java - 为什么我的后台服务或我的广播接收器被主要 Activity 杀死？

Question

我想要像 Pushbullet、SmartLockScreen 或 WhatsApp 那样独立运行的服务，它正在等待某个事件的发生。我已经尝试过前台服务，在 onStartCommand 中返回 START_STICKY，在 onTaskRemoved 中重启服务并使用 android:process 在单独的进程中运行服务。

我的服务类:

public class CallService  extends Service {

@Override
public IBinder onBind(Intent intent) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public int onStartCommand (Intent intent, int flags, int startId){
    NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
    builder.setSmallIcon(R.drawable.icon)
            .setContentTitle("title")
            .setContentText("text")
            .setAutoCancel(true)
            .setOngoing(true);
    Intent startIntent = new Intent(this, MainActivity.class);
    PendingIntent contentIntent = PendingIntent.getActivity(this, 1, startIntent, 0);
    builder.setContentIntent(contentIntent);
    this.startForeground(1, builder.build());
    super.onStartCommand(intent, flags, startId);
    return START_STICKY;
}

@Override
public void onCreate() {
    super.onCreate();
}

@Override
public void onDestroy() {
    super.onDestroy();

}
@Override
public void onTaskRemoved(Intent rootIntent){
    Intent restartServiceIntent = new Intent(getApplicationContext(), this.getClass());
    restartServiceIntent.setPackage(getPackageName());

    PendingIntent restartServicePendingIntent = PendingIntent.getService(getApplicationContext(), 1, restartServiceIntent, PendingIntent.FLAG_ONE_SHOT);
    AlarmManager alarmService = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
    alarmService.set(
            AlarmManager.ELAPSED_REALTIME,
            SystemClock.elapsedRealtime() + 1000,
            restartServicePendingIntent);

    super.onTaskRemoved(rootIntent);
}

我的AndroidManifest.xml

<service android:name=".CallService" android:persistent="true">
            <intent-filter>
                <action android:name="cz.volamakler.CallService" />
            </intent-filter>
</service>
    <receiver android:name=".CallReceiver">
        <intent-filter>
            <action android:name="android.intent.action.PHONE_STATE" />
        </intent-filter>
        <intent-filter>
            <action android:name="android.intent.action.NEW_OUTGOING_CALL" />
        </intent-filter>
    </receiver>

我尝试使用广播接收器，但它也被主要 Activity 杀死了。

    public abstract class PhoneCallReceiver extends BroadcastReceiver {

    //The receiver will be recreated whenever android feels like it.  We need a static variable to remember data between instantiations

    private static int lastState = TelephonyManager.CALL_STATE_IDLE;
    private static Date callStartTime;
    private static boolean isIncoming;
    private static String savedNumber;  //because the passed incoming is only valid in ringing


    @Override
    public void onReceive(Context context, Intent intent) {

        //We listen to two intents.  The new outgoing call only tells us of an outgoing call.  We use it to get the number.
        if (intent.getAction().equals("android.intent.action.NEW_OUTGOING_CALL")) {
            savedNumber = intent.getExtras().getString("android.intent.extra.PHONE_NUMBER");
        }
        else{
            String stateStr = intent.getExtras().getString(TelephonyManager.EXTRA_STATE);
            String number = intent.getExtras().getString(TelephonyManager.EXTRA_INCOMING_NUMBER);
            int state = 0;
            if(stateStr.equals(TelephonyManager.EXTRA_STATE_IDLE)){
                state = TelephonyManager.CALL_STATE_IDLE;
            }
            else if(stateStr.equals(TelephonyManager.EXTRA_STATE_OFFHOOK)){
                state = TelephonyManager.CALL_STATE_OFFHOOK;
            }
            else if(stateStr.equals(TelephonyManager.EXTRA_STATE_RINGING)){
                state = TelephonyManager.CALL_STATE_RINGING;
            }

            onCallStateChanged(context, state, number);
        }
    }

    //Derived classes should override these to respond to specific events of interest
    protected void onIncomingCallStarted(Context ctx, String number, Date start){}
    protected void onOutgoingCallStarted(Context ctx, String number, Date start){}
    protected void onIncomingCallEnded(Context ctx, String number, Date start, Date end){}
    protected void onOutgoingCallEnded(Context ctx, String number, Date start, Date end){}
    protected void onMissedCall(Context ctx, String number, Date start){}

