

如果裝置實現包含對 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 參數來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 從最受青睞的到最不受青睞的排序
  • 必須透過上述參數僅報告最新版本的 Android NDK ABI 管理文件 [參考資料，12 ] 中記錄和描述的 ABI，並且必須包括對高級 SIMD（又稱 NEON）[參考資料，13 ] 擴展的支持
  • 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

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：

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

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。

請注意，裝置實作必須包含 libGLESv3.so，並且它必須符號連結（符號連結）到 libGLESv2.so。反過來，必須匯出 NDK 版本 android-21 中定義的所有 OpenGL ES 3.1 和 Android 擴充包 [資源，14 ] 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。

裝置實作（如果包含名為 libvulkan.so 的本機函式庫）必須匯出函數符號並提供 Vulkan 1.0 API 的實作以及由 Khronos Group 定義的 VK_KHR_surface、VK_KHR_swapchain 和 VK_KHR_android_surface 擴充，並透過 Khronos 擴充功能測試。

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上游 Android 開源專案中列出的上述程式庫的實作。

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：”，後跟裝置支援的任何可選 ARMv7 CPU 功能的列表
  • “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 [參考資料，15 ]。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 6.0 上游 Android 開源專案的 Chromium 建置。此版本包括一組針對 WebView 的特定功能和安全修復程序 [參考資料，16 ]。
  • 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 元件應該包含對盡可能多的 HTML5 功能的支持，並且如果它支援該功能，則應該符合 HTML5 規範 [參考資料，17 ]。

3.4.2.瀏覽器相容性

Android Television、Watch 和 Android Automotive 實作可以省略瀏覽器應用程序，但必須支援第 3.2.3.1 節中所述的公共意圖模式。所有其他類型的裝置實作必須包括用於一般使用者 Web 瀏覽的獨立瀏覽器應用程式。

獨立瀏覽器可以基於 WebKit 以外的瀏覽器技術。但是，即使使用備用瀏覽器應用程序，提供給第三方應用程式的 android.webkit.WebView 元件也必須基於 WebKit，如3.4.1 節中所述。

實作可以在獨立的瀏覽器應用程式中提供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替代品）應該盡可能支援 HTML5 [參考資料，17 ]。設備實作至少必須支援與 HTML5 相關的每個 API：

此外，設備實作必須支援 HTML5/W3C webstorage API [參考資料，21 ]，並且應該支援 HTML5/W3C IndexedDB API [參考資料，22 ]。請注意，隨著 Web 開發標準機構逐漸轉向支援 IndexedDB 而不是 Webstorage，IndexedDB 預計將成為 Android 未來版本中的必要組件。

3.5. API 行為相容性

每個 API 類型（託管、軟體、本機和 Web）的行為必須與上游 Android 開源專案的首選實作一致 [參考資料, 2 ]。一些特定的兼容性領域是：

  • 設備不得更改標準意圖的行為或語意。
  • 設備不得更改特定類型的系統元件（例如服務、活動、ContentProvider 等）的生命週期或生命週期語意。
  • 設備不得更改標準權限的語意。

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LT; uses-librarygt; Maginigry）受到增加的記憶體影響使用這種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[ Resources，23 ]。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，設備實現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定義了一種元件類型和相應的API和生命週期，該類型允許應用程式向最終用戶傳播「 AppWidget」 [ Resources，24 ]，該功能強烈建議在Handheld裝置實作上支援。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，並揭示使用者介面提供的添加，配置，查看和刪除appwidgets直接在啟動器中。
  • 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[ Resources，24 ]中的App Widget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包括API，允許開發人員使用裝置的硬體和軟體功能通知用戶著名事件[ Resources，25 ]。

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，此實作必須正確渲染API [APIS [資源26 ]或狀態/系統欄圖標樣式指南[資源，27 ]中提供的所有資源（圖標，動畫檔案等） Android電視裝置包含不顯示通知的可能性。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設備實現（當使此類通知都可見時，必須正確執行富裕和主題通知，並包括標題/名稱，圖標，Android API中記錄的文本[ Resources，28 ]。

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。

Android包括API [ Resources，29 ]，允許開發人員將搜尋納入其應用程序，並將其應用程式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設備實作應在裝置上實現助手來處理輔助操作[資源，30 ]。

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當前上下文的多少資訊[ Resources，31 ]。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。

3.8.5。烤麵包

應用程式可以使用「吐司」 API向最終用戶顯示短的非模式字串，該字串在短時間後消失[資源，32 ]。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包含一個「 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所定義的Holo主題外觀和感覺[ Resources，33 ]。設備實作不得改變暴露於應用程式的任何Holo主題屬性[資源，34 ]。

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[資源，35 ]。

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[資源，34 ]。

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。當應用程式請求輕型狀態列時，Android裝置實作必須將系統狀態圖示的顏色變更為黑色[ Resources，34 ]。

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將一個或多個「即時桌布」暴露於最終用戶[ Resources，36 ]。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

由於最近的功能導航鍵是可選的，因此實現概述螢幕的要求是Android電視設備和Android手錶設備的可選要求。

上游Android原始碼包括概述畫面[資源，37 ]，這是一個系統級使用者介面，用於任務切換和顯示最近訪問的活動和任務，並使用應用程式圖形狀態的縮圖映像在使用者上次離開應用程序時。設備實作包括第7.2.3節中詳細列出的RECENTS功能導航密鑰可能會更改接口，但必須滿足以下要求：

  • 必須顯示關聯的恢復作為一個一起移動的群組。
  • 必須至少支援多達6個顯示的活動。
  • 至少應該一次顯示4個活動的標題。
  • 應顯示重點，圖標，螢幕標題。
  • 必須實現螢幕固定行為[資源，38 ]，並為使用者提供設定選單以切換該功能。
  • 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。

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[ Resources，39 ]。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已從Android 5.0中棄用，而有利於媒體通知模板，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[ Resources，40 ]作為鎖定螢幕通知。裝置實作必須正確渲染媒體通知模板，這是第3.8.3節所述的鎖定畫面通知的一部分。

3.8.11。夢

Android包括對稱為Dreams的互動式螢幕保護程式的支援[ Resources，41 ]。當連接到電源的設備空閒或停靠在桌上碼頭中時，夢想使用戶可以與應用程式互動。 Android Watch設備可能會實現夢想，但是其他類型的設備實現應包括對夢想的支持，並為用戶提供設定選項，以響應Android.settings.dream_settings的意圖來配置夢想。

