java - Android服务尚未绑定(bind)

Question

我正在尝试制作一个按钮来更改 Android Lollipop 中的中断过​​滤器(无、优先级、全部)。当我按下按钮时，日志显示 Notification listener service not yet bound.。服务启动了，所以我想我尝试绑定(bind)错误？我收到了 "NLS Started" 日志，但没有收到 "NLS Bound" 日志。这是我的代码:

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

服务连接仅适用于 bindService() 方法。因此，如果您获得“NLS Started”，这意味着来自服务连接的 onServiceConnected() 方法的代码已被执行，这表明您的服务已成功与您各自的 Activity 绑定(bind)。

就“NLS Bound”而言，有时服务连接需要一两秒钟才能将服务与 Activity 绑定(bind)。这种延迟不会阻止您的其余代码工作，即 bindService() 方法下面的 if 语句甚至会在服务与您的 Activity 绑定(bind)之前执行。为此，我们使用服务连接。服务连接在创建时接收服务对象，如果服务被销毁也会收到通知。有关详细信息，请参阅以下链接:-

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