Android提高第二十篇之MediaPlayer播放网络音频

本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！

     以前曾经地介绍过MediaPlayer的基本用法，这里就深入地讲解MediaPlayer的在线播放功能。本文主要实现MediaPlayer在线播放音频的功能，由于在线视频播放比在线音频播放复杂，因此先介绍在线音频播放的实现，这样可以帮助大家逐步深入了解MediaPlayer的在线播放功能。先来看看本文程序运行的结果：

main.xml的源码如下：

<?xml version="1.0" encoding="utf-8"?><FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_height="fill_parent" android:layout_width="fill_parent"><LinearLayout android:layout_height="wrap_content"android:layout_width="fill_parent" android:orientation="vertical"android:layout_gravity="top"><LinearLayout android:orientation="horizontal"android:layout_gravity="center_horizontal" android:layout_marginTop="4.0dip"android:layout_height="wrap_content" android:layout_width="wrap_content"><Button android:layout_width="wrap_content"android:layout_height="wrap_content" android:id="@+id/btnPlayUrl"android:text="播放网络音频"></Button><Button android:layout_height="wrap_content" android:id="@+id/btnPause"android:text="暂停" android:layout_width="80dip"></Button><Button android:layout_height="wrap_content"android:layout_width="80dip" android:text="停止" android:id="@+id/btnStop"></Button></LinearLayout><LinearLayout android:orientation="horizontal"android:layout_width="fill_parent" android:layout_height="wrap_content"android:layout_marginBottom="20dip"><SeekBar android:paddingRight="10dip" android:layout_gravity="center_vertical"android:paddingLeft="10dip" android:layout_weight="1.0"android:layout_height="wrap_content" android:layout_width="wrap_content"android:id="@+id/skbProgress" android:max="100"></SeekBar></LinearLayout></LinearLayout></FrameLayout>

Player.java是本文的核心，Player.java实现了“进度条更新”、“数据缓冲”等功能，虽然不是很复杂的功能，但却是非常有用的功能。Player.java源码如下：

package com.musicplayer;import java.io.IOException;import java.util.Timer;import java.util.TimerTask;import android.media.AudioManager;import android.media.MediaPlayer;import android.media.MediaPlayer.OnBufferingUpdateListener;import android.media.MediaPlayer.OnCompletionListener;import android.os.Handler;import android.os.Message;import android.util.Log;import android.widget.SeekBar;public class Player implements OnBufferingUpdateListener,OnCompletionListener, MediaPlayer.OnPreparedListener{public MediaPlayer mediaPlayer;private SeekBar skbProgress;private Timer mTimer=new Timer();public Player(SeekBar skbProgress){this.skbProgress=skbProgress;try {mediaPlayer = new MediaPlayer();mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);mediaPlayer.setOnBufferingUpdateListener(this);mediaPlayer.setOnPreparedListener(this);} catch (Exception e) {Log.e("mediaPlayer", "error", e);}mTimer.schedule(mTimerTask, 0, 1000);}/******************************************************* * 通过定时器和Handler来更新进度条 ******************************************************/TimerTask mTimerTask = new TimerTask() {@Overridepublic void run() {if(mediaPlayer==null)return;if (mediaPlayer.isPlaying() && skbProgress.isPressed() == false) {handleProgress.sendEmptyMessage(0);}}};Handler handleProgress = new Handler() {public void handleMessage(Message msg) {int position = mediaPlayer.getCurrentPosition();int duration = mediaPlayer.getDuration();if (duration > 0) {long pos = skbProgress.getMax() * position / duration;skbProgress.setProgress((int) pos);}};};//*****************************************************public void play(){mediaPlayer.start();}public void playUrl(String videoUrl){try {mediaPlayer.reset();mediaPlayer.setDataSource(videoUrl);mediaPlayer.prepare();//prepare之后自动播放//mediaPlayer.start();} catch (IllegalArgumentException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalStateException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}public void pause(){mediaPlayer.pause();}public void stop(){if (mediaPlayer != null) { mediaPlayer.stop(); mediaPlayer.release(); mediaPlayer = null; } }@Override/** * 通过onPrepared播放 */public void onPrepared(MediaPlayer arg0) {arg0.start();Log.e("mediaPlayer", "onPrepared");}@Overridepublic void onCompletion(MediaPlayer arg0) {Log.e("mediaPlayer", "onCompletion");}@Overridepublic void onBufferingUpdate(MediaPlayer arg0, int bufferingProgress) {skbProgress.setSecondaryProgress(bufferingProgress);int currentProgress=skbProgress.getMax()*mediaPlayer.getCurrentPosition()/mediaPlayer.getDuration();Log.e(currentProgress+"% play", bufferingProgress + "% buffer");}}

test_musicplayer.java是主程序，负责调用Player类，其中关键部分是SeekBarChangeEvent这个SeekBar拖动的事件：SeekBar的Progress是0~SeekBar.getMax()之内的数，而MediaPlayer.seekTo()的参数是0~MediaPlayer.getDuration()之内数，所以MediaPlayer.seekTo()的参数是(progress/seekBar.getMax())*player.mediaPlayer.getDuration()。

test_musicplayer.java源码如下：

package com.musicplayer;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.SeekBar;public class test_musicplayer extends Activity {private Button btnPause, btnPlayUrl, btnStop;private SeekBar skbProgress;private Player player;/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);this.setTitle("在线音乐播放---hellogv编写");btnPlayUrl = (Button) this.findViewById(R.id.btnPlayUrl);btnPlayUrl.setOnClickListener(new ClickEvent());btnPause = (Button) this.findViewById(R.id.btnPause);btnPause.setOnClickListener(new ClickEvent());btnStop = (Button) this.findViewById(R.id.btnStop);btnStop.setOnClickListener(new ClickEvent());skbProgress = (SeekBar) this.findViewById(R.id.skbProgress);skbProgress.setOnSeekBarChangeListener(new SeekBarChangeEvent());player = new Player(skbProgress);}class ClickEvent implements OnClickListener {@Overridepublic void onClick(View arg0) {if (arg0 == btnPause) {player.pause();} else if (arg0 == btnPlayUrl) {//在百度MP3里随便搜索到的,大家可以试试别的链接String url="http://219.138.125.22/myweb/mp3/CMP3/JH19.MP3";player.playUrl(url);} else if (arg0 == btnStop) {player.stop();}}}class SeekBarChangeEvent implements SeekBar.OnSeekBarChangeListener {int progress;@Overridepublic void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) {// 原本是(progress/seekBar.getMax())*player.mediaPlayer.getDuration()this.progress = progress * player.mediaPlayer.getDuration()/ seekBar.getMax();}@Overridepublic void onStartTrackingTouch(SeekBar seekBar) {}@Overridepublic void onStopTrackingTouch(SeekBar seekBar) {// seekTo()的参数是相对与影片时间的数字，而不是与seekBar.getMax()相对的数字player.mediaPlayer.seekTo(progress);}}}