Android提高之MediaPlayer播放网络视频的实现方法

前面讲解了MediaPlayer播放网络音频，主要介绍了MediaPlayer关于网络音频的缓冲和进度条控制的方法，本文再来讲解一下MediaPlayer播放网络视频的方法。播放网络视频比播放网络音频需要多一个SurfaceView而已，在已经熟悉了MediaPlayer播放网络音频之后，相信大家对本文所述的播放网络视频也能很快地掌握。

先来看看本文程序运行截图，如下所示：

本文程序的视频来自http://daily3gp.com，大家可以替换程序中的视频链接，试试其他影片。

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">
<SurfaceView android:id="@+id/surfaceView1"
android:layout_height="fill_parent" android:layout_width="fill_parent"></SurfaceView>
<LinearLayout android:layout_height="wrap_content"
android:layout_width="fill_parent" android:layout_gravity="bottom"
android:orientation="vertical">
<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="播放网络视频"></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”、“SurfaceHolder生命周期”等功能，其中“SurfaceHolder生命周期”是视频与音频播放的最大区别，通过surfaceCreated()、surfaceDestroyed()、surfaceChanged()可以创建/释放某些资源。下面这个地方需要注意一下：

videoWidth = mediaPlayer.getVideoWidth();
videoHeight = mediaPlayer.getVideoHeight();
if (videoHeight != 0 && videoWidth != 0) {
arg0.start();
}

有些视频是android播放器不能播放的，不能播放时videoHeight=0，videoWidth=0，以此来判断是否播放视频。

Player.java源码如下：

package com.videoplayer;
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.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.SeekBar;
public class Player implements OnBufferingUpdateListener,
OnCompletionListener, MediaPlayer.OnPreparedListener,
SurfaceHolder.Callback {
private int videoWidth;
private int videoHeight;
public MediaPlayer mediaPlayer;
private SurfaceHolder surfaceHolder;
private SeekBar skbProgress;
private Timer mTimer=new Timer();
public Player(SurfaceView surfaceView,SeekBar skbProgress)
{
this.skbProgress=skbProgress;
surfaceHolder=surfaceView.getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
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
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
Log.e("mediaPlayer", "surface changed");
}
@Override
public void surfaceCreated(SurfaceHolder arg0) {
try {
 mediaPlayer = new MediaPlayer();
 mediaPlayer.setDisplay(surfaceHolder);
 mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
 mediaPlayer.setOnBufferingUpdateListener(this);
 mediaPlayer.setOnPreparedListener(this);
} catch (Exception e) {
 Log.e("mediaPlayer", "error", e);
}
Log.e("mediaPlayer", "surface created");
}
@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
Log.e("mediaPlayer", "surface destroyed");
}
@Override
/**
* 通过onPrepared播放
*/
public void onPrepared(MediaPlayer arg0) {
videoWidth = mediaPlayer.getVideoWidth();
videoHeight = mediaPlayer.getVideoHeight();
if (videoHeight != 0 && videoWidth != 0) {
 arg0.start();
}
Log.e("mediaPlayer", "onPrepared");
}

@Override
public void onCompletion(MediaPlayer arg0) {
// TODO Auto-generated method stub
}
@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_videoplayer.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())*MediaPlayer.getDuration()。

test_videoplayer.java源码如下：

package com.videoplayer;
import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.SeekBar;
public class test_videoplayer extends Activity {
private SurfaceView surfaceView;
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);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
surfaceView = (SurfaceView) this.findViewById(R.id.surfaceView1);

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(surfaceView, skbProgress);
}
class ClickEvent implements OnClickListener {
@Override
public void onClick(View arg0) {
 if (arg0 == btnPause) {
 player.pause();
 } else if (arg0 == btnPlayUrl) {
 String url="http://daily3gp.com/vids/family_guy_penis_car.3gp";
 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);
}
}
}

感兴趣的读者可以自己动手测试一下本文实例代码，相信对大家进行Android程序开发有一定的借鉴作用。