3.8.12。地點

當設備具有能夠提供位置座標的硬體感測器（例如GPS）時，必須在設定中的位置選單中顯示位置模式[ Resources，42 ]。

3.8.13。 Unicode和字體

Android包含對顏色表情符號字元的支援。當Android裝置實作包含IME時，裝置應為Unicode 6.1中定義的表情符號字元的使用者提供輸入方法[ Resources，43 ]。所有設備都必須能夠在顏色字形中呈現這些表情符號字元。

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。

3.9.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，例如執行密碼原則或透過Android裝置管理API執行遠端抹除[ Resources，44 ]。設備實作必須提供設備上的PolicyManager類別[資源，45 ]的實作。設備實現包括對PIN（數字）或密碼（字母數字）的鎖定螢幕的支持，必須支援Android SDK文件中定義的設備管理策略[ Resources，44 ]，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

如果裝置實作將android.software.device_admin功能聲明，則盒子設定流必須使將裝置策略控制器（DPC）應用程式輸入裝置擁有者應用程式[ Resources，46 ]成為可能。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。

裝置擁有者的設定流程（由Android.app.action.provision_managed_device [ Resources，47 ]引發的流程）使用者體驗必須與AOSP實作一致

如果裝置實作報表android.hardware.nfc，即使在盒子外設定流期間，它也必須啟用NFC，以便允許對裝置擁有者的NFC提供[ Resources，48 ]。

3.9.1.2託管個人資料供應

如果裝置實作聲明Android.software.managed_users，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[ Resources，49 ]

託管的設定檔設定流程（由Android.app.action.provision_managed_profile [ Resources，50 ]引發的流程）使用者體驗必須與AOSP實作保持一致

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 API支援託管設定檔
  • 允許建立一個和只有一個託管資料[ 資源，50 ]
  • 使用圖示徽章（類似於AOSP上游工作徽章）來表示託管應用程式和小部件以及其他徽章UI元素，例如recents＆Notifications
  • 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時以及何時在託管設定檔中（action_user_present），並且前景應用程式在託管的設定檔中
  • 如果存在託管設定檔的地方，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，如果由裝置原則控制器啟用
  • 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。
    • 主用戶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。
  • 如果設備策略控制器允許，請確保預設撥號器可以從主設定檔中尋找呼叫者資訊（如果存在）。
  • 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。

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[ Resources ，51 ]。

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。
  • 設備實現（不包括Android汽車）必須支援透過Android的第三方可訪問性服務實現。
  • 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。

此外，設備實現應在設備上提供可訪問性服務的實現，並應為使用者提供在設備設定期間啟用可訪問性服務的機制。可訪問性服務的開源實作可從眼睛免費專案[資源，53 ]。

3.11。文字轉語音

Android包括允許應用程式使用文字轉語音（TTS）服務的API，並允許服務提供者提供TTS服務的實現[ Resources，54 ]。裝置實作報表功能Android.hardware.audio.Output必須符合與Android TTS框架相關的這些要求。

Android汽車實施：

  • 必須支援Android TTS框架API。
  • 可能支援安裝第三方TTS引擎。如果得到支持，合作夥伴必須提供一個可存取用戶的接口，該接口允許用戶選擇用於系統級別的TTS引擎。

所有其他設備實作：

  • 必須支援Android TTS框架API，並應包括支援裝置上可用語言的TTS引擎。請注意，上游Android開源軟體包含功能齊全的TTS引擎實作。
  • 必須支援安裝第三方TTS發動機
  • 必須提供一個可訪問用戶的接口，該接口允許用戶選擇用於系統級別的TTS引擎

3.12。電視輸入框架

Android電視輸入框架（TIF）簡化了直播內容到Android電視裝置的交付。 TIF提供了一個標準API來建立控制Android電視裝置的輸入模組。 Android電視設備實作必須支援電視輸入框架[資源，55 ]。

支援TIF的裝置實作必須聲明平台功能Android.software.live_tv。

3.12.1。電視應用程式

任何聲明對直播電視支援的裝置實作都必須具有已安裝的電視應用程式（電視應用程式）。 Android開源專案提供了電視應用程式的實作。

預設的電視應用程式必須從已安裝的輸入和第三方輸入中提供對頻道的存取。請注意，已安裝的輸入包括預設情況下提供的所有輸入，無論它們是否基於TIF。

電視應用必須提供安裝和使用電視頻道的設施[資源，56 ]並滿足以下要求：

  • 設備實作必須允許基於第三方TIF的輸入（第三方輸入）[資源，57 ]可以安裝和管理。
  • 設備實作可能會在預先安裝的基於TIF的輸入（安裝輸入）[資源，58 ]和第三方輸入之間提供視覺分離。
  • 裝置實作不得顯示第三方輸入超過電視應用程式的單一導航操作（即從電視應用程式中擴展第三方輸入清單）。

3.12.1.1。電子程式指南

Android電視設備實作必須顯示資訊和互動式覆蓋層，其中必須包括從TVContracts中的值產生的電子程式指南（EPG）。程式欄位[ Resources，59 ]。 EPG必須符合以下要求：

  • EPG必須顯示所有已安裝的輸入和第三方輸入的資訊。
  • EPG可以在已安裝的輸入和第三方輸入之間提供視覺分離。
  • 強烈建議使用EPG顯示同等突出的安裝輸入和第三方輸入。 EPG不得顯示第三方輸入超過單一導覽操作，而非EPG上的已安裝輸入。
  • 關於頻道更改，裝置實作必須顯示目前播放程式的EPG資料。

3.12.1.2。導航

Android電視設備輸入裝置（即遙控器，遠端控制應用程式或遊戲控制器）必須允許透過D-PAD導航到螢幕的所有可操作部分。當螢幕上沒有可操作的部分時，必須使用D-PAD上下的D-PAD來更改即時電視頻道。

電視應用程式應透過CEC將關鍵事件傳遞給HDMI輸入。

3.12.1.3。電視輸入應用程式鏈接

Android電視設備實現必須支援電視輸入應用程式鏈接，該鏈接允許所有輸入提供從當前活動到另一個活動的活動鏈接（即從實時編程到相關內容的鏈接）[資源，60 ]。電視應用程式必須顯示電視輸入應用程式在提供時連結。

4.應用程式包裝相容性

設備實作必須安裝並運行由官方Android SDK中包含的「 AAPT」工具產生的Android「 .APK」檔案[ Resources，61 ]。

設備實作不得擴充.APK [資源，62 ]，Android清單[資源，49 ]，Dalvik bytecode [ Resources 23 ]或RenderScript字節碼的格式，以防止這些檔案安裝並在其他相容設備。

