Android服务尚未绑定

Question

I am trying to make a button that will change the interruption filter (None, Priority, All) in Android Lollipop. When I press the button, the log says Notification listener service not yet bound. . The service starts, so I guess I am trying to bind it wrong? I get the "NLS Started" log but not the "NLS Bound" one. Here is my code:

MainActivity.java :

public class MainActivity extends Activity {
    private NotificationService notifs;
    private ServiceConnection connection;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        notifs = new NotificationService();
        connection = new ServiceConnection() {
            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
                Log.d("NOTIF", "NLS Started");
                NotificationService.ServiceBinder binder = (NotificationService.ServiceBinder)service;
                notifs = binder.getService();
            }

            @Override
            public void onServiceDisconnected(ComponentName name) {
                Log.d("NOTIF", "NLS Stopped");
            }
        };
        Intent intent = new Intent(this, NotificationService.class);
        startService(intent);
        bindService(intent, connection, Context.BIND_AUTO_CREATE);
        if(notifs.isBound()) {
            Log.d("NOTIFS", "NLS Bound");
        }

        final Button b = (Button) findViewById(R.id.b);
        b.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (notifs.getCurrentInterruptionFilter() == NotificationService.INTERRUPTION_FILTER_NONE) {
                    //set all
                    b.setBackground(ContextCompat.getDrawable(MainActivity.this, R.drawable.ic_ring_volume));
                    notifs.requestInterruptionFilter(NotificationService.INTERRUPTION_FILTER_ALL);
                } else if (notifs.getCurrentInterruptionFilter() == NotificationListenerService.INTERRUPTION_FILTER_PRIORITY) {
                    //set none
                    b.setBackground(ContextCompat.getDrawable(MainActivity.this, R.drawable.ic_ring_off));
                    notifs.requestInterruptionFilter(NotificationService.INTERRUPTION_FILTER_NONE);
                } else {
                    //set priority
                    b.setBackground(ContextCompat.getDrawable(MainActivity.this, R.drawable.ic_ring_priority));
                    notifs.requestInterruptionFilter(NotificationService.INTERRUPTION_FILTER_PRIORITY);
                }
            }
        });
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        unbindService(connection);
        connection = null;
    }
}

NotificationService.java :

public class NotificationService extends NotificationListenerService {
    private final IBinder binder = new ServiceBinder();
    private boolean isBound = false;

    public NotificationService() {
    }

    public class ServiceBinder extends Binder {
        NotificationService getService() {
            return NotificationService.this;
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        isBound = true;
        return binder;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startid) {
        return START_STICKY;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Log.d("NOTIF", "Started");
        Toast.makeText(NotificationService.this, "NLS Started", Toast.LENGTH_SHORT).show();
    }

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

    public boolean isBound() {
        return isBound;
    }
}

Answer 1

Service connection works with bindService() method only. Therefore, if you're getting "NLS Started" that means code from onServiceConnected() method of service connection has been executed which indicates that your service has been successfully bound with your respective activity.

As far as "NLS Bound" is concerned, sometimes service connection takes a second or two to bind the service with the activity. This delay will not stop the rest of your code from working ie the if statement below the bindService() method will get executed even before the service has been bound with your activity. For this reason we use the service connection. The service connection receives the service object when it is created and is also informed if the service is destroyed. See the following link for more details:-

http://developer.android.com/reference/android/content/Context.html#bindService(android.content.Intent,android.content.ServiceConnection,int)