如何在删除回调后重用 Android-Handler

Question

我有一个服务，我在其中使用一个处理程序来每毫秒获取媒体播放器的时间。

但是，当我的服务未绑定到任何 activity 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 activity 时，我想通过在 Rebind/onBind();

上向它发布相同的回调来重用我的处理程序

但是，它不起作用。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

您可以使用以下方法移除回调

handleTime.removeCallbacksAndMessages(null);

您可以签到doc

Answer 2

如果你想重用你必须做的处理程序：

handler.removeCallbacksAndMessages(null);

在 removeCallbacksAndMessages 的文档中说...

Remove any pending posts of callbacks and sent messages whose obj is token. If token is null, all callbacks and messages will be removed.

希望对你有帮助！

如何在删除回调后重用 Android-Handler

How to reuse Android-Handler after removing callbacks

java

android

handler

android-threading