5.多媒體相容性

5.1。媒體編解碼器

設備實作必須支援Android SDK文檔[資源，64 ]中指定的核心媒體格式，除非本文檔明確允許。具體而言，設備實作必須支援媒體格式，編碼器，解碼器，檔案類型和容器格式在下表中定義，並透過MediaCodeClist [ Resources，65 ]進行了報告。設備實作還必須能夠解碼其CamcorderProfile [ Resources，66 ]中報告的所有設定文件，並且必須能夠解碼其可以編碼的所有格式。所有這些編解碼器都是在Android開源專案的首選Android實作中作為軟體實現的。

請注意，Google和開放手機聯盟都沒有做出任何代碼器，即這些編解碼器沒有第三方專利。建議打算在硬體或軟體產品中使用此原始碼的人，該程式碼的實現（包括開源軟體或共享軟體）可能需要相關專利持有人的專利許可。

5.1.1。音訊編解碼器

格式/編解碼器編碼器解碼器細節支援的文件類型/容器格式
MPEG-4 AAC設定文件
（AAC LC）		需要1必需的支援單聲道/立體聲/5.0/5.1 2的內容，其標準取樣率從8到48 kHz。
  • 3GPP（.3GP）
  • MPEG-4（.mp4，.m4a）
  • ADTS RAW AAC（.AAC，在Android 3.1+中解碼，在Android 4.0+中編碼，不支援ADIF）
  • mpeg-ts（.ts，不可尋求，Android 3.0+）
MPEG-4 HE AAC設定檔（AAC+）需要1
（Android 4.1+）		必需的支援單聲道/立體聲/5.0/5.1 2的內容，其標準取樣率從16到48 kHz。
MPEG-4 HE AACV2
設定檔（增強AAC+）		必需的支援單聲道/立體聲/5.0/5.1 2的內容，其標準取樣率從16到48 kHz。
AAC ELD（增強的低延遲AAC）需要1
（Android 4.1+）		必需的
（Android 4.1+）		支援單聲道/立體聲含量，標準取樣率從16到48 kHz。
AMR-NB需要3需要3 4.75至12.2 kbps @ 8 kHz採樣3GPP（.3GP）
AMR-WB需要3需要3 9速率從6.60 kbit/s到23.85 kbit/s取樣 @ 16 kHz
FLAC必需的
（Android 3.1+）		單聲道/立體聲（無多聲道）。最高48 kHz的樣品速率（但建議在44.1 kHz輸出的設備上使用高達44.1 kHz，因為48至44.1 kHz的傾斜降低器不包括低通濾波器）。建議使用16位；沒有抖動適用於24位。僅FLAC（.flac）
MP3必需的單一/立體聲8-320kbps常數（CBR）或可變位元率（VBR） mp3（.mp3）
MIDI必需的MIDI類型0和1。DLS版本1和2。XMF和移動XMF。支援鈴聲格式RTTTL/RTX，OTA和IMELODY
  • 類型0和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需要4
（Android 4.1+）		必需的16位元線性PCM（速率達到硬體限制）。設備必須支援8000、11025、16000和44100 Hz頻率的原始PCM記錄的取樣率。波（.wav）
作品必需的
（Android 5.0+）		 Matroska（.MKV）

1定義Android.hardware.microphone但可選的Android Watch設備實現的設備實現所需的1。

2僅需5.0/5.1內容的下降；錄製或渲染超過2個頻道是可選的。

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 Encoder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)
WebP必需的必需的WebP (.webp)

5.1.3. Video Codecs

Format/Codec Encoder解碼器細節Supported File Types/
Container Formats
H.263 REQUIRED 1 REQUIRED 2
  • 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 in [ Resources, 68 ].

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. Video Encoding

Video codecs are optional for Android Watch device implementations.

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

Android device implementations with H.264 codec support, MUST support Baseline Profile Level 3 and the following SD (Standard Definition) video encoding profiles and SHOULD support Main Profile Level 4 and the following HD (High Definition) video encoding profiles. 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 px
Video frame rate 20 fps 30 fps 30 fps 30 fps
視訊比特率384 Kbps 2 Mbps 4 Mbps 10 Mbps

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

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 px
Video frame rate 30 fps 30 fps 30 fps 30 fps
視訊比特率800 Kbps 2 Mbps 4 Mbps 10 Mbps

1 When supported by hardware.

5.3. Video Decoding

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裝置.

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

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

Android device implementations with H.264 decoders, MUST support Main Profile Level 3.1 and the following SD video decoding profiles and SHOULD support the HD decoding profiles. Android Television devices MUST support High Profile Level 4.2 and the HD 1080p decoding profile.

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 px
Video frame rate 30 fps 30 fps 60 fps 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.

Android device implementations when supporting VP8 codec as described in section 5.1.3 , MUST support the following SD decoding profiles and SHOULD support the HD decoding profiles. Android Television devices MUST support the HD 1080p 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 px
Video frame rate 30 fps 30 fps 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.

Android device implementations, when supporting VP9 codec as described in section 5.1.3 , MUST support the following SD video decoding profiles and SHOULD support the HD decoding profiles. Android Television devices are STRONGLY RECOMMENDED to support the HD 1080p decoding profile and SHOULD support the UHD decoding profile. When 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) HD 720p 1 HD 1080p 2 UHD 2
視訊解析度320 x 180 px 640 x 360 px 1280 x 720 px 1920 x 1080 px 3840 x 2160 px
Video frame rate 30 fps 30 fps 30 fps 60 fps 60 fps
視訊比特率600 Kbps 1.6 Mbps 4 Mbps 5 Mbps 20 Mbps

1 Required for Android Television device implementations, but for other type of devices only when supported by hardware.

2 STRONGLY RECOMMENDED for existing Android Television device implementations when supported by hardware.

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 following SD video decoding profiles and SHOULD support the HD decoding profiles. Android Television devices are STRONGLY RECOMMENDED to support the UHD decoding profile and the HD 1080p decoding profile. If the HD 1080p decoding profile is supported, it MUST support the Main Profile Level 4.1 Main tier. If UHD decoding is supported, then it MUST support Main10 Level 5 Main Tier profile.

