Android 14 平台包含一些行为变更,这些变更可能会影响您的应用。以下行为变更将影响在 Android 14 上运行的所有应用,无论采用哪种 targetSdkVersion
都不例外。您应该测试您的应用,然后根据需要进行修改,以适当地支持这些变更。
此外,请务必查看仅影响以 Android 14 为目标平台的应用的行为变更列表。
核心功能
默认拒绝设定精确的闹钟
精确的闹钟适用于用户指定的通知,或是在确切时间需要执行的操作。从 Android 14 开始,系统不再向以 Android 13 及更高版本为目标平台的大多数新安装应用预先授予 SCHEDULE_EXACT_ALARM
权限,该权限默认处于拒绝状态。
详细了解安排精确闹钟的权限变化。
当应用进入缓存时,上下文注册的广播将加入队列
在 Android 14 中,当应用处于缓存状态时,系统可以将上下文注册的广播放入队列中。这与 Android 12(API 级别 31)为异步 binder 事务引入的队列行为类似。在清单中声明的广播不会加入队列,并且应用会从缓存状态中移除以进行广播传递。
当应用离开缓存状态(例如返回前台)时,系统会传递所有已加入队列的广播。某些广播的多个实例 可能会合并为一个广播。取决于其他因素,如系统 运行状况,则可能会从缓存状态中移除应用,以及之前排队 广播。
应用只能终止自己的后台进程
Starting in Android 14, when your app calls killBackgroundProcesses()
,
the API can kill only the background processes of your own app.
If you pass in the package name of another app, this method has no effect on that app's background processes, and the following message appears in Logcat:
Invalid packageName: com.example.anotherapp
Your app shouldn't use the killBackgroundProcesses()
API or otherwise attempt
to influence the process lifecycle of other apps, even on older OS versions.
Android is designed to keep cached apps in the background and kill them
automatically when the system needs memory. If your app kills other apps
unnecessarily, it can reduce system performance and increase battery consumption
by requiring full restarts of those apps later, which takes significantly more
resources than resuming an existing cached app.
为请求 MTU 的第一个 GATT 客户端将 MTU 设置为 517
Starting from Android 14, the Android Bluetooth stack more strictly adheres to
Version 5.2 of the Bluetooth Core Specification and requests
the BLE ATT MTU to 517 bytes when the first GATT client requests an MTU using
the BluetoothGatt#requestMtu(int)
API, and disregards all subsequent MTU
requests on that ACL connection.
To address this change and make your app more robust, consider the following options:
- Your peripheral device should respond to the Android device's MTU request
with a reasonable value that can be accommodated by the peripheral. The
final negotiated value will be a minimum of the Android requested value and
the remote provided value (for example,
min(517, remoteMtu)
)- Implementing this fix could require a firmware update for peripheral
- Alternatively, limit your GATT characteristic writes based on the minimum
between the known supported value of your peripheral and the received MTU
change
- A reminder that you should reduce 5 bytes from the supported size for the headers
- For example:
arrayMaxLength = min(SUPPORTED_MTU, GATT_MAX_ATTR_LEN(517)) - 5
应用被放入受限待机模式存储分区的新原因
Android 14 引入了一种可将应用放入受限待机模式存储分区的新原因。由于 onStartJob
、onStopJob
或 onBind
方法超时,应用的作业多次触发 ANR 错误。(如需了解对 onStartJob
和 onStopJob
的更改,请参阅 JobScheduler 强化了回调和网络行为。)
如需跟踪应用是否已进入受限待机分桶,我们建议您在作业执行时使用 API UsageStatsManager.getAppStandbyBucket()
进行日志记录,或在应用启动时使用 UsageStatsManager.queryEventsForSelf()
进行日志记录。
mlock 限制为 64 KB
在 Android 14(API 级别 34)及更高版本中,平台将可使用 mlock()
锁定的最大内存量减少到每个进程 64 KB。在之前的版本中,每个进程的上限为 64 MB。此限制有助于更好地管理应用和系统的内存。为了在各种设备上提供更一致的体验,Android 14 针对兼容设备上的新 mlock()
限制添加了一项新的 CTS 测试。
系统强制执行缓存应用资源用量
By design, an app's process is in a cached state when it's moved to the
background and no other app process components are running. Such an app process
is subject to being killed due to system memory pressure. Any work that
Activity
instances perform after the onStop()
method has been called and
returned, while in this state, is unreliable and strongly discouraged.
