Android 12(SDK 31)触发ForegroundServiceStartNotAllowedException如何解决？

问题背景 #

将应用的targetSdkVersion和compileSdkVersion升级到SDK 31后，在用于后台更新小组件的服务中会出现如下崩溃：

java.lang.RuntimeException: 
  at android.app.ActivityThread.handleReceiver (ActivityThread.java:4321)
  at android.app.ActivityThread.access$1600 (ActivityThread.java:247)
  at android.app.ActivityThread$H.handleMessage (ActivityThread.java:2068)
  at android.os.Handler.dispatchMessage (Handler.java:106)
  at android.os.Looper.loopOnce (Looper.java:201)
  at android.os.Looper.loop (Looper.java:288)
  at android.app.ActivityThread.main (ActivityThread.java:7842)
  at java.lang.reflect.Method.invoke (Native Method)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:548)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1003)
Caused by: android.app.ForegroundServiceStartNotAllowedException: 
  at android.app.ForegroundServiceStartNotAllowedException$1.createFromParcel (ForegroundServiceStartNotAllowedException.java:54)
  at android.app.ForegroundServiceStartNotAllowedException$1.createFromParcel (ForegroundServiceStartNotAllowedException.java:50)
  at android.os.Parcel.readParcelable (Parcel.java:3333)
  at android.os.Parcel.createExceptionOrNull (Parcel.java:2420)
  at android.os.Parcel.createException (Parcel.java:2409)
  at android.os.Parcel.readException (Parcel.java:2392)
  at android.os.Parcel.readException (Parcel.java:2334)
  at android.app.IActivityManager$Stub$Proxy.startService (IActivityManager.java:5971)
  at android.app.ContextImpl.startServiceCommon (ContextImpl.java:1847)
  at android.app.ContextImpl.startForegroundService (ContextImpl.java:1823)
  at android.content.ContextWrapper.startForegroundService (ContextWrapper.java:779)
  at android.content.ContextWrapper.startForegroundService (ContextWrapper.java:779)
  at com.mypackage.appname.ui.widget.widget_package.WidgetClassName.onUpdate (WidgetClassName.java:48)
  at android.appwidget.AppWidgetProvider.onReceive (AppWidgetProvider.java:66)
  at com.mypackage.appname.ui.widget.widget_package.WidgetClassName.onReceive (WidgetClassName.java)
  at android.app.ActivityThread.handleReceiver (ActivityThread.java:4312)
  at android.app.ActivityThread.access$1600 (ActivityThread.java:247)
  at android.app.ActivityThread$H.handleMessage (ActivityThread.java:2068)
  at android.os.Handler.dispatchMessage (Handler.java:106)
  at android.os.Looper.loopOnce (Looper.java:201)
  at android.os.Looper.loop (Looper.java:288)
  at android.app.ActivityThread.main (ActivityThread.java:7842)
  at java.lang.reflect.Method.invoke (Native Method)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:548)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1003)
Caused by: android.os.RemoteException: 
  at com.android.server.am.ActiveServices.startServiceLocked (ActiveServices.java:691)
  at com.android.server.am.ActiveServices.startServiceLocked (ActiveServices.java:616)
  at com.android.server.am.ActivityManagerService.startService (ActivityManagerService.java:11839)
  at android.app.IActivityManager$Stub.onTransact (IActivityManager.java:2519)
  at com.android.server.am.ActivityManagerService.onTransact (ActivityManagerService.java:2498)

如果你使用Firebase Crashlytics这类崩溃采集工具，收到的堆栈信息将类似如下：

Caused by android.app.ForegroundServiceStartNotAllowedException: startForegroundService() not allowed due to mAllowStartForeground false: service com.mypackage.appname/.ui.widget.widget_package.MyForegroundServiceName
       at android.app.ForegroundServiceStartNotAllowedException$1.createFromParcel(ForegroundServiceStartNotAllowedException.java:54)
       at android.app.ForegroundServiceStartNotAllowedException$1.createFromParcel(ForegroundServiceStartNotAllowedException.java:50)
       at android.os.Parcel.readParcelable(Parcel.java:3333)
       at android.os.Parcel.createExceptionOrNull(Parcel.java:2420)
       at android.os.Parcel.createException(Parcel.java:2409)
       at android.os.Parcel.readException(Parcel.java:2392)
       at android.os.Parcel.readException(Parcel.java:2334)
       at android.app.IActivityManager$Stub$Proxy.startService(IActivityManager.java:5971)
       at android.app.ContextImpl.startServiceCommon(ContextImpl.java:1847)
       at android.app.ContextImpl.startForegroundService(ContextImpl.java:1823)
       at android.content.ContextWrapper.startForegroundService(ContextWrapper.java:779)
       at android.content.ContextWrapper.startForegroundService(ContextWrapper.java:779)
       at com.mypackage.appname.ui.widget.widget_package.WidgetClassName.onUpdate(WidgetClassName.java:48)
       at android.appwidget.AppWidgetProvider.onReceive(AppWidgetProvider.java:66)
       at com.mypackage.appname.ui.widget.widget_package.WidgetClassName.onReceive(WidgetClassName.java)
       at android.app.ActivityThread.handleReceiver(ActivityThread.java:4312)
       at android.app.ActivityThread.access$1600(ActivityThread.java:247)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2068)
       at android.os.Handler.dispatchMessage(Handler.java:106)
       at android.os.Looper.loopOnce(Looper.java:201)
       at android.os.Looper.loop(Looper.java:288)
       at android.app.ActivityThread.main(ActivityThread.java:7842)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)

