前面講解了MediaPlayer播放網絡音頻，主要介紹了MediaPlayer關于網絡音頻的緩沖和進度條控制的方法，本文再來講解一下MediaPlayer播放網絡視頻的方法。播放網絡視頻比播放網絡音頻需要多一個SurfaceView而已，在已經熟悉了MediaPlayer播放網絡音頻之后，相信大家對本文所述的播放網絡視頻也能很快地掌握。
先來看看本文程序運行截圖，如下所示：
本文程序的視頻來自http://daily3gp.com，大家可以替換程序中的視頻鏈接，試試其他影片。
main.xml的源碼如下：
<?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="播放網絡視頻"></Button> <Button android:layout_height="wrap_content" android:id="@+id/btnPause" android:text="暫停" 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實現了“進度條更新”、“數據緩沖”、“SurfaceHolder生命周期”等功能，其中“SurfaceHolder生命周期”是視頻與音頻播放的最大區別，通過surfaceCreated()、surfaceDestroyed()、surfaceChanged()可以創建/釋放某些資源。下面這個地方需要注意一下：
videoWidth = mediaPlayer.getVideoWidth();videoHeight = mediaPlayer.getVideoHeight();if (videoHeight != 0 && videoWidth != 0) { arg0.start();}有些視頻是android播放器不能播放的，不能播放時videoHeight=0，videoWidth=0，以此來判斷是否播放視頻。
Player.java源碼如下：
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); } /******************************************************* * 通過定時器和Handler來更新進度條 ******************************************************/ 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之后自動播放 //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 /** * 通過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，負責調用Player類，其中關鍵部分是SeekBarChangeEvent這個SeekBar拖動的事件：SeekBar的Progress是0~SeekBar.getMax()之內的數，而MediaPlayer.seekTo()的參數是0~MediaPlayer.getDuration()之內數，所以MediaPlayer.seekTo()的參數是(progress/seekBar.getMax())*MediaPlayer.getDuration()。
test_videoplayer.java源碼如下：
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()的參數是相對與影片時間的數字，而不是與seekBar.getMax()相對的數字 player.mediaPlayer.seekTo(progress); } }}感興趣的讀者可以自己動手測試一下本文實例代碼，相信對大家進行Android程序開發有一定的借鑒作用。
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