SD (Low quality) SD (High quality) HD 720p 1 HD 1080p 2 UHD 2
視訊解析度352 x 288 px 640 x 360 px 1280 x 720 px 1920 x 1080 px 3840 x 2160 px
Video frame rate 30 fps 30 fps 30 fps 60 fps 2 60 fps
視訊比特率600 Kbps 1.6 Mbps 4 Mbps 10 Mbps 20 Mbps

1 Required for Android Television device implementations, but for other type of devices only when supported by hardware.

2 STRONGLY RECOMMENDED for existing Android Television device implementations when supported by hardware.

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

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. Audio Playback

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 [ Resources, 69 ]. 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).

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 can be heard by an external listener or observed by a transducer.
  • 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 an external sound is presented to the device and when an application reads the corresponding frame of PCM-coded data.
  • 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 variance among separate measurements of cold output latency values.
  • cold input jitter . The variance 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 term allows processing time for the app and 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; see NDK_root/docs/opensles/index.html.

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 [ Resources, 70 ]. 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. Network Protocols

Devices MUST support the media network protocols for audio and video playback as specified in the Android SDK documentation [ Resources, 64 ]. Specifically, devices MUST support the following media network protocols:

  • RTSP (RTP, SDP)
  • HTTP(S) progressive streaming
  • HTTP(S) Live Streaming draft protocol, Version 3 [ Resources, 71 ]

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 [ Resources, 70 ].

The MIDI-capable hardware transports are:

  • USB host mode (section 7.7 USB)
  • USB peripheral mode (section 7.7 USB)

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.

MIDI over Bluetooth LE acting in central role (section 7.4.3 Bluetooth) is in trial use status. A device implementation that reports feature android.software.midi, and which provides generic non-MIDI connectivity over Bluetooth LE, SHOULD support MIDI over Bluetooth LE.

5.10. Professional Audio

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 [ Resources, 70 ].

  • 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 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) .

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:

Device implementations MUST support all adb functions as documented in the Android SDK including dumpsys [ Resources, 73 ]. 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.

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.

Device implementations MUST include the Monkey framework, and make it available for applications to use.

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. Developer Options

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 [ Resources, 77 ]. 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.

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. [ Resources, 70 ]

7.1. Display and Graphics

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 [ Resources, 78 ]. 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 [ Resources, 78 ] 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.

此外，

  • Android Watch devices MUST have a screen with the physical diagonal size in the range from 1.1 to 2.5 inches.
  • 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

Android Watch devices MAY have an aspect ratio of 1.0 (1:1).

The screen aspect ratio MUST be a value from 1.3333 (4:3) to 1.86 (roughly 16:9), but Android Watch devices MAY have an aspect ratio of 1.0 (1:1) because such a device implementation will use a UI_MODE_TYPE_WATCH as the android.content.res.Configuration.uiMode.

7.1.1.3. Screen Density

The Android UI framework defines a set of standard logical densities to help application developers target application resources. Device implementations MUST report only one of the following logical Android framework densities through the android.util.DisplayMetrics APIs, and MUST execute applications at this standard density and MUST NOT change the value at at any time for the default display.

  • 120 dpi (ldpi)
  • 160 dpi (mdpi)
  • 213 dpi (tvdpi)
  • 240 dpi (hdpi)
  • 280 dpi (280dpi)
  • 320 dpi (xhdpi)
  • 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.

7.1.2. Display Metrics

Device implementations MUST report correct values for all display metrics defined in android.util.DisplayMetrics [ Resources, 79 ] and MUST report the same values regardless of whether the embedded or external screen is used as the default display.

7.1.3. Screen Orientation

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 or 3.1 on devices capable of supporting it. Device implementations MUST also support Android RenderScript, as detailed in the Android SDK documentation [ Resources, 80 ].

Device implementations MUST also correctly identify themselves as supporting OpenGL ES 1.0, OpenGL ES 2.0, OpenGL ES 3.0 or OpenGL 3.1.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 or 3.1 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 or 3.1, libGLESv2.so MUST export the corresponding function symbols in addition to the OpenGL ES 2.0 function symbols.

In addition to OpenGL ES 3.1, Android provides an extension pack with Java interfaces [ Resources, 81 ] and native support for advanced graphics functionality such as tessellation and the ASTC texture compression format. Android device implementations MAY support this extension pack, and—only if fully implemented—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 [ Resources, 82 ].

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 [ Resources, 82 ].

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 [ Resources, 83 ].

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. Screen Technology

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 [ Resources, 84 ].

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 [ Resources, 85 ] (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 [ Resources, 85 ].
  • 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 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 6.0 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 6.0, 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 with the support of the Assist action [ Resources, 30 ] MUST make this accessible with a single action (eg tap, double-click, or gesture) when other navigation keys are visible, and are STRONGLY RECOMMENDED to use the long-press on the Home button or software key as the single action.

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 [ Resources, 85 ] 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 [ Resources, 86 ] 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 [ Resources, 87 ].
  • 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 [ Resources, 87 ].
  • 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 [ Resources, 87 ].
  • 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 Android Button
甲1 0x09 0x0001 KEYCODE_BUTTON_A (96)
乙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 [ Resources, 88 ]

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 [ Resources, 87 ]

Analog Controls 1 HID Usage Android Button
Left Trigger 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 [ Resources, 87 ]

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 [ Resources, 88 ].

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 [ Resources, 89 ]. For example, device implementations:

  • MUST accurately report the presence or absence of sensors per the android.content.pm.PackageManager class [ Resources, 70] .
  • 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 [ Resources, 90 ].
  • 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 requirement 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 [ Resources, 91 ].
  • 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 [ Resources, 89 ] 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 [ Resources, 92 ]. If a device implementation includes a composite sensor it MUST implement the sensor as described in the Android Open Source documentation on composite sensors [ Resources, 92 ].

Some Android sensors support a “continuous” trigger mode, which returns data continuously [ Resources, 93 ].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 swue 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. Accelerometer

Device implementations SHOULD include a 3-axis accelerometer. Android Handheld devices 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 [ Resources, 94 ].
  • 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 [ Resources, 90 ].
  • 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. Magnetometer

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 [ Resources, 90 ].
  • 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 µ.
  • 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 receiver. If a device implementation does include a GPS receiver, it SHOULD include some form of“assisted GPS” technique to minimize GPS lock-on time.

7.3.4. Gyroscope

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.

7.3.7. Photometer

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

7.3.8. Proximity Sensor

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 maxmium measurement frequency of 200 Hz or higher
    • MUST have a measurement noise not above 400uG/√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
  • 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 maxmium measurement frequency of 200 Hz or higher
    • MUST have a measurement noise not above 0.014°/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 maxmium 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
  • 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 millisconds of error.
  • The latency of delivery of samples to the HAL SHOULD be below 5 milliseconds from the instant the data is available on the physical sensor hardware.
  • 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 [ Resources, 95 ].
  • 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 [ Resources, 96 ].
  • 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.

