正在播放多首歌曲，

Question

大家好，我想在Android Studio中制作音樂應用。 當我在“回收者”視圖中選擇一首歌曲時，該歌曲將在新活動中開始播放，但是當我返回到歌曲列表並選擇新歌曲時，兩首歌曲都將開始播放，我希望第一首選擇的前一首歌曲停止播放並開始播放新歌曲，該怎么辦？

package com.recycler.hp.navigationbar;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnBufferingUpdateListener;
import android.media.MediaPlayer.OnCompletionListener;
import android.os.Bundle;
import android.os.Handler;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.SeekBar;

public class Revival_Activity extends Activity implements 
    OnClickListener, OnTouchListener, OnCompletionListener, OnBufferingUpdateListener {

    private ImageButton buttonPlayPause;
    private SeekBar seekBarProgress;
    String editTextSongURL;

    private MediaPlayer mediaPlayer;
    private int mediaFileLengthInMilliseconds; // this value contains the song duration in milliseconds. Look at getDuration() method in MediaPlayer class

    private final Handler handler = new Handler();

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_revival_);
        editTextSongURL=getIntent().getStringExtra("url");

        initView();

    }



    /**
     * This method initialise all the views in project
     */


    @SuppressLint("ClickableViewAccessibility")
    private void initView() {
        buttonPlayPause = (ImageButton) findViewById(R.id.ButtonTestPlayPause);
        buttonPlayPause.setOnClickListener(this);

        seekBarProgress = (SeekBar) findViewById(R.id.SeekBarTestPlay);
        seekBarProgress.setMax(99); // It means 100% .0-99
        seekBarProgress.setOnTouchListener(this);

        // editTextSongURL = getString(R.string.testsong_20_sec);
        mediaPlayer = new MediaPlayer();
        mediaPlayer.setOnBufferingUpdateListener(this);
        mediaPlayer.setOnCompletionListener(this);
    }

    /**
     * Method which updates the SeekBar primary progress by current song playing position
     */
    private void primarySeekBarProgressUpdater() {
        seekBarProgress.setProgress((int) (((float) mediaPlayer.getCurrentPosition() / mediaFileLengthInMilliseconds) * 100)); // This math construction give a percentage of "was playing"/"song length"
        if (mediaPlayer.isPlaying()) {
            Runnable notification = new Runnable() {
                public void run() {
                    primarySeekBarProgressUpdater();
                }
            };
            handler.postDelayed(notification, 1000);
        }
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.ButtonTestPlayPause) {
            /** ImageButton onClick event handler. Method which start/pause mediaplayer playing */
            try {
                mediaPlayer.setDataSource(editTextSongURL); // setup song from http://www.hrupin.com/wp-content/uploads/mp3/testsong_20_sec.mp3 URL to mediaplayer data source
                mediaPlayer.prepare(); // you must call this method after setup the datasource in setDataSource method. After calling prepare() the instance of MediaPlayer starts load data from URL to internal buffer.
            } catch (Exception e) {
                e.printStackTrace();
            }

            mediaFileLengthInMilliseconds = mediaPlayer.getDuration(); // gets the song length in milliseconds from URL

            if (!mediaPlayer.isPlaying()) {
                mediaPlayer.start();
                buttonPlayPause.setImageResource(R.drawable.pause);
            } else {
                mediaPlayer.pause();
                buttonPlayPause.setImageResource(R.drawable.play);
            }

            primarySeekBarProgressUpdater();
        }
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if (v.getId() == R.id.SeekBarTestPlay) {
            /** Seekbar onTouch event handler. Method which seeks MediaPlayer to seekBar primary progress position*/
            if (mediaPlayer.isPlaying()) {
                SeekBar sb = (SeekBar) v;
                int playPositionInMillisecconds = (mediaFileLengthInMilliseconds / 100) * sb.getProgress();
                mediaPlayer.seekTo(playPositionInMillisecconds);
            }
        }
        return false;
    }

    @Override
    public void onCompletion(MediaPlayer mp) {
        /** MediaPlayer onCompletion event handler. Method which calls then song playing is complete*/
        buttonPlayPause.setImageResource(R.drawable.play);
    }

    @Override
    public void onBufferingUpdate(MediaPlayer mp, int percent) {
        /** Method which updates the SeekBar secondary progress by current song loading from URL position*/
        seekBarProgress.setSecondaryProgress(percent);
    }
}

Answer 1

在recyclerview中進行選擇時，可能正在創建多個媒體播放器對象。 嘗試創建在整個應用程序中共享的媒體播放器的單例實例，並調用mediaplayer.release（），然后在播放新歌曲之前重新創建。