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：
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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>
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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：
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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");
}
}
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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：
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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);
}
}
}
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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。