Android 音乐播放器。

package com.king.android.media;

import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

import com.king.android.R;


public class MusicBActivity extends Activity implements OnClickListener{
    public static final String TAG="MusicActivity";
    static List<File> allFiles = new ArrayList<File>();
    private int mCurrentJMusic = 0;        // 当前播放的音乐
    private MediaPlayer mMediaPlayer = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        refreshFile(getSDCardPath(),".mp3");
        if(allFiles.size()<=0){
            Toast.makeText(MusicBActivity.this, "没有歌曲", Toast.LENGTH_SHORT).show();
            finish();
        }
        mMediaPlayer = new MediaPlayer();
        initView();
    }
    
    public String getSDCardPath(){
        String sdPath = null;
        boolean hasCard = Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
        if(hasCard){
            sdPath =  Environment.getExternalStorageDirectory().toString();
        }else{
            sdPath = Environment.getDataDirectory().toString();
        }
        return sdPath;
    }
    private void initView(){
        setContentView(R.layout.media_layout);
        
        Button btnMedia = (Button) findViewById(R.id.btn_last);
        btnMedia.setOnClickListener(this);
        
        btnMedia = (Button) findViewById(R.id.btn_pause);
        btnMedia.setOnClickListener(this);
        
        btnMedia = (Button) findViewById(R.id.btn_stop);
        btnMedia.setOnClickListener(this);
        
        btnMedia = (Button) findViewById(R.id.btn_play);
        btnMedia.setOnClickListener(this);
        
        btnMedia = (Button) findViewById(R.id.btn_next);
        btnMedia.setOnClickListener(this);
        
    }

    @Override
    public void onClick(View v) {
        switch(v.getId()){
        case R.id.btn_play:
            playMusic(allFiles.get(mCurrentJMusic));
            break;
            
        case R.id.btn_next:
            nextMusic();
            break;
        case R.id.btn_last:
            FrontMusic();
            break;
            
        case R.id.btn_pause:
            if(mMediaPlayer.isPlaying()){
                //暂停
                mMediaPlayer.pause();
            }else{
                //播放
                mMediaPlayer.start();
            }
            break;
            
        case R.id.btn_stop:
            //是否在播放
            if(mMediaPlayer.isPlaying()){
                //重置MediaPlayer到初始状态
                mMediaPlayer.reset();
            }
            break;
    
        }
    }

    private void playMusic(File    file){
        try{
        //重置MediaPlayer
        mMediaPlayer.reset();
        //设置播放文件 的路径
        //mMediaPlayer.setDataSource(file.getAbsolutePath()+File.separator+file.getName());
        mMediaPlayer.setDataSource(file.getAbsolutePath());
        //播放文件
        mMediaPlayer.prepare();
        //开始播放
        mMediaPlayer.start();
        mMediaPlayer.setOnCompletionListener(new OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                //播放完成后，进行下一首。
                nextMusic();
            }
        });
        }catch(Exception e){
            e.printStackTrace();
        }
    }
    
    //下一首    
    private void nextMusic(){
        if(++mCurrentJMusic>=allFiles.size()){
            mCurrentJMusic = 0;
        }else{
            playMusic(allFiles.get(mCurrentJMusic));
        }
    }
    
    //上一首
    private void FrontMusic(){
        if(--mCurrentJMusic>=0){
            mCurrentJMusic = allFiles.size();
        }else{
            playMusic(allFiles.get(mCurrentJMusic));
        }
    }
    
    	/**	 * 	递归法获取文件夹文件	 *TODO：TODO	 *Author：Andy.Liu	 *Create Time：2012-7-29 下午11:40:33	 *TAG：@param path   文件路径，一般选择根目录	 *TAG：@param fileType 文件类型。	 *Return：void	 */    public void refreshFile(String path,String fileType){
        File file = new File(path);
        File[] files = file.listFiles();
        if(null==files)
            return;
        
        for(int i = 0;i<files.length;i++){
            if(files[i].isDirectory()){
                refreshFile(files[i].getAbsolutePath(),fileType);        //注意这里的递归方法 
            }else{
                if(files[i].getName().endsWith(fileType))
                    allFiles.add(files[i]);
            }
        }
    }
   
}

获取文件夹中的文件夹，方法有很多，但递归法效率最高，要用最好的办法去解决问题。。。