根因说明 #

Android 12（API 31）新增了前台服务启动限制，系统仅允许应用在处于特定前台场景、或被加入临时白名单的情况下启动前台服务。而AppWidgetProvider.onUpdate属于普通广播回调，不会将应用加入允许启动前台服务的临时白名单，当应用处于后台时触发该回调、并调用startForegroundService()就会抛出ForegroundServiceStartNotAllowedException。

复现方法 #

• 把应用的targetSdkVersion和compileSdkVersion升级到31及以上
• 在AppWidgetProvider.onUpdate()回调中直接调用startForegroundService()启动前台服务
• 将应用退到后台，触发小组件更新（可通过调整小组件刷新周期、或系统自动触发更新）
• 即可复现该崩溃

修复方案 #

方案1：使用WorkManager替代前台服务（推荐） #

小组件更新通常是耗时较短的后台任务，使用Jetpack WorkManager调度任务可以完全规避前台服务启动限制，适配所有Android版本。
示例代码如下：

// 定义执行小组件更新的Worker
class WidgetUpdateWorker(private val context: Context, params: WorkerParameters) : Worker(context, params) {
    override fun doWork(): Result {
        // 把原来放在前台服务里的小组件更新逻辑移到这里执行
        val appWidgetManager = AppWidgetManager.getInstance(context)
        val appWidgetIds = appWidgetManager.getAppWidgetIds(ComponentName(context, WidgetClassName::class.java))
        appWidgetIds.forEach { widgetId ->
            // 执行单组件更新逻辑
            updateSingleWidget(widgetId)
        }
        return Result.success()
    }

    private fun updateSingleWidget(widgetId: Int) {
        // 你的自定义更新逻辑
    }
}

// 在Widget的onUpdate回调中触发任务
override fun onUpdate(context: Context, appWidgetManager: AppWidgetManager, appWidgetIds: IntArray) {
    val updateRequest = OneTimeWorkRequestBuilder<WidgetUpdateWorker>()
        .build()
    WorkManager.getInstance(context).enqueue(updateRequest)
}

方案2：场景适配，仅前台状态启动前台服务 #

如果你的业务必须使用前台服务，可以在启动前先判断应用当前的前后台状态，仅前台状态下启动前台服务，后台状态下降级为WorkManager调度。

private boolean isAppOnForeground(Context context) {
    ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
    List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
    if (appProcesses == null) {
        return false;
    }
    final String packageName = context.getPackageName();
    for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
        if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND && appProcess.processName.equals(packageName)) {
            return true;
        }
    }
    return false;
}

// 调用处逻辑
if (isAppOnForeground(context)) {
    // 应用在前台，正常启动前台服务
    context.startForegroundService(new Intent(context, MyForegroundService.class));
} else {
    // 后台状态使用WorkManager执行任务
    OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(WidgetUpdateWorker.class).build();
    WorkManager.getInstance(context).enqueue(workRequest);
}

方案3：申请特殊前台服务权限（不推荐） #

如果业务必须在后台启动前台服务，可以在AndroidManifest.xml中声明特殊权限：

<uses-permission android:name="android.permission.FOREGROUND_SERVICE_SPECIAL_USE" />
<service
    android:name=".ui.widget.widget_package.MyForegroundServiceName"
    android:foregroundServiceType="specialUse"
    android:exported="false">
</service>

该方案需要应用启动时引导用户手动开启"允许特殊前台服务"权限，且Google Play上架时需要提供合理的使用说明，不符合要求的应用会被驳回。 #

内容的提问来源于stack exchange，提问作者Vedprakash Wagh