Android提高第二十篇之MediaPlayer播放网络音频（转）

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() {
         @Override
         public 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 block
             e.printStackTrace();
         } catch (IllegalStateException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.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");
     }

     @Override
     public void onCompletion(MediaPlayer arg0) {
         Log.e("mediaPlayer", "onCompletion");
     }

     @Override
     public 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. */
     @Override
     public 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 {

         @Override
         public 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;

         @Override
         public 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();
         }

         @Override
         public void onStartTrackingTouch(SeekBar seekBar) {

         }

         @Override
         public 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);
         }
     }

 }