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);
 }
 
 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 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;
 
 @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。

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