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Android提高21篇之二十一：MediaPlayer播放網絡視頻

編輯：關於android開發

上次講解了MediaPlayer播放網絡音頻，介紹了MediaPlayer關於網絡音頻的緩沖和進度條控制的方法，這次再講解MediaPlayer播放網絡視頻。播放網絡視頻比播放網絡音頻多需要一個SurfaceView而已，已經熟悉MediaPlayer播放網絡音頻之後，相信大家對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：

　　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/HTML代碼

<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">
<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 android:layout_height="wrap_content" android:id="@+id/btnPause"
android:text="暫停" android:layout_width="80dip">
<button android:layout_height="wrap_content"
android:layout_width="80dip" android:text="停止" android:id="@+id/btnStop">
<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">

　　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：

Java代碼

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：

Java代碼

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之後自動播放
//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：

Java代碼

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);
}
}
}

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