当最新任务列表中的应用被杀死时，Android后台服务永远不会启动

Question

I want to create a never ending background service in Android. To do this I am using AlarmManager with Simple Service Alarmmanger send broadcast after some interval ,In broadcast Receiver I'm checking wether the service is running, if running then do nothing else start it again .

My service code is

public class MyService extends Service {
    public MyService() {
    }

    @Override
    public IBinder onBind(Intent intent) {
           return null;
    }
    @Override
    public void onCreate() {
        super.onCreate ( );
        Log.e ("My service ", "oncreate");
    }

    @Override
    public void onTaskRemoved(Intent rootIntent) {
        scheduleAlarm ();
        super.onTaskRemoved (rootIntent);
    }
     // Setup a recurring alarm every half hour
    public void scheduleAlarm() {
        // Construct an intent that will execute the ServiceAlarmReceiver
        Intent intent = new Intent("com.hmkcode.android.USER_ACTION");
        // Create a PendingIntent to be triggered when the alarm goes off
        final PendingIntent pIntent = PendingIntent.getBroadcast(this, ServiceReceiver.REQUEST_CODE,
                intent, PendingIntent.FLAG_UPDATE_CURRENT);
        // Setup periodic alarm every 5 seconds
        long firstMillis = System.currentTimeMillis()+5000; // alarm is set right away
        AlarmManager alarm = (AlarmManager) this.getSystemService(Context.ALARM_SERVICE);
        // First parameter is the type: ELAPSED_REALTIME, ELAPSED_REALTIME_WAKEUP, RTCWAKEUP
        // Interval can be INTERVAL_FIFTEEN_MINUTES, INTERVAL_HALF_HOUR, INTERVAL_HOUR, INTERVAL_DAY
        alarm.setInexactRepeating(AlarmManager.RTC_WAKEUP, firstMillis,
                6000, pIntent);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

         Log.e ("My Service:", " on Start Command");
          return START_STICKY;
    }
 }

Broadcast Receiver

public class ServiceReceiver extends WakefulBroadcastReceiver {

    public static final int REQUEST_CODE=12355;
    public ServiceReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
        // an Intent broadcast.
        // check service  is running or not
        if (isMyServiceRunning (MessageService.class,context)){
            // don nothing

        }
        else {
            // launch the service
            if (isConnectedToInternet (context)) {
                Intent serviceIntent = new Intent (context, MyService.class);
                context.startService (serviceIntent);
            }
        }


        Log.e ("hello","wer are in Receiver" );
       // throw new UnsupportedOperationException ("Not yet implemented");
    }
}

My Manifest:

 <receiver
            android:name=".Services.ServiceReceiver"
            android:enabled="true"
            android:exported="true"
            android:process=":remote">

            <intent-filter>
                <action android:name="com.hmkcode.android.USER_ACTION" />
            </intent-filter>
        </receiver>

        <service
            android:name=".Services.MyService"
            android:enabled="true"
            android:stopWithTask="false"
            android:process=":remote"

        >
        </service>

It worked fine when the app is in foreground or in background but the problem is when I swipe out the app from recent Task list in Android, the app got killed so as the service and My broadcast Receiver never able to start it again? I am rescheduling my Alarmmanger in onTaskRemoved Method, but still the service is not starting again.

Also Return START_STICKY from onStartCommand() as people said With this, system will re-start the service even if it has to be stopped for resources limitations.

Also used "stopWithTask"=false in <service> tag of manifest file. It also had no impact.

Answer 1

I've had success with creating a PendingIntent through the alarm manager and instantiating it through code instead of declaratively.

public class HeartbeatReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        try{
            Log.i(MainService.TAG, "** Heartbeat onReceive **");
            if (!Utility.isMyServiceRunning(context)){
                Log.i(MainService.TAG, "Service is dead. Restarting...");
                context.startService(new Intent(context, MainService.class));
                return;
            }
        }
    }

    public void StartHeartbeat(Context context, int interval) {
        this.CancelHeartbeat(context);
        AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
        Intent i = new Intent(context, HeartbeatReceiver.class);
        PendingIntent pi = PendingIntent.getBroadcast(context, 0, i, 0);
        am.setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), interval, pi);
    }

    public void CancelHeartbeat(Context context) {
        Intent intent = new Intent(context, HeartbeatReceiver.class);
        PendingIntent sender = PendingIntent.getBroadcast(context, 0, intent, 0);
        AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
        alarmManager.cancel(sender);
    }
}

I initialize the receiver programmatically in the Application class. It didn't seem to work when the intent was created in the manifest.

public class MainApp extends Application {
    @Override
    public void onCreate(){
        super.onCreate();
        MainService.baseContext = getBaseContext();
        HeartbeatReceiver heartBeat = new HeartbeatReceiver();
        heartBeat.StartHeartbeat(MainService.baseContext, 60 * 1000 * 5);

    }
}

Then just the receiver in the manifest with no intent

 <receiver android:name="HeartbeatReceiver"/>

This was the result of experimenting so I'm not exactly sure why it works but if I kill the app it comes back successfully when the next alarm runs. Hope that helps.