    //Deals with actual events

    //Incoming call-  goes from IDLE to RINGING when it rings, to OFFHOOK when it's answered, to IDLE when its hung up
    //Outgoing call-  goes from IDLE to OFFHOOK when it dials out, to IDLE when hung up
    public void onCallStateChanged(Context context, int state, String number) {
        if(lastState == state){
            //No change, debounce extras
            return;
        }
        switch (state) {
            case TelephonyManager.CALL_STATE_RINGING:
                isIncoming = true;
                callStartTime = new Date();
                savedNumber = number;
                onIncomingCallStarted(context, number, callStartTime);
                break;
            case TelephonyManager.CALL_STATE_OFFHOOK:
                //Transition of ringing->offhook are pickups of incoming calls.  Nothing done on them
                if(lastState != TelephonyManager.CALL_STATE_RINGING){
                    isIncoming = false;
                    callStartTime = new Date();
                    onOutgoingCallStarted(context, savedNumber, callStartTime);
                }
                break;
            case TelephonyManager.CALL_STATE_IDLE:
                //Went to idle-  this is the end of a call.  What type depends on previous state(s)
                if(lastState == TelephonyManager.CALL_STATE_RINGING){
                    //Ring but no pickup-  a miss
                    onMissedCall(context, savedNumber, callStartTime);
                }
                else if(isIncoming){
                    onIncomingCallEnded(context, savedNumber, callStartTime, new Date());
                }
                else{
                    onOutgoingCallEnded(context, savedNumber, callStartTime, new Date());
                }
                break;
        }
        lastState = state;
    }
}

public class CallReceiver extends PhoneCallReceiver {

    @Override
    protected void onIncomingCallStarted(Context ctx, String number, Date start) {
        Toast.makeText(ctx, "Call!", Toast.LENGTH_LONG).show();
    }

    @Override
    protected void onOutgoingCallStarted(Context ctx, String number, Date start) {
    }

    @Override
    protected void onIncomingCallEnded(Context ctx, String number, Date start, Date end) {
    }

    @Override
    protected void onOutgoingCallEnded(Context ctx, String number, Date start, Date end) {
    }

    @Override
    protected void onMissedCall(Context ctx, String number, Date start) {
    }
}

Answer 1

发生这种情况是因为您在同一个 ui 线程中运行您的服务。使用的 Looper 与您启动服务的应用程序的 ui 线程相同。您需要执行以下操作:

创建一个单独的处理程序线程。然后在 handlemessage 中执行您的任务。

  public class CallService  extends Service {
            private Looper mServiceLooper;
          private ServiceHandler mServiceHandler;

          // Handler that receives messages from the thread
          private final class ServiceHandler extends Handler {
              public ServiceHandler(Looper looper) {
                  super(looper);
              }
              @Override
              public void handleMessage(Message msg) {
                  // Normally we would do some work here, like download a file.
                  // For our sample, we just sleep for 5 seconds.
                  long endTime = System.currentTimeMillis() + 5*1000;
                  while (System.currentTimeMillis() < endTime) {
                      synchronized (this) {
                          try {
                              wait(endTime - System.currentTimeMillis());
                          } catch (Exception e) {
                          }
                      }
                  }
                  // Stop the service using the startId, so that we don't stop
                  // the service in the middle of handling another job
                  stopSelf(msg.arg1);
              }
          }
            @Override
            public IBinder onBind(Intent intent) {
                // TODO Auto-generated method stub
                return null;
            }

            @Override
            public int onStartCommand (Intent intent, int flags, int startId){
// For each start request, send a message to start a job and deliver the
      // start ID so we know which request we're stopping when we finish the job
      Message msg = mServiceHandler.obtainMessage();
      msg.arg1 = startId;
      mServiceHandler.sendMessage(msg);

                return START_STICKY;
            }
           @Override
      public void onCreate() {
        // Start up the thread running the service.  Note that we create a
        // separate thread because the service normally runs in the process's
        // main thread, which we don't want to block.  We also make it
        // background priority so CPU-intensive work will not disrupt our UI.
        HandlerThread thread = new HandlerThread("ServiceStartArguments",
                Process.THREAD_PRIORITY_BACKGROUND);
        thread.start();

        // Get the HandlerThread's Looper and use it for our Handler
        mServiceLooper = thread.getLooper();
        mServiceHandler = new ServiceHandler(mServiceLooper);
      }
            @Override
            public void onDestroy() {
                super.onDestroy();

            }
            @Override
            public void onTaskRemoved(Intent rootIntent){
                Intent restartServiceIntent = new Intent(getApplicationContext(), this.getClass());
                restartServiceIntent.setPackage(getPackageName());

                PendingIntent restartServicePendingIntent = PendingIntent.getService(getApplicationContext(), 1, restartServiceIntent, PendingIntent.FLAG_ONE_SHOT);
                AlarmManager alarmService = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
                alarmService.set(
                        AlarmManager.ELAPSED_REALTIME,
                        SystemClock.elapsedRealtime() + 1000,
                        restartServicePendingIntent);

                super.onTaskRemoved(rootIntent);
            }
            }

希望对您有所帮助。