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);
    }

 

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 {
    @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
        }
    }
}

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

    @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);
            }
        }
    }

}

public class MusicActivity extends Activity {
private boolean isStop = false;
private MediaPlayer mPlayer;
public final String TITLE = Environment.getExternalStorageDirectory()
+ "/iwantyourlove.mp3";

private File file;

private SeekBar seekBar;
private ImageView play;
private TextView title;

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.music_main);

initWidgets();

}

// 重新初始化播放器
public void initWidgets() {
play = (ImageView) findViewById(R.id.img_stop);
title = (TextView) findViewById(R.id.title);
seekBar = (SeekBar) findViewById(R.id.seek);

seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {

@Override
public void onStopTrackingTouch(SeekBar seekBar) {
//seekBar.setProgress(mPlayer.getCurrentPosition() *seekBar.getMax() / total);
//Log.i("sss", seekBar.getProgress()+"");
//mPlayer.seekTo(mPlayer.getCurrentPosition());
mPlayer.seekTo(seekBar.getProgress() * mPlayer.getDuration() /100 );
}

@Override
public void onStartTrackingTouch(SeekBar seekBar) {

}

@Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
// Log.i("progress", ""+progress);
// Log.i("qqq", seekBar.getProgress()+"");
// progress = currentPosition * 100 / duration;

//progress*duration/100
//mPlayer.seekTo(progress * mPlayer.getDuration() /100 );
}
});

file = new File(TITLE);

title.setText(file.getName());

mPlayer = new MediaPlayer();
try {
mPlayer.setDataSource(TITLE);
mPlayer.prepare();
} catch (Exception e) {
e.printStackTrace();
}
}

public void play(View v) {
if (!mPlayer.isPlaying()) {
mPlayer.start();
}
}

public void pause(View v) {
if (mPlayer.isPlaying()) {
mPlayer.pause();
}
}

public void replay(View v) {
mPlayer.reset();
initWidgets();// 重新构建播放器
// mPlayer.start();
play(v);
}

public void stop(View v) {
isStop = true;
mPlayer.stop();

play.setImageResource(R.drawable.player_play);
}

// 用图片代替按钮
public void playOrPause(View v) {
if (isStop) {// 停止后重新开始播放
mPlayer.reset();
initWidgets();
mPlayer.start();
play.setImageResource(R.drawable.player_pause);
isStop = false;
} else if (mPlayer.isPlaying()) {// 播放状态
play.setImageResource(R.drawable.player_play);
mPlayer.pause();
} else {// 暂停状态
play.setImageResource(R.drawable.player_pause);
mPlayer.start();
}

// 异步任务
new MusicTask().execute();
}

@Override
protected void onDestroy() {
super.onDestroy();
// 释放资源
mPlayer.release();
}

// 音乐播放异步任务
class MusicTask extends AsyncTask<Void, Void, Void> {
//int current = mPlayer.getCurrentPosition();// 当前播放是什么位置，
int total = mPlayer.getDuration(); // 音乐总共多长时间

@Override
protected Void doInBackground(Void... params) {
// 让SeekBar跟着音乐一起向右边走
while (mPlayer.getCurrentPosition() <= total&&!isStop) { //!isPause不是停止状态
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
publishProgress();
}
return null;
}

@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
// Log.i("msg", ""+mPlayer.getCurrentPosition() * 100 / total);
seekBar.setProgress(mPlayer.getCurrentPosition() *seekBar.getMax() / total);
}

@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
}
}
}