7.4. Data Connectivity

7.4.1. Telephony

“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.

7.4.2. IEEE 802.11 (Wi-Fi)

Android Television device implementations MUST include Wi-Fi support.

Android Television device implementations MUST include support for one or more forms of 802.11 (b/g/a/n, etc.) and other types of Android device implementation 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 [ Resources, 97 ].
  • 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. Wi-Fi Direct

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 [ Resources, 98 ]. 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.

Android Television device implementations MUST include support for Wi-Fi Tunneled Direct Link Setup (TDLS).

Android Television device implementations MUST include support for Wi-Fi Tunneled Direct Link Setup (TDLS) and other types of Android device implementations SHOULD include support for Wi-Fi TDLS as described in the Android SDK Documentation [ Resources, 99 ]. 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 and Automotive implementations MUST support Bluetooth. Android Television implementations MUST support Bluetooth and Bluetooth LE.

Android includes support for Bluetooth and Bluetooth Low Energy [ Resources, 100 ]. 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 Television device implementations MUST support Bluetooth and Bluetooth LE.

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 [ Resources, 100 ].
  • 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 [ Resources, 101 ], 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.BluetoothAdapater.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 [ Resources, 70 ].
  • 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 [ Resources, 102 ] 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 [ Resources, 103 ]
      • SNEP 1.0 (defined by the NFC Forum)
    • MUST include support for Android Beam [ Resources, 104 ]:
      • 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 [ Resources, 105 ].
      • 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” [ Resources, 106 ] and “Bluetooth Secure Simple Pairing Using NFC version 1.0” [ Resources, 107 ] 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 and 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 [ Resources, 108 ].

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 [ Resources, 70 ]. 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 [ Resources, 70 ], 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. Sync Settings

Device implementations MUST have the master auto-sync setting on by default so that the method getMasterSyncAutomatically() returns “true” [ Resources, 109 ].

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 SHOULD be possible for an application to simultaneously allocate 3 bitmaps equal to the size of the images produced by the largest-resolution camera sensor on the device.

7.5.1. Rear-Facing Camera

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. Front-Facing Camera

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()[ Resources, 110 ] 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 with USB host mode MAY include support for an external camera that connects to the USB port. If a device includes support for an external camera, it:

  • MUST declare the platform feature android.hardware.camera.external and android.hardware camera.any.
  • MUST support USB Video Class (UVC 1.0 or higher).
  • MAY support multiple cameras.

Video compression (such as MJPEG) support is RECOMMENDED to enable transfer of high-quality unencoded streams (ie raw or independently compressed picture streams). Camera-based video encoding MAY be supported. If so, 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 [ Resources, 111 ], 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 [ Resources, 112 ].

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 described in the Android SDK [ Resources, 113 ] and report the appropriate framework feature flags [ Resources, 114 ].

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 [ Resources, 114 ]; 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。 Memory and Storage

7.6.1. Minimum Memory and Storage

Android Television devices MUST have at least 5GB 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
 424MB 704MB
  • xhdpi or higher on small/normal screens
  • hdpi or higher on large screens
  • mdpi or higher on extra large screens
 512MB 832MB
  • 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 5GB and other device implementations MUST have at least 1.5GB of non-volatile storage available for application private data. That is, the /data partition MUST be at least 5GB for Android Television devices and at least 1.5GB for other device implementations. Device implementations that run Android are STRONGLY RECOMMENDED to have at least 3GB 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 [ Resources, 115 ]. 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 Linux path /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 [ Resources, 116 ].
  • 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 [ Resources, 117 ].

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.

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 future platform releases.
  • The port SHOULD either 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 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 [ Resources, 118 ].
    • MUST support establishing an AOA protocol based communication on first time connection with a USB host machine that acts as an accessory, without the need for the user to change the default USB mode.
    • MUST implement the USB audio class as documented in the Android SDK documentation [ Resources, 119 ].
    • And also 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 [ Resources, 120 ]. 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 Type-C resistor standard.
  • The value of iSerialNumber in USB standard device descriptor MUST be equal to the value of android.os.Build.SERIAL.

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 [ Resources, 119 ].
  • 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 [ Resources, 121 ].
  • 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 [ ] for USB Type-C connectors or using Charging Downstream Port(CDP) output current range as specified in the USB Battery Charging Specification, Revision 1.2 [ Resources, 120 ] for Micro-AB connectors.

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 [ Resources, 122 ], 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.
  • SHOULD 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
  • SHOULD support the detection and mapping 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 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 (SNR) 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.

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

All apps exempted from App Standby and/or Doze mode 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.

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 [ Resources, 123 ].
    • 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 [ Resources, 124 ].
  • MUST honor the android.intent.action.POWER_USAGE_SUMMARY intent and display a settings menu that shows this power usage [ Resources, 125 ].

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 [ Resources, 126 ] 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 [ Resources, 126 ]. 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 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 [ Resources, 126 ].

9.3. Filesystem Permissions

Device implementations MUST support the Android file access permissions model as defined in the Security and Permissions reference [ Resources, 126 ].

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.
  • and 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 [ Resources, 127 ]. Device implementations MAY enable multiple users, but when enabled MUST meet the following requirements related to multi-user support [ Resources, 128 ]:

  • 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 [ Resources, 126 ].
  • 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 primary 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 [ Resources, 129 ] for primary external storage.

9.6。 Premium SMS Warning

Android includes support for warning users of any outgoing premium SMS message [ Resources, 130 ]. 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 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 external/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.

Device implementations SHOULD retain the default SELinux policy provided in the external/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.

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 traffic through a proxy server or VPN gateway by default (for example, preloading a mple service with android.VPNmission.CONTROL_VPN that機制。

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. Full-Disk Encryption

Optional for Android device implementations without a lock screen.

If the device implementation supports a secure lock screen reporting " true " for KeyguardManager.isDeviceSecure() [ Resources, 131 ], and is not a device with restricted memory as reported through the ActivityManager.isLowRamDevice() method, then the device MUST support full-disk encryption [ Resources, 132 ] 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 full-disk encryption and with Advanced Encryption Standard (AES) crypto performance above 50MiB/sec, the full-disk 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 full-disk encryption disabled by default, such a device cannot meet the requirement through a system software update and thus MAY be exempted.

