Android应用开发--MP3音乐播放器代码实现（一）
需求1：将内存卡中的MP3音乐读取出来并显示到列表当中
1.从数据库中查询所有音乐数据，保存到List集合当中，List当中存放的是Mp3Info对象2.迭代List集合，把每一个Mp3Info对象的所有属性，保存到Map对象当中3.定义一个List集合，把Map对象添加到List集合当中4.通过定义一个SimpleAdpter,调用setAdpter方法，将数据显示到列表当中
/*** 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idString 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);}
实现效果如图：
需求2：点击列表的每一项，启动一个服务来播放音乐
1.注册条目点击监听器OnItemClickListener
2.定义一个实现OnItemClickListener接口的内部类
3.定义一个继承Service的服务类PlayerServie
1.注册条目点击监听器OnItemClickListener
mMusiclist = (ListView) findViewById(R.id.music_list);mMusiclist.setOnItemClickListener(new MusicListItemClickListener());mp3Infos = getMp3Infos();setListAdpter(getMp3Infos());
2.定义一个实现OnItemClickListener接口的内部类
private class MusicListItemClickListener implements OnItemClickListener {@Overridepublic 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}}}
3.定义一个继承Service的服务类PlayerServie（未完善的Service类）
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@Overridepublic IBinder onBind(Intent arg0) {return null;}@Overridepublic 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();}}}@Overridepublic 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;}@Overridepublic 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);}}}}
以上代码实现了两个需求，显示音乐列表和实现列表点击事件启动Servic。下次会实现控制音乐播放的需求。
