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() {
		@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);
		}
	}

}