Android提高之MediaPlayer播放网络音频的实现方法

前面有文章曾经地介绍过mediaplayer的基本用法，这里就更加深入地讲解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如下图所示：

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);
 }
 }
}

感兴趣的读者可以亲自动手调试一下本文实例代码，相信会对大家理解android程序设计起到一定的促进作用。