問題現象：
App出現異常： java.lang.IllegalStateException: Not allowed to start service Intent xxxx app is in background uid UidRecord
App直接崩潰。
問題原因：
App targetSdkVersion>= 26的情況下，用戶允許App開機自啓動，App被殺死或者系統重啓後，系統直接將App後臺啓動起來，App在後臺啓動的過程中有使用startService()方法。
Google在Android 8.0之後對於處於後臺的App啓動Service進行了嚴格的限制，不再允許後臺App啓動後臺Service，如果使用會直接拋出異常。
問題調研：
- 微信：反編譯App後，沒有找到對應Service的代碼，懷疑可能是熱加載的
- QQ：目前targetSdkVersion = 23，不存在此問題
- 小天才：使用startForegroundService方法，Notification設置channel爲null，狀態欄不顯示通知
- 360兒童衛士：使用startForegroundService方法，Notification正常設置，狀態欄顯示通知
解決方法：
使用startForegroundService，此方法會在狀態欄顯示通知
// 啓動服務的地方
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
context.startForegroundService(new Intent(context, MyService.class));
} else {
context.startService(new Intent(context, MyService.class));
}
// 在MyService中
@Override
public void onCreate() {
super.onCreate();
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
NotificationChannel channel = null;
channel = new NotificationChannel(CHANNEL_ID_STRING, getString(R.string.app_name), NotificationManager.IMPORTANCE_HIGH);
notificationManager.createNotificationChannel(channel);
Notification notification = new Notification.Builder(getApplicationContext(), CHANNEL_ID_STRING).build();
startForeground(1, notification);
}
}
去除狀態欄方法
stopForeground()
//在 startForeground(1, notification);後添加如下代碼，取消前臺服務
myHandler.postDelayed(new Runnable() {
@Override
public void run() {
stopForeground(true);
}
}, 1000);
channel 設置爲null，此方法只適用於targetSdkVersion = 26的情況
Notification.Builder builder = new Notification.Builder(this, null)
.setContentTitle(getString(R.string.app_name))
.setContentText("")
.setAutoCancel(true);
Notification notification = builder.build();
startForeground(1, notification);
對於去除通知的第2種方法，源碼查看：
final class ServiceRecord extends Binder implements ComponentName.WithComponentName {
public void postNotification() {
if (foregroundId != 0 && foregroundNoti != null) {
...
ams.mHandler.post(new Runnable() {
public void run() {
NotificationManagerInternal nm = LocalServices.getService(NotificationManagerInternal.class);
if (nm == null) {
return;
}
Notification localForegroundNoti = _foregroundNoti;
try {
if (localForegroundNoti.getSmallIcon() == null) {
...//沒有smallIcon進行處理
}
if (nm.getNotificationChannel(localPackageName, appUid, localForegroundNoti.getChannelId()) == null) {
int targetSdkVersion = Build.VERSION_CODES.O_MR1;
try {
final ApplicationInfo applicationInfo = ams.mContext.getPackageManager().getApplicationInfoAsUser(appInfo.packageName, 0, userId);
targetSdkVersion = applicationInfo.targetSdkVersion;
} catch (PackageManager.NameNotFoundException e) {
}
if (targetSdkVersion >= Build.VERSION_CODES.O_MR1) {
throw new RuntimeException("invalid channel for service notification: " + foregroundNoti);
}
}
nm.enqueueNotification(localPackageName, localPackageName, appUid, appPid, null, localForegroundId, localForegroundNoti, userId);
foregroundNoti = localForegroundNoti; // save it for amending next time
} catch (RuntimeException e) {
Slog.w(TAG, "Error showing notification for service", e);
// If it gave us a garbage notification, it doesn't
// get to be foreground.
ams.setServiceForeground(name, ServiceRecord.this, 0, null, 0);
ams.crashApplication(appUid, appPid, localPackageName, -1, "Bad notification for startForeground: " + e);
}
}
});
}
}
}
從源碼中可以看出，在發送通知檢查時，如果targetSdkVersion >= Build.VERSION_CODES.O_MR1即targetSdkVersion >= 27時，如果設置channel爲null纔會拋出RuntimeException，crash當前App。
對於targetSdkVersion = 26的app會捕獲異常，正常將notification加入隊列，但此notification並不會進行顯示。