Android调用startForeground 但不显示通知

有时候我们想使用startForeground提升Service的进程优先级，但是startForeground会在手机通知栏显示通知。为了去除通知，可以借助目标Service（ForegroundService ）和引导Service（ForegroundEnablingService），使用以下trick（不支持 Android 7.1）：

1. 正常启动ForegroundService ，调用startForeground并指明NOTIFICATION_ID 。

2. 启动ForegroundEnablingService，调用startForeground并指明相同NOTIFICATION_ID
   ，再关闭该Service，即可隐藏通知。

代码如下：

ForegroundService.java

public class ForegroundService extends Service {

    static ForegroundService instance;

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

        instance = this;

        if (startService(new Intent(this, ForegroundEnablingService.class)) == null)
            throw new RuntimeException("Couldn't find " + ForegroundEnablingService.class.getSimpleName());
    }

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

        instance = null;
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

}

ForegroundEnablingService.java

public class ForegroundEnablingService extends Service {

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        if (ForegroundService.instance == null)
            throw new RuntimeException(ForegroundService.class.getSimpleName() + " not running");

        //Set both services to foreground using the same notification id, resulting in just one notification
        startForeground(ForegroundService.instance);
        startForeground(this);

        //Cancel this service's notification, resulting in zero notifications
        stopForeground(true);

        //Stop this service so we don't waste RAM.
        //Must only be called *after* doing the work or the notification won't be hidden.
        stopSelf();

        return START_NOT_STICKY;
    }

    private static final int NOTIFICATION_ID = 10;

    private static void startForeground(Service service) {
        Notification notification = new Notification.Builder(service).getNotification();
        service.startForeground(NOTIFICATION_ID, notification);
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

}

AndroidManifest.xml

<service android:name=".ForegroundEnablingService" />
<service android:name=".ForegroundService" />

http://stackoverflow.com/questions/10962418/how-to-startforeground-without-showing-notification