android开发之MediaPlayer+Service MP3播放器

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

import android.app.ListActivity;
import android.apps.service.PlayerService;
import android.content.Intent;
import android.media.AudioManager;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.SeekBar;
import android.widget.Toast;

public class TestMediaPlayer extends ListActivity {
/* 前段时间刚学习Android时就觉得MediaPlayer是个很神奇的东西，就试着做了个简单的音乐播放器。
* 支持后台播放、进度条拖放、音量控制、读取sdCard音乐文件进行播放等。
* */
private Button playButton = null;
private Button mFrontButton = null;
private Button mLastButton = null;
private Button exit = null;
/* 声明音量管理器 */
private AudioManager mAudioManager = null;

/* 定义进度条 */
public static SeekBar audioSeekBar = null;

/* 定义音量大小 */
private SeekBar audioVolume = null;

/* 定于一个数据播放列表，用来存放从指定文件中搜索到的文件 */
public static List<String> mMusicList = new ArrayList<String>();

/* 定义音乐存放路径 */
// private static final String MUSIC_PATH = new String("/mnt/sdcard/"); //android 2.2
private static final String MUSIC_PATH = new String("/sdcard/");//android 2.1
/* 定义在播放列表中的当前选择项 */
public static int currentListItme = 0;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/* 更新列表 */
musicList();
/* 得到控件 */
playButton = (Button) findViewById(R.id.StartMusic);
mFrontButton = (Button) findViewById(R.id.FrontButton);
mLastButton = (Button) findViewById(R.id.LastMusic);
audioVolume = (SeekBar) findViewById(R.id.audioVolume);
exit = (Button)findViewById(R.id.exit);
audioSeekBar = (SeekBar) findViewById(R.id.seekbar01);
/* 播放、暂停监听 */
playButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {

playMusic(AppConstant.PlayerMag.PAUSE);
}
});
/* 监听下一首 */
mFrontButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
nextMusic();
}
});
/* 监听上一首 */
mLastButton.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
FrontMusic();
}
});
/*退出监听*/
exit.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.setClass(TestMediaPlayer.this, PlayerService.class);
stopService(intent);//停止Service
try {
TestMediaPlayer.this.finish();//关闭当前Activity
} catch (Throwable e) {
e.printStackTrace();
}

}
});
/* 播放进度监听 */
audioSeekBar.setOnSeekBarChangeListener(new SeekBarChangeEvent());
/*退出后再次进去程序时，进度条保持持续更新*/
if(PlayerService.mMediaPlayer!=null){
//设置进度条最大值
TestMediaPlayer.audioSeekBar.setMax(PlayerService.mMediaPlayer.getDuration());
audioSeekBar.setProgress(PlayerService.mMediaPlayer.getCurrentPosition());
}

/* 得到当前音量对象 */
mAudioManager = (AudioManager) getSystemService(AUDIO_SERVICE);
/* 把当前音量值赋给进度条 */
audioVolume.setProgress(mAudioManager
.getStreamVolume(AudioManager.STREAM_MUSIC));
/* 监听音量 */
audioVolume.setOnSeekBarChangeListener(new AudioVolumeChangeEvent());
}

public void playMusic(int action) {
Intent intent = new Intent();
intent.putExtra("MSG", action);
intent.setClass(TestMediaPlayer.this, PlayerService.class);

/* 启动service service要在AndroidManifest.xml注册如：<service></service>*/

startService(intent);
}

/* 检测sdcard MP3文件并加入到List列表 */
public void musicList() {
// 先清除list中的缓存
mMusicList.clear();
/* 从指定的路径中读取文件，并与播放列表关联 */
File home = new File(MUSIC_PATH);

System.out.println(home.canRead());
/* 读取指定类型的文件，在本程序，指定播放类型为mp3 */
if (home.listFiles(new MusicFilter()).length > 0) {
/* 读取文件 */
for (File file : home.listFiles(new MusicFilter())) {
mMusicList.add(file.getName());
}
/* 播放文件与播放列表关联 */
ArrayAdapter<String> musicList = new ArrayAdapter<String>(
TestMediaPlayer.this, R.layout.musictime, mMusicList);
setListAdapter(musicList);
}
}

/* 音量监听 */
class AudioVolumeChangeEvent implements SeekBar.OnSeekBarChangeListener {

@Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {

// mAudioManager.adjustVolume(AudioManager.ADJUST_LOWER, 0);
mAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress,
0);

}

@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}

@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}

}

/* 音乐选择监听 */
@Override
protected void onListItemClick(android.widget.ListView l, View v,
int position, long id) {
super.onListItemClick(l, v, position, id);
currentListItme = position;
playMusic(AppConstant.PlayerMag.PLAY_MAG);
}

/* 播放下一首 */
private void nextMusic() {
if (++currentListItme >= mMusicList.size()) {
Toast.makeText(TestMediaPlayer.this, "已到最后一首歌曲", Toast.LENGTH_SHORT)
.show();
currentListItme = mMusicList.size() - 1;
} else {
playMusic(AppConstant.PlayerMag.PLAY_MAG);
}
}

/* 播放上一首歌曲 */
private void FrontMusic() {
if (--currentListItme >= 0) {
playMusic(AppConstant.PlayerMag.PLAY_MAG);

