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：

[xhtml] view
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<?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：

[java] view
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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：

[java] view
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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);

}

}

}