当手机被锁定时,听音量按钮

我的应用程序中有一个服务在后端运行,当我按下按钮音量时服务可以启动,当按下按钮音量时停止服务.

public class SettingsContentObserver extends ContentObserver {


int previousVolume;
Context context;

public SettingsContentObserver(Context c, Handler handler) {
    super(handler);
    context=c;

    AudioManager audio = (AudioManager)        context.getSystemService(Context.AUDIO_SERVICE);
    previousVolume = audio.getStreamVolume(AudioManager.STREAM_RING);

}



@Override
public boolean deliverSelfNotifications() {
    return super.deliverSelfNotifications();
}

@Override
public void onChange(boolean selfChange) {
    super.onChange(selfChange);

    AudioManager audio = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
    int currentVolume = audio.getStreamVolume(AudioManager.STREAM_RING);

    int delta=previousVolume-currentVolume;



        if(delta > 0)
        {
            System.out.println("Decreased") ;
            Intent intent = new Intent(context, MyAlarmService.class);
            context.stopService(intent);
            previousVolume=currentVolume;
        }
        else if(delta < 0)
        {
              System.out.println("Increased");
              Intent intent = new Intent(context, MyAlarmService.class);
              context.startService(intent);
              previousVolume=currentVolume;
        }


}
}

当我的手机被锁定时(屏幕关闭时)我想做同样的事情,当我在网上搜索时,我发现我必须使用BroadcastReceivre,我测试它但它不起作用.

public class YourBoardcastReceiver extends BroadcastReceiver {
    @Override
public void onReceive(Context context, Intent intent) {


    Log.e("get something", "i dont know what!!");

    String intentAction = intent.getAction();
    KeyEvent event = null;
    if (Intent.ACTION_MEDIA_BUTTON.equals(intentAction)) {
        event = (KeyEvent) intent
            .getParcelableExtra(Intent.EXTRA_KEY_EVENT);
    }

    if (event == null) {
        return;
    }

    int keycode = event.getKeyCode();
    int action = event.getAction();
    long eventtime = event.getEventTime();

    if (keycode == KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE
        || keycode == KeyEvent.KEYCODE_HEADSETHOOK) {
    if (action == KeyEvent.ACTION_DOWN) {

            Intent intent1 = new Intent(context, MyAlarmService.class);
            context.stopService(intent1);

        if (isOrderedBroadcast()) {
            abortBroadcast();
        }

        else if (action == KeyEvent.ACTION_UP) {

              Intent intent11 = new Intent(context, MyAlarmService.class);
              context.startService(intent11);

        }

            if (isOrderedBroadcast()) {
                abortBroadcast();


    }
}
}
}


}

在android清单中我添加:

并且在关于methode oncrete的mainActivity中我添加:

AudioManager mAudioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
ComponentName mRemoteControlResponder = new ComponentName(getPackageName(),
YourBoardcastReceiver.class.getName());

请问,我可以给我一些帮助.