Encryption 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. Other than when in active use, the encryption key SHOULD be AES encrypted with the lockscreen passcode stretched using a slow stretching algorithm (eg PBKDF2 or scrypt). If the user has not specified a lockscreen passcode 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. Verified Boot

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)

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 50MiB/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 [ Resources, 133 ] allows app developers to store cryptographic keys in a container and use them in cryptographic operations through the KeyChain API [ Resources, 134 ] or the Keystore API [ Resources, 135 ].

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 SHOULD have an exponential backoff algorithm as implemented in the Android Open Source Project.
  • When the device implementation supports a secure lock screen and has a secure hardware such as a Secure Element (SE) where a Trusted Execution Environment (TEE) can be implemented, then it:
    • Is STRONGLY RECOMMENDED to back up the keystore implementation with the secure hardware. The upstream Android Open Source Project provides the Keymaster Hardware Abstraction Layer (HAL) implementation that can be used to satisfy this requirement.
    • MUST perform the lock screen authentication in the secure hardware if the device has a hardware-backed keystore implementation 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) that can be used to satisfy this requirement [ Resources, 136 ].

Note that while the above TEE-related requirements are stated as STRONGLY RECOMMENDED, the Compatibility Definition for the next API version is planned to changed these to REQUIRED. If a device implementation is already launched on an earlier Android version and has not implemented a trusted operating system on the secure hardware, such a device might not be able to meet the requirements through a such a device might not be able to meet the requirements through a ject tooxledate Iwated 月 Iwate thr. 。

9.12. Data Deletion

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 system image and data in other partitions that can be regarded as part of the system image. 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.

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) [ Resources, 137 ] 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 6.0. 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:

  • Android Automotive implementations SHOULD support OTA downloads with offline update via reboot.
  • All other device implementations 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.

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 [ Resources, 138 ].

12. Document Changelog

The following table contains a summary of the changes to the Compatibility Definition in this release.

部分Summary of changes
各種各樣的Replaced instances of the "encouraged" term with "RECOMMENDED"
2. Device Types Update for Android Automotive implementations
3.2.2. Build Parameters Additions for the hardware serial number and for the security patch level of a build
3.2.3.2. Intent Resolution Section renamed from "Intent Overrides" to "Intent Resolution," with new requirements related to authoritative default app linking
3.3.1. Application Binary Interfaces Additions for Android ABI support; change related to Vulkan library name
3.4.1. WebView Compatibility Change for the user agent string reported by the WebView
3.7. Runtime Compatibility Updates to memory allocation table
3.8.4.搜尋Updates regarding Assistant requirements
3.8.6.主題Added requirement to support black system icons when requested by the SYSTEM_UI_FLAG_LIGHT_STATUS_BAR flag
3.8.8. Activity Switching Relaxed Overview title count requirement.
3.8.10. Lock Screen Media Control Lock Screen Media Control to refer to 3.8.3 in detail.
3.9.1. Device Provisioning Contains new sections for device owner provisioning and managed profile provisioning
3.9.2. Managed Profile Support New section with requirements for device support of managed profile functionality
3.12.1.電視應用程式Added section to clarify TV App requirements for Android Television devices
3.12.1.1. Electronic Program Guide Added section to clarify EPG requirements for Android Television devices
3.12.1.2.導航Added section to clarify TV App navigation requirements for Android Television devices
3.12.1.3. TV input app linking Added section to clarify TV input app linking support requirements for Android Television devices
5.1. Media Codecs Updates regarding support for core media formats and decoding.
5.1.3. Video Codecs Changes and additions related to Android Televisions
5.2. Video Encoding Changes for encoders
5.3. Video Decoding Changes for decoders, including regarding support for dynamic video resolution, frame rate switching, and more
5.4.聲音錄製Additions related to audio capture
5.6. Audio Latency Update regarding reporting of support for low-latency audio
5.10. Professional Audio General updates for professional audio support; updates for mobile device (jack) specifications, USB audio host mode, and other updates
5.9. Musical Instrument Digital Interface (MIDI) Added new section on optional Musical Instrument Digital Interface (MIDI) support
6.1.開發者工具Update for drivers supporting Windows 10
7.1.1.3. Screen Density Updates for screen density, for example related to an Android watch
7.2.3. Navigation Keys Updated requirements for device implementations that include the Assist action
7.3. Sensors (and subsections) New requirements for some sensor types
7.3.9. High Fidelity Sensors New section with requirements for devices supporting high fidelity sensors
7.3.10.指紋感應器New section on requirements related to fingerprint sensors
7.4.2. IEEE 802.11 (Wi-Fi) Updates regarding support for multicast DNS (mDNS)
7.4.3.藍牙Addition related to Resolvable Private Address (RPA) for Bluetooth Low Energy (BLE)
7.4.4. Near-Field Communications Additions to requirements for Near-Field Communications (NFC)
7.4.5. Minimum Network Capability Added requirements for IPv6 support
7.6.3. Adoptable Storage New section for implementation of adoptable storage
7.7. USB Requirement related to implementing the AOA specification
7.8.3. Near-Ultrasound Additions related to near-ultrasound recording, playback, and audio Relax Near-ultrasound microphone SNR requirement.
8.3. Power-Saving Modes New section with requirements regarding the App Standby and Doze modes
8.4. Power Consumption Accounting New section with requirements for tracking hardware component power usage and attributing that power usage to specific applications
9.1.權限Addition to Permissions requirements
9.7. Kernel Security Features SE Linux updates
9.8.隱私Addition regarding user's consent for access to shared storage over a USB port
9.9. Full-Disk Encryption Requirements related to full disk encryption
9.10. Verified Boot Additional requirement for verified boot
9.11. Keys and Credentials New section of requirements related to keys and credentials
9.12. Data Deletion New section for "Factory Data Reset"
11. Updatable Software Requirement related to the system update policy set by the device owner

13. Contact Us

You can join the android-compatibility forum [Resources, 139 ] and ask for clarifications or bring up any issues that you think the document does not cover.

