删除回调后，如何重复使用Android处理程序

Question

我有一项服务，我正在使用处理程序每毫秒来获取MediaPlayer的时间。

但是，当我的服务不绑定到任何活动时，我想从onunbind((中的处理程序中删除回调；服务方法。

当服务绑定到活动时，我想通过在Rebind/onbind((上发布相同的回调来重复使用我的处理程序。

但是，它行不通。需要帮助！

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Binder;
import android.os.Handler;
import android.os.IBinder;
import android.util.Log;
import androidx.annotation.Nullable;
import androidx.lifecycle.MutableLiveData;
import java.io.IOException;
public class MediaService extends Service {
    private static final String TAG = "MediaService";
    IBinder myBinder = new MyBinder();
    MediaPlayer mediaPlayer = new MediaPlayer();
    boolean isPrepared = false;
    MutableLiveData<Integer> currrentTime = new MutableLiveData<>();
    MutableLiveData<Integer> mediaPlayerDuration = new MutableLiveData<>();
    private Handler handlerTime;
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        handlerTime = new Handler();
        //readyTime method posts delayed runnable on the handler @recurring
        readyTime();
        return myBinder;
    }
    @Override
    public boolean onUnbind(Intent intent) {
          handlerTime.removeCallbacks(curTimeRunnable);
        return super.onUnbind(intent);
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Log.d(TAG, "onCreate: MediaService Created");
    }
    class MyBinder extends Binder {
        MediaService getService() {
            return MediaService.this;
        }
    }
    public void setPathAndPlay(String path) {
        isPrepared = false;
        mediaPlayer.reset();
        try {
            mediaPlayer.setDataSource(path);
            mediaPlayer.prepareAsync();
            mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
                @Override
                public void onPrepared(MediaPlayer mp) {
                    isPrepared = true;
                    mp.start();
                    mediaPlayerDuration.postValue(mediaPlayer.getDuration());
                }
            });
        } catch (IOException e) {
            Log.d(TAG, "setPathAndPlay: Error");
            e.printStackTrace();
        }

    }
    public boolean isMediaPlaying() {
        return this.mediaPlayer.isPlaying();
    }
    public void pause() {
        mediaPlayer.pause();
    }
    public void resume() {
        try {
            mediaPlayer.start();
        } catch (Exception e) {
        }
    }
    public void seekTo(int millis) {
        mediaPlayer.seekTo(millis);
    }
    public int getTimeTotal() {
        return mediaPlayer.getDuration();
    }
    public int getCurrentPos() {
        return mediaPlayer.getCurrentPosition();
    }
 Runnable curTimeRunnable = new Runnable() {
        @Override
        public void run() {
            currrentTime.postValue(mediaPlayer.getCurrentPosition());
            Log.d(TAG, "run: VALUE POSTED");
            if (handlerTime != null) {
                handlerTime.postDelayed(this, 1);
            }
        }
    };
    public void readyTime() {
        if (handlerTime != null) {
            handlerTime.postDelayed(curTimeRunnable, 1);
        }
    }

}

Answer 1

如果要重复使用处理程序，则必须执行：

handler.removeCallbacksAndMessages(null);

在文档中的删除backsandmessages中，它说...

删除所有待定的回调帖子，并发送了其OBJ为令牌的消息。如果令牌为null，则所有回调和消息将被删除。

我希望它能帮助您！

Answer 2

您可以使用以下方法

删除回调

handleTime.removeCallbacksAndMessages(null);

您可以在Doc