} else {
Toast.makeText(TestMediaPlayer.this, "已到第一首歌曲", Toast.LENGTH_SHORT)
.show();
currentListItme = 0;
}
}
}

/* 播放文件选择类 */
class MusicFilter implements FilenameFilter {
public boolean accept(File dir, String name) {
/* 指定扩展名类型 ，可以加其他的音乐格式*/
return (name.endsWith(".mp3"));
}
}

/* 拖放进度监听 ，别忘了Service里面还有个进度条刷新*/
class SeekBarChangeEvent implements SeekBar.OnSeekBarChangeListener {

@Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
/*假设改变源于用户拖动*/
if (fromUser) {
PlayerService.mMediaPlayer.seekTo(progress);// 当进度条的值改变时，音乐播放器从新的位置开始播放
}
}

@Override
public void onStartTrackingTouch(SeekBar seekBar) {
PlayerService.mMediaPlayer.pause(); // 开始拖动进度条时，音乐暂停播放
}

@Override
public void onStopTrackingTouch(SeekBar seekBar) {
PlayerService.mMediaPlayer.start(); // 停止拖动进度条时，音乐开始播放
}
}

service类

首先建议不要把播放音乐放在Activity中，因为关闭Activity后就不能实现后台播放。所以播放音乐要放在Service中，我们只需要管理Activity与Service间的通信就好了。下面就是个Service类。直接看注释和代码：

[java]
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package android.apps.service;

import java.io.IOException;

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.IBinder;
import android.widget.Toast;

import android.apps.*;

public class PlayerService extends Service implements Runnable,
MediaPlayer.OnCompletionListener {
/* 定于一个多媒体对象 */
public static MediaPlayer mMediaPlayer = null;
// 是否单曲循环
private static boolean isLoop = false;
// 用户操作
private int MSG;

/* 定义要播放的文件夹路径 */
private static final String MUSIC_PATH = new String("/sdcard/");

@Override
public IBinder onBind(Intent intent) {
return null;// 这里的绑定没的用，上篇我贴出了如何将activity与service绑定的代码
}

@Override
public void onCreate() {
super.onCreate();
if (mMediaPlayer != null) {
mMediaPlayer.reset();
mMediaPlayer.release();
mMediaPlayer = null;
}
mMediaPlayer = new MediaPlayer();
/* 监听播放是否完成 */
mMediaPlayer.setOnCompletionListener(this);
}

@Override
public void onDestroy() {
super.onDestroy();

if (mMediaPlayer != null) {
mMediaPlayer.stop();
mMediaPlayer.release();
mMediaPlayer = null;
}

System.out.println("service onDestroy");
}
/*启动service时执行的方法*/
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
/*得到从startService传来的动作，后是默认参数，这里是我自定义的常量*/
MSG = intent.getIntExtra("MSG", AppConstant.PlayerMag.PLAY_MAG);
if (MSG == AppConstant.PlayerMag.PLAY_MAG) {
playMusic();
}
if (MSG == AppConstant.PlayerMag.PAUSE) {
if (mMediaPlayer.isPlaying()) {// 正在播放
mMediaPlayer.pause();// 暂停
} else {// 没有播放
mMediaPlayer.start();
}
}

return super.onStartCommand(intent, flags, startId);
}

@SuppressWarnings("static-access")
public void playMusic() {
try {
/* 重置多媒体 */
mMediaPlayer.reset();
/* 读取mp3文件 */
mMediaPlayer.setDataSource(MUSIC_PATH+TestMediaPlayer.mMusicList.get(TestMediaPlayer.currentListItme));
// Uri uri = Uri.parse(MUSIC_PATH+TestMediaPlayer.mMusicList.get(TestMediaPlayer.currentListItme));
//
// mMediaPlayer.create(PlayerService.this,uri);
/* 准备播放 */
mMediaPlayer.prepare();
/* 开始播放 */
mMediaPlayer.start();
/* 是否单曲循环 */
mMediaPlayer.setLooping(isLoop);
// 设置进度条最大值
TestMediaPlayer.audioSeekBar.setMax(PlayerService.mMediaPlayer
.getDuration());
new Thread(this).start();
} catch (IOException e) {
}

}

// 刷新进度条
@Override
public void run() {
int CurrentPosition = 0;// 设置默认进度条当前位置
int total = mMediaPlayer.getDuration();//
while (mMediaPlayer != null && CurrentPosition < total) {
try {
Thread.sleep(1000);
if (mMediaPlayer != null) {
CurrentPosition = mMediaPlayer.getCurrentPosition();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
TestMediaPlayer.audioSeekBar.setProgress(CurrentPosition);
}

}

@Override
public void onCompletion(MediaPlayer mp) {
/* 播放完当前歌曲，自动播放下一首 */

if (++TestMediaPlayer.currentListItme >= TestMediaPlayer.mMusicList
.size()) {
Toast.makeText(PlayerService.this, "已到最后一首歌曲", Toast.LENGTH_SHORT)
.show();
TestMediaPlayer.currentListItme--;
TestMediaPlayer.audioSeekBar.setMax(0);
} else {
playMusic();
}
}
}

参数封装

[java]
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/**
* @把参数这样封装易于管理和阅读
*
*/
public interface AppConstant {
public class PlayerMag{
public static final int PLAY_MAG=1;//开始播放
public static final int PAUSE=2;//暂停播放
}
}

详细代码下载：http://download.csdn.net/source/3318587