14. Resources

1. IETF RFC2119 Requirement Levels: http://www.ietf.org/rfc/rfc2119.txt

2. Android Open Source Project: http://source.android.com/

3. Android Television features: http://developer.android.com/reference/android/content/pm/PackageManager.html#FEATURE_LEANBACK

4. Android Watch feature: http://developer.android.com/reference/android/content/res/Configuration.html#UI_MODE_TYPE_WATCH

5. Android UI_MODE_TYPE_CAR API: http://developer.android.com/reference/android/content/res/Configuration.html#UI_MODE_TYPE_CAR

6. API definitions and documentation: http://developer.android.com/reference/packages.html

7. Android Permissions reference: http://developer.android.com/reference/android/Manifest.permission.html

8. android.os.Build reference: http://developer.android.com/reference/android/os/Build.html

9. Android 6.0 allowed version strings: http://source.android.com/docs/compatibility/6.0/versions.html

10. Android Developer Settings: http://developer.android.com/reference/android/provider/Settings.html

11. Telephony Provider: http://developer.android.com/reference/android/provider/Telephony.html

12. Android NDK ABI Management: https://developer.android.com/ndk/guides/abis.html

13. Advanced SIMD architecture: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0388f/Beijfcja.html

14. Android Extension Pack: http://developer.android.com/guide/topics/graphics/opengl.html#aep

15. android.webkit.WebView class: http://developer.android.com/reference/android/webkit/WebView.html

16. WebView compatibility: http://www.chromium.org/

17. HTML5: http://html.spec.whatwg.org/multipage/

18. HTML5 offline capabilities: http://dev.w3.org/html5/spec/Overview.html#offline

19. HTML5 video tag: http://dev.w3.org/html5/spec/Overview.html#video

20. HTML5/W3C geolocation API: http://www.w3.org/TR/geolocation-API/

21. HTML5/W3C webstorage API: http://www.w3.org/TR/webstorage/

22. HTML5/W3C IndexedDB API: http://www.w3.org/TR/IndexedDB/

23. Dalvik Executable Format and bytecode specification: available in the Android source code, at dalvik/docs

24. AppWidgets: http://developer.android.com/guide/practices/ui_guidelines/widget_design.html

25. Notifications: http://developer.android.com/guide/topics/ui/notifiers/notifications.html

26. Application Resources: https://developer.android.com/guide/topics/resources/available-resources.html

27. Status Bar icon style guide: http://developer.android.com/design/style/iconography.html

28. Notifications Resources: https://developer.android.com/design/patterns/notifications.html

29. Search Manager: http://developer.android.com/reference/android/app/SearchManager.html

30. Action Assist: http://developer.android.com/reference/android/content/Intent.html#ACTION_ASSIST

31. Android Assist APIs: https://developer.android.com/reference/android/app/assist/package-summary.html

32. Toasts: http://developer.android.com/reference/android/widget/Toast.html

33. Themes: http://developer.android.com/guide/topics/ui/themes.html

34. R.style class: http://developer.android.com/reference/android/R.style.html

35. Material design: http://developer.android.com/reference/android/R.style.html#Theme_Material

36. Live Wallpapers: http://developer.android.com/reference/android/service/wallpaper/WallpaperService.html

37. Overview screen resources: http://developer.android.com/guide/components/recents.html

38. Screen pinning: https://developer.android.com/about/versions/android-5.0.html#ScreenPinning

39. Input methods: http://developer.android.com/guide/topics/text/creating-input-method.html

40. Media Notification: https://developer.android.com/reference/android/app/Notification.MediaStyle.html

41. Dreams: http://developer.android.com/reference/android/service/dreams/DreamService.html

42. Settings.Secure LOCATION_MODE: http://developer.android.com/reference/android/provider/Settings.Secure.html#LOCATION_MODE

43. Unicode 6.1.0: http://www.unicode.org/versions/Unicode6.1.0/

44. Android Device Administration: http://developer.android.com/guide/topics/admin/device-admin.html

45. DevicePolicyManager reference: http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html

46. Device Owner App: http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#isDeviceOwnerApp(java.lang.String)

47. Android Device Owner Provisioning Flow: http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#ACTION_PROVISION_MANAGED_DEVICE

48. Device Owner Provisioning via NFC: /devices/tech/admin/provision.html#device_owner_provisioning_via_nfc

49. Android Profile Owner App: http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#isProfileOwnerApp(java.lang.String)

50. Android Managed Profile Provisioning flow: http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#ACTION_PROVISION_MANAGED_PROFILE

51. Android Accessibility Service APIs: http://developer.android.com/reference/android/accessibilityservice/AccessibilityService.html

52. Android Accessibility APIs: http://developer.android.com/reference/android/view/accessibility/package-summary.html

53. Eyes Free project: http://code.google.com/p/eyes-free

54. Text-To-Speech APIs: http://developer.android.com/reference/android/speech/tts/package-summary.html

55. Television Input Framework: /devices/tv/index.html

56. TV App channels: http://developer.android.com/reference/android/media/tv/TvContract.Channels.html

57. Third-party TV inputs: /devices/tv/index.html#third-party_input_example

58. TV inputs: /devices/tv/index.html#tv_inputs

59. TV channel EPG fields: https://developer.android.com/reference/android/media/tv/TvContract.Programs.html

60. TV input app linking: http://developer.android.com/reference/android/media/tv/TvContract.Channels.html#COLUMN_APP_LINK_INTENT_URI

61. Reference tool documentation (for adb, aapt, ddms, systrace): http://developer.android.com/tools/help/index.html

62. Android apk file description: http://developer.android.com/guide/components/fundamentals.html

63. Manifest files: http://developer.android.com/guide/topics/manifest/manifest-intro.html

64. Android Media Formats: http://developer.android.com/guide/appendix/media-formats.html

65. Android MediaCodecList API: http://developer.android.com/reference/android/media/MediaCodecList.html

66. Android CamcorderProfile API: http://developer.android.com/reference/android/media/CamcorderProfile.html

67. WebM project: http://www.webmproject.org/

68. RTC Hardware Coding Requirements: http://www.webmproject.org/hardware/rtc-coding-requirements/

69. AudioEffect API: http://developer.android.com/reference/android/media/audiofx/AudioEffect.html

70. Android android.content.pm.PackageManager class and Hardware Features List: http://developer.android.com/reference/android/content/pm/PackageManager.html

71. HTTP Live Streaming Draft Protocol: http://tools.ietf.org/html/draft-pantos-http-live-streaming-03

72. ADB: http://developer.android.com/tools/help/adb.html

73. Dumpsys: /devices/input/diagnostics.html

74. DDMS: http://developer.android.com/tools/debugging/ddms.html

75. Monkey testing tool: http://developer.android.com/tools/help/monkey.html

76. SysyTrace tool: http://developer.android.com/tools/help/systrace.html

77. Android Application Development-Related Settings: http://developer.android.com/reference/android/provider/Settings.html#ACTION_APPLICATION_DEVELOPMENT_SETTINGS

