行為變更：所有應用程式

Android 17 平台包含可能對應用程式造成影響的行為變更。無論 targetSdkVersion 為何，凡是在 Android 17 上執行的應用程式，「一律」都會受到下列行為變更所影響。您必須測試自己的應用程式，並視需要進行修改，以便在適當情況下支援這些變更。

另請務必查看僅對指定 Android 17 為目標版本的應用程式造成影響的行為變更。

核心功能

Android 17 (API 級別 37) 包含下列異動項目，這類變更會修改或擴充 Android 系統的各種核心功能。

應用程式記憶體限制

Android 17 introduces app memory limits based on the device's total RAM to create a more stable and deterministic environment for your apps and Android users. In Android 17, limits are set conservatively to establish system baselines, targeting extreme memory leaks and other outliers before they trigger system-wide instability resulting in UI stuttering, higher battery drain, and apps being killed. While we anticipate minimal impact on the vast majority of app sessions, we recommend the following memory best practices, including establishing a baseline for memory.

You can determine if your app session was impacted by calling getDescription in ApplicationExitInfo; if your app was affected, the exit reason will be REASON_OTHER and the description will contain the string "MemoryLimiter:AnonSwap" along with other information. You can also use trigger-based profiling with TRIGGER_TYPE_ANOMALY to get heap dumps that are collected when the memory limit is hit.

The Manage your app's memory documentation gives information to help you diagnose your app's memory issues and optimize its resource consumption.

Test your app's behavior under the memory constraints

You can use Android Debug Bridge (adb) to adjust or disable the memory limits on any device that imposes them. The shell command am provides three subcommands to adjust the memory limits. (These commands have no effect on a device which does not impose memory limits.)

  • am memory-limiter ignore <uid>|none|all
  • am memory-limiter manual <pid> <limit>|max|none
  • am memory-limiter status
ignore

Instructs the memory limiter to ignore some or all processes. Passing a UID (Android User ID) instructs the memory limiter to ignore enforcement on all processes associated with that UID. You can also pass all (ignore all apps) or none (do not ignore any apps). Passing none overrides any previous calls to am memory-limiter ignore.

If you instruct the memory limiter to ignore a UID, you can still apply a manual memory limit to a process within the app by calling am memory-limiter manual.

manual

Instructs the system to impose a memory constraint on the process with the specified PID (Process ID). The memory constraint is specified as an integer number of MB; for example, passing 30 specifies that the process is limited to 30 MB of memory. Passing max removes all memory limits on that process. Passing none removes any manual limits set on the process, restoring the system's default limit (if any).

status

Reports the current status of the memory limiter. The status includes the memory limits imposed on visible and non-visible processes.

隱私權

Android 17 包含下列異動項目，可提升使用者隱私權。

簡訊動態密碼防護

Beginning with Android 17, Android is expanding its protection for SMS messages containing one-time passwords (OTP).

In previous versions of Android, this protection was primarily focused on the SMS Retriever format. Delivery of messages containing an SMS retriever hash was delayed for most apps for three hours. However, certain apps (like the default SMS handler) were exempt from the delay, and the app that owned the hash was also exempted.

Beginning with Android 17, the protection is also applied to WebOTP format messages. If an app has permission to read SMS messages but is not the intended recipient of a WebOTP message (as determined by domain verification), the message is not accessible to the app until three hours after the message's receipt. This change is intended to improve user security by ensuring that only apps associated with the domain mentioned in the message can programmatically read the verification code.

During this three hour delay, the SMS_RECEIVED_ACTION broadcast is withheld and SMS provider database queries are filtered. The SMS message is available to these apps after the delay. This change applies to all apps, regardless of their target API level.

Certain apps such as the default SMS assistant app, connected device companion apps, etc., are exempted from this delay. All apps that rely on reading SMS messages for OTP extraction should transition to using SMS Retriever or SMS User Consent APIs to ensure continued functionality.

安全性

Android 17 包含下列裝置和應用程式安全防護改善項目。

usesClearTraffic 淘汰計畫

In a future release, we plan to deprecate the usesCleartextTraffic element. Apps that need to make unencrypted (HTTP) connections should migrate to using a network security configuration file, which lets you specify which domains your app needs to make cleartext connections to.

Be aware that network security configuration files are only supported on API levels 24 and higher. If your app has a minimum API level lower than 24, you should do both of the following:

  • Set the usesCleartextTraffic attribute to true
  • Use a network configuration file

If your app's minimum API level is 24 or higher, you can use a network configuration file and you don't need to set usesCleartextTraffic.

限制隱含 URI 授權

目前，如果應用程式啟動的意圖含有 URI，且動作為 ACTION_SEND、ACTION_SEND_MULTIPLE 或 ACTION_IMAGE_CAPTURE，系統會自動授予目標應用程式 URI 讀取和寫入權限。但從 Android 18 開始，系統將不再自動授予這些權限。因此，建議應用程式明確授予相關 URI 權限，而非依賴系統授予。

如要在應用程式中偵測這些意圖的使用情形，請搭配使用 StrictMode 和 detectImplicitUriPermissionGrant()，觸發違規行為：

Kotlin

val policy = StrictMode.VmPolicy.Builder()
    .detectImplicitUriPermissionGrant()
    .penaltyLog()
    .build()
StrictMode.setVmPolicy(policy)

Java

StrictMode.VmPolicy policy = new StrictMode.VmPolicy.Builder()
    .detectImplicitUriPermissionGrant()
    .penaltyLog()
    .build();
StrictMode.setVmPolicy(policy);