Android 14 introduces consistency and enforcement to this design. Shortly after an app process enters a cached state, background work is disallowed, until a process component re-enters an active state of the lifecycle.
Apps that use typical framework-supported lifecycle APIs – such as
services, JobScheduler
, and Jetpack WorkManager – shouldn't be
impacted by these changes.
用户体验
关于不可关闭通知用户体验方式的变更
If your app shows non-dismissable foreground notifications to users, Android 14 has changed the behavior to allow users to dismiss such notifications.
This change applies to apps that prevent users from dismissing foreground
notifications by setting Notification.FLAG_ONGOING_EVENT
through
Notification.Builder#setOngoing(true)
or
NotificationCompat.Builder#setOngoing(true)
. The behavior of
FLAG_ONGOING_EVENT
has changed to make such notifications actually
dismissable by the user.
These kinds of notifications are still non-dismissable in the following conditions:
- When the phone is locked
- If the user selects a Clear all notification action (which helps with accidental dismissals)
Also, this new behavior doesn't apply to notifications in the following use cases:
CallStyle
notifications- Device policy controller (DPC) and supporting packages for enterprise
- Media notifications
- The default Search Selector package
数据安全信息更显眼
为了加强用户隐私保护,Android 14 增加了系统显示您在 Play 管理中心表单中声明的信息的位置数量。目前,用户可以在 Google Play 中的应用详情的数据安全部分查看此信息。
我们建议您查看应用的位置数据分享政策,并花一点时间对应用的 Google Play“数据安全”部分进行任何适用的更新。
如需了解详情,请参阅有关如何在 Android 14 上以更显眼的方式显示数据安全信息的指南。
无障碍
非线性字体放大至 200%
从 Android 14 开始,系统支持字体放大高达 200%,为弱视用户提供了符合网络内容无障碍指南 (WCAG) 的其他无障碍功能选项。
如果您已使用放大像素 (sp) 单位来定义文本大小,这项更改可能不会对您的应用产生太大影响。不过,您应在启用最大字号 (200%) 的情况下执行界面测试,确保应用能够在不影响易用性的情况下适应较大的字号。
安全
最低可安装的目标 API 级别
Starting with Android 14, apps with a
targetSdkVersion
lower than 23
can't be installed. Requiring apps to meet these minimum target API level
requirements improves security and privacy for users.
Malware often targets older API levels in order to bypass security and privacy
protections that have been introduced in newer Android versions. For example,
some malware apps use a targetSdkVersion
of 22 to avoid being subjected to the
runtime permission model introduced in 2015 by Android 6.0 Marshmallow (API
level 23). This Android 14 change makes it harder for malware to avoid security
and privacy improvements.
Attempting to install an app targeting a lower API level will result in an
installation failure, with the following message appearing in Logcat:
INSTALL_FAILED_DEPRECATED_SDK_VERSION: App package must target at least SDK version 23, but found 7
On devices upgrading to Android 14, any apps with a targetSdkVersion
lower
than 23 will remain installed.
If you need to test an app targeting an older API level, use the following ADB command:
adb install --bypass-low-target-sdk-block FILENAME.apk
媒体所有者软件包名称可能会隐去
媒体库支持查询 OWNER_PACKAGE_NAME
列,该列表示存储特定媒体文件的应用。从 Android 14 开始,除非满足以下条件之一,否则系统会隐去此值:
- 存储媒体文件的应用有一个软件包名称始终对其他应用可见。
查询媒体库的应用会请求
QUERY_ALL_PACKAGES
权限。
详细了解 Android 如何出于隐私保护目的而过滤软件包可见性。