详解Android应用开发--MP3音乐播放器代码实现（一）

/** * 用于从数据库中查询歌曲的信息，保存在List当中 * * @return */ public List<Mp3Info> getMp3Infos() {   Cursor cursor = getContentResolver().query(     MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null, null,     MediaStore.Audio.Media.DEFAULT_SORT_ORDER);   List<Mp3Info> mp3Infos = new ArrayList<Mp3Info>();   for (int i = 0; i < cursor.getCount(); i++) {     Mp3Info mp3Info = new Mp3Info();     cursor.moveToNext();     long id = cursor.getLong(cursor       .getColumnIndex(MediaStore.Audio.Media._ID));  //音乐id     String title = cursor.getString((cursor        .getColumnIndex(MediaStore.Audio.Media.TITLE)));//音乐标题     String artist = cursor.getString(cursor       .getColumnIndex(MediaStore.Audio.Media.ARTIST));//艺术家     long duration = cursor.getLong(cursor       .getColumnIndex(MediaStore.Audio.Media.DURATION));//时长     long size = cursor.getLong(cursor       .getColumnIndex(MediaStore.Audio.Media.SIZE)); //文件大小     String url = cursor.getString(cursor       .getColumnIndex(MediaStore.Audio.Media.DATA));       //文件路径   int isMusic = cursor.getInt(cursor     .getColumnIndex(MediaStore.Audio.Media.IS_MUSIC));//是否为音乐   if (isMusic != 0) {   //只把音乐添加到集合当中     mp3Info.setId(id);     mp3Info.setTitle(title);     mp3Info.setArtist(artist);     mp3Info.setDuration(duration);     mp3Info.setSize(size);     mp3Info.setUrl(url);     mp3Infos.add(mp3Info);     }   } return mp3Infos; } 

/**    * 填充列表    * @param mp3Infos    */   public void setListAdpter(List<Mp3Info> mp3Infos) {     List<HashMap<String, String>> mp3list = new ArrayList<HashMap<String, String>>();     for (Iterator iterator = mp3Infos.iterator(); iterator.hasNext();) {       Mp3Info mp3Info = (Mp3Info) iterator.next();       HashMap<String, String> map = new HashMap<String, String>();       map.put("title", mp3Info.getTitle());       map.put("Artist", mp3Info.getArtist());       map.put("duration", String.valueOf(mp3Info.getDuration()));       map.put("size", String.valueOf(mp3Info.getSize()));       map.put("url", mp3Info.getUrl());       mp3list.add(map);     }     mAdapter = new SimpleAdapter(this, mp3list,         R.layout.music_list_item_layout, new String[] { "title", "Artist", "duration" },         new int[] { R.id.music_title, R.id.music_Artist, R.id.music_duration });     mMusiclist.setAdapter(mAdapter);     } 

mMusiclist = (ListView) findViewById(R.id.music_list);     mMusiclist.setOnItemClickListener(new MusicListItemClickListener());     mp3Infos = getMp3Infos();     setListAdpter(getMp3Infos()); 

private class MusicListItemClickListener implements OnItemClickListener {   @Override   public void onItemClick(AdapterView<?> parent, View view, int position,       long id) {     if(mp3Infos != null) {       Mp3Info mp3Info = mp3Infos.get(position);       Log.d("mp3Info-->", mp3Info.toString());       Intent intent = new Intent();       intent.putExtra("url", mp3Info.getUrl());           intent.putExtra("MSG", AppConstant.PlayerMsg.PLAY_MSG);       intent.setClass(MainActivity.this, PlayerService.class);       startService(intent);    //启动服务     }   } } 

package com.wwj.sb.service;   import android.annotation.SuppressLint; import android.app.Service; import android.content.Intent; import android.media.MediaPlayer; import android.media.MediaPlayer.OnPreparedListener; import android.os.IBinder;  import com.wwj.sb.domain.AppConstant;  @SuppressLint("NewApi") public class PlayerService extends Service {   private MediaPlayer mediaPlayer = new MediaPlayer();    //媒体播放器对象   private String path;            //音乐文件路径   private boolean isPause;          //暂停状态      @Override   public IBinder onBind(Intent arg0) {     return null;   }      @Override   public int onStartCommand(Intent intent, int flags, int startId) {     if(mediaPlayer.isPlaying()) {       stop();     }     path = intent.getStringExtra("url");         int msg = intent.getIntExtra("MSG", 0);     if(msg == AppConstant.PlayerMsg.PLAY_MSG) {       play(0);     } else if(msg == AppConstant.PlayerMsg.PAUSE_MSG) {       pause();     } else if(msg == AppConstant.PlayerMsg.STOP_MSG) {       stop();     }     return super.onStartCommand(intent, flags, startId);   }       /**    * 播放音乐    * @param position    */   private void play(int position) {     try {       mediaPlayer.reset();//把各项参数恢复到初始状态       mediaPlayer.setDataSource(path);       mediaPlayer.prepare(); //进行缓冲       mediaPlayer.setOnPreparedListener(new PreparedListener(position));//注册一个监听器     }     catch (Exception e) {       e.printStackTrace();     }   }      /**    * 暂停音乐    */   private void pause() {     if (mediaPlayer != null && mediaPlayer.isPlaying()) {       mediaPlayer.pause();       isPause = true;     }   }      /**    * 停止音乐    */   private void stop(){     if(mediaPlayer != null) {       mediaPlayer.stop();       try {         mediaPlayer.prepare(); // 在调用stop后如果需要再次通过start进行播放,需要之前调用prepare函数       } catch (Exception e) {         e.printStackTrace();       }     }   }         @Override   public void onDestroy() {     if(mediaPlayer != null){       mediaPlayer.stop();       mediaPlayer.release();     }   }   /**    *    * 实现一个OnPrepareLister接口,当音乐准备好的时候开始播放    *    */   private final class PreparedListener implements OnPreparedListener {     private int positon;          public PreparedListener(int positon) {       this.positon = positon;     }          @Override     public void onPrepared(MediaPlayer mp) {       mediaPlayer.start();  //开始播放       if(positon > 0) {  //如果音乐不是从头播放         mediaPlayer.seekTo(positon);       }     }   }    }