或者，您也可以監控包含訊息 Please set the grant explicitly in the app 的已記錄例外狀況，這類訊息會在系統隱含設定授權時顯示。您可以使用下列 adb 指令監控這些記錄：

adb logcat | grep "Please set the grant explicitly in the app"

如要明確授予必要權限，請將 FLAG_GRANT_READ_URI_PERMISSION 標記新增至 ACTION_SEND 和 ACTION_SEND_MULTIPLE 意圖：

Kotlin

intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)

Java

intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);

針對 ACTION_IMAGE_CAPTURE 意圖，同時加入 FLAG_GRANT_READ_URI_PERMISSION 和 FLAG_GRANT_WRITE_URI_PERMISSION 旗標：

Kotlin

intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION)

Java

intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);

每個應用程式的 Keystore 限制

Apps should avoid creating excessive numbers of keys in Android Keystore, because it is a shared resource for all apps on the device. Beginning with Android 17, the system enforces a limit on the number of keys an app can own. The limit is 50,000 keys for non-system apps targeting Android 17 (API level 37) or higher, and 200,000 keys for all other apps. System apps have a limit of 200,000 keys, regardless of which API level they target.

If an app attempts to create keys beyond the limit, the creation fails with a KeyStoreException. The exception's message string contains information about the key limit. If the app calls getNumericErrorCode() on the exception, the return value depends on what API level the app targets:

  • Apps targeting Android 17 (API level 37) or higher: getNumericErrorCode() returns the new ERROR_TOO_MANY_KEYS value.
  • All other apps: getNumericErrorCode() returns ERROR_INCORRECT_USAGE.

封鎖跨設定檔迴路流量

从 Android 17 开始，默认情况下不再允许跨个人资料环回流量。同一个人资料内的环回流量不受影响。 此项变更适用于在 Android 17 或更高版本上运行的所有应用，无论应用以哪个 API 级别为目标平台。

使用者體驗和系統 UI

Android 17 包含下列變更，目的是為了打造更一致、直覺的使用者體驗。

裝置旋轉後自動恢復預設的 IME 版面空間

Beginning with Android 17, when the device's configuration changes (for example, through rotation), and this is not handled by the app itself, the previous IME visibility is not restored.

If your app undergoes a configuration change that it does not handle, and the app needs the keyboard to be visible after the change, you must explicitly request this. You can make this request in one of the following ways:

  • Set the android:windowSoftInputMode attribute to stateAlwaysVisible.
  • Programmatically request the soft keyboard in your activity's onCreate() method, or add the onConfigurationChanged() method.

手動輸入

Android 17 包含下列異動項目，這些變更會影響應用程式與鍵盤和觸控板等人工輸入裝置的互動方式。

在指標擷取期間，觸控板預設會傳送相對事件

Beginning with Android 17, if an app requests pointer capture using View.requestPointerCapture() and the user uses a touchpad, the system recognizes pointer movement and scrolling gestures from the user's touches and reports them to the app in the same way as pointer and scroll wheel movements from a captured mouse. In most cases, this removes the need for apps that support captured mice to add special handling logic for touchpads. For more details, see the documentation for View.POINTER_CAPTURE_MODE_RELATIVE.

Previously, the system did not attempt to recognize gestures from the touchpad, and instead delivered the raw, absolute finger locations to the app in a similar format to touchscreen touches. If an app still requires this absolute data, it should call the new View.requestPointerCapture(int) method with View.POINTER_CAPTURE_MODE_ABSOLUTE instead.

媒體

Android 17 包含下列媒體行為變更。

背景音訊強化

Beginning with Android 17, the audio framework enforces restrictions on background audio interactions including audio playback, audio focus requests, and volume change APIs to ensure that these changes are started intentionally by the user.

If the app tries to call audio APIs while the app is not in a valid lifecycle, the audio playback and volume change APIs fail silently without throwing an exception or providing a failure message. The audio focus API fails with the result code AUDIOFOCUS_REQUEST_FAILED.

For more information, including mitigation strategies, see Background audio hardening.

連線能力

Android 17 包含下列異動項目，可提升裝置連線能力。

藍牙配對遺失時自動重新配對

Android 17 推出自主重新配對連線功能，這項系統層級的強化功能旨在自動解決藍牙連線中斷問題。

以往，如果連線遺失，使用者必須手動前往「設定」取消配對，然後重新配對周邊裝置。這項功能以 Android 16 的安全性提升為基礎，可讓系統在背景重新建立連線，使用者不必手動前往「設定」解除配對並重新配對周邊裝置。

雖然大多數應用程式不需要變更程式碼，但開發人員應留意藍牙堆疊的下列行為變更：

  • 新的配對情境：ACTION_PAIRING_REQUEST 現在包含 EXTRA_PAIRING_CONTEXT 額外內容，可讓應用程式區分標準配對要求，以及自主系統啟動的重新配對嘗試。
  • 有條件的金鑰更新：只有在重新配對成功，且新連線達到或超過先前連結的安全等級時，現有的安全金鑰才會遭到取代。
  • 修改意圖時間：現在只有在自主重新配對嘗試失敗時，才會廣播 ACTION_KEY_MISSING 意圖。如果系統在背景成功復原連線，應用程式就不必進行不必要的錯誤處理。
  • 使用者通知：系統會透過新的 UI 通知和對話方塊管理重新配對作業。系統會提示使用者確認重新配對嘗試，確保他們知道裝置要重新連線。

周邊裝置製造商和隨附應用程式開發人員應確認硬體和應用程式能妥善處理配對轉換。如要測試這項行為，請使用下列任一方法模擬遠端連結遺失：

  • 手動從周邊裝置移除配對資訊
  • 手動取消配對裝置：依序前往「設定」>「已連結的裝置」