78. Supporting Multiple Screens: http://developer.android.com/guide/practices/screens_support.html

79. android.util.DisplayMetrics: http://developer.android.com/reference/android/util/DisplayMetrics.html

80. RenderScript: http://developer.android.com/guide/topics/renderscript/

81. Android extension pack for OpenGL ES: https://developer.android.com/reference/android/opengl/GLES31Ext.html

82. Hardware Acceleration: http://developer.android.com/guide/topics/graphics/hardware-accel.html

83. EGL Extension-EGL_ANDROID_RECORDABLE: http://www.khronos.org/registry/egl/extensions/ANDROID/EGL_ANDROID_recordable.txt

84. Display Manager: http://developer.android.com/reference/android/hardware/display/DisplayManager.html

85. android.content.res.Configuration: http://developer.android.com/reference/android/content/res/Configuration.html

86. Touch Input Configuration: http://source.android.com/docs/core/interaction/input/touch-devices

87. Motion Event API: http://developer.android.com/reference/android/view/MotionEvent.html

88. Key Event API: http://developer.android.com/reference/android/view/KeyEvent.html

89. Android Open Source sensors: http://source.android.com/docs/core/interaction/sensors

90. android.hardware.SensorEvent: http://developer.android.com/reference/android/hardware/SensorEvent.html

91. Timestamp sensor event: http://developer.android.com/reference/android/hardware/SensorEvent.html#timestamp

92. Android Open Source composite sensors: /docs/core/interaction/sensors/sensor-types#composite_sensor_type_summary

93. Continuous trigger mode: http://developer.android.com/reference/android/hardware/Sensor.html#TYPE_ACCELEROMETER

95. Android Fingerprint API: https://developer.android.com/reference/android/hardware/fingerprint/package-summary.html

96. Android Fingerprint HAL: /devices/tech/security/authentication/fingerprint-hal.html

97. Wi-Fi Multicast API: http://developer.android.com/reference/android/net/wifi/WifiManager.MulticastLock.html

98. Wi-Fi Direct (Wi-Fi P2P): http://developer.android.com/reference/android/net/wifi/p2p/WifiP2pManager.html

99. WifiManager API: http://developer.android.com/reference/android/net/wifi/WifiManager.html

100. Bluetooth API: http://developer.android.com/reference/android/bluetooth/package-summary.html

101. Bluetooth ScanFilter API: https://developer.android.com/reference/android/bluetooth/le/ScanFilter.html

102. NFC Barcode: http://developer.android.com/reference/android/nfc/tech/NfcBarcode.html

103. NDEF Push Protocol: http://source.android.com/docs/compatibility/ndef-push-protocol.pdf

104. Android Beam: http://developer.android.com/guide/topics/connectivity/nfc/nfc.html

105. Android NFC Sharing Settings: http://developer.android.com/reference/android/provider/Settings.html#ACTION_NFCSHARING_SETTINGS

106. NFC Connection Handover: http://members.nfc-forum.org/specs/spec_list/#conn_handover

107. Bluetooth Secure Simple Pairing Using NFC: http://members.nfc-forum.org/apps/group_public/download.php/18688/NFCForum-AD-BTSSP_1_1.pdf

108. Host-based Card Emulation: http://developer.android.com/guide/topics/connectivity/nfc/hce.html

109. Content Resolver: http://developer.android.com/reference/android/content/ContentResolver.html

110. Camera orientation API: http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)

111. Camera: http://developer.android.com/reference/android/hardware/Camera.html

112. Camera: http://developer.android.com/reference/android/hardware/Camera.Parameters.html

113. Camera hardware level: https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics.html#INFO_SUPPORTED_HARDWARE_LEVEL

114. Camera version support: http://source.android.com/docs/core/camera/versioning

115. Android DownloadManager: http://developer.android.com/reference/android/app/DownloadManager.html

116. Android File Transfer: http://www.android.com/filetransfer

117. Adoptable storage: http://source.android.com/docs/core/storage/adoptable

118. Android Open Accessories: http://developer.android.com/guide/topics/connectivity/usb/accessory.html

119. Android USB Audio: http://developer.android.com/reference/android/hardware/usb/UsbConstants.html#USB_CLASS_AUDIO

120. USB Battery Charging Specification, Revision 1.2: http://www.usb.org/developers/docs/devclass_docs/BCv1.2_070312.zip

121. USB Host API: http://developer.android.com/guide/topics/connectivity/usb/host.html

122. Wired audio headset: http://source.android.com/docs/core/interaction/accessories/headset/plug-headset-spec

123. Power profile components: http://source.android.com/docs/core/power/values

124. Batterystats: https://developer.android.com/tools/dumpsys#battery

125. Power usage summary: http://developer.android.com/reference/android/content/Intent.html#ACTION_POWER_USAGE_SUMMARY

126. Android Security and Permissions reference: http://developer.android.com/guide/topics/security/permissions.html

127. UserManager reference: http://developer.android.com/reference/android/os/UserManager.html

128. External Storage reference: http://source.android.com/docs/core/storage/traditional

129. External Storage APIs: http://developer.android.com/reference/android/os/Environment.html

130. SMS Short Code: http://en.wikipedia.org/wiki/Short_code

131. Secure lock screen reporting: http://developer.android.com/reference/android/app/KeyguardManager.html#isDeviceSecure()

132. Android Open Source Encryption: http://source.android.com/docs/security/features/encryption

133. Android Keystore System: https://developer.android.com/training/articles/keystore.html

134. KeyChain API: https://developer.android.com/reference/android/security/KeyChain.html

135. Keystore API: https://developer.android.com/reference/java/security/KeyStore.html

136. Gatekeeper HAL: http://source.android.com/docs/security/features/authentication/gatekeeper

137. Android Compatibility Program Overview: http://source.android.com/docs/compatibility

138. SystemUpdatePolicy class: http://developer.android.com/reference/android/app/admin/SystemUpdatePolicy.html

139. Android Compatibility forum: https://groups.google.com/forum/#!forum/android-compatibility

140. Handling app links: https://developer.android.com/training/app-links/index.html

141. Google Digital Asset Links: https://developers.google.com/digital-asset-links

Many of these resources are derived directly or indirectly from the Android SDK, and will be functionally identical to the information in that SDK's documentation. In any cases where this Compatibility Definition or the Compatibility Test Suite disagrees with the SDK documentation, the SDK documentation is considered authoritative. Any technical details provided in the references included above are considered by inclusion to be part of this Compatibility Definition.