Android学习笔记（十五）-简易视频播放器

在Android中播放视频用到的也是MediaPlayer，展示视频通常使用SurfaceView控件。

在main.xml布局文件添加用于视频画面绘制的SurfaceView 控件：

<SurfaceView android:layout_width="fill_parent"android:layout_height="240dip"android:id="@+id/surfaceView"/>

MeidaPlayer播放视频相关API使用方法：

 SurfaceView surfaceView = (SurfaceView)this.findViewById(R.id.surfaceView);
 surfaceView.getHolder().setFixedSize(176, 144);  //设置分辨率
 /*下面设置Surface不维护自己的缓冲区，而是等待屏幕的渲染引擎将内容推送到用户面前*/
 surfaceView.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
 MediaPlayer mediaPlayer = new MediaPlayer();
 mediaPlayer.reset();//重置为初始状态
 mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
 /* 设置Video影片以SurfaceHolder播放 */
 mediaPlayer.setDisplay(surfaceView.getHolder());
 mediaPlayer.setDataSource("/mnt/sdcard/oppo.mp4");
 mediaPlayer.prepare();//缓冲
 mediaPlayer.start();//播放
 mediaPlayer.pause();//暂停播放
 mediaPlayer.start();//恢复播放
 mediaPlayer.stop();//停止播放
 mediaPlayer.release();//释放资源

下面介绍一个播放视频的简易例子，在模拟器上运行时最好用2.1, 2.1以后的模拟器播放视频时会有问题，视频播放同样需要处理一些来电类的情况，需要覆写Activity生命周期里的几个方法,需要注意的是，当Surface控件被其他Activity遮挡住是，会被销毁，所以需要为他写一个回调函数，否则当当前Activity被其他Activity打断后，又回到当前Activity是，视频播放界面会是黑屏。

详细代码：

布局文件layout/main.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:background="#ffffff"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     >
 <TextView
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="@string/filename"
     />

     <EditText
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:text="oppo.mp4"
         android:id="@+id/filename"
         />

     <LinearLayout
         android:orientation="horizontal"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         >
         <ImageButton
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:src="@drawable/play"
             android:id="@+id/play"
             />
          <ImageButton
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:src="@drawable/pause"
             android:id="@+id/pause"
             />
         <ImageButton
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:src="@drawable/reset"
             android:id="@+id/reset"
             />
          <ImageButton
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:src="@drawable/stop"
             android:id="@+id/stop"
             />
     </LinearLayout>

     <SurfaceView
         android:layout_width="fill_parent"
         android:layout_height="240dip"
         android:id="@+id/surfaceView"
         />
 </LinearLayout>

数据文件values/strings.xml

 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <string name="hello">Hello World, PlayActivity!</string>
     <string name="app_name">视频播放器</string>
     <string name="filename">视频文件</string>
     <string name="sdcarderror">SDCard不存在</string>
 </resources>

Activity

 package com.android.media;

 import java.io.File;
 import java.io.IOException;

 import android.app.Activity;
 import android.media.AudioManager;
 import android.media.MediaPlayer;
 import android.os.Bundle;
 import android.os.Environment;
 import android.util.Log;
 import android.view.SurfaceHolder;
 import android.view.SurfaceView;
 import android.view.View;
 import android.widget.EditText;
 import android.widget.ImageButton;
 import android.widget.Toast;

 public class PlayerActivity extends Activity {
     private static final String TAG = "PlayerActivity";
     private EditText filenameText;
     private MediaPlayer mediaPlayer;
     private SurfaceView surfaceView;
     private String filename;
     private int position;

     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);

         filenameText = (EditText)this.findViewById(R.id.filename);

         surfaceView = (SurfaceView) this.findViewById(R.id.surfaceView);
         surfaceView.getHolder().setFixedSize(176, 144);//设置分辨率
         surfaceView.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
         surfaceView.getHolder().addCallback(new SurfaceCallback());

         mediaPlayer = new MediaPlayer();
         ButtonClickListener listener = new ButtonClickListener();
         ImageButton playButton = (ImageButton)this.findViewById(R.id.play);
         ImageButton pauseButton = (ImageButton)this.findViewById(R.id.pause);
         ImageButton resetButton = (ImageButton)this.findViewById(R.id.reset);
         ImageButton stopButton = (ImageButton) this.findViewById(R.id.stop);
         playButton.setOnClickListener(listener);
         pauseButton.setOnClickListener(listener);
         resetButton.setOnClickListener(listener);
         stopButton.setOnClickListener(listener);
     }

     private final class SurfaceCallback implements SurfaceHolder.Callback{
         @Override
         public void surfaceCreated(SurfaceHolder holder) {
             if(position>0 && filename!=null){
                 try {
                     play();
                     mediaPlayer.seekTo(position);
                     position = 0;
                 } catch (IOException e) {
                     Log.e(TAG, e.toString());
                 }
             }
         }
         @Override
         public void surfaceChanged(SurfaceHolder holder, int format, int width,
                 int height) {
         }
         @Override
         public void surfaceDestroyed(SurfaceHolder holder) {
             if(mediaPlayer.isPlaying()){
                 position = mediaPlayer.getCurrentPosition();
                 mediaPlayer.stop();
             }
         }
     }

     private final class ButtonClickListener implements View.OnClickListener{
         @Override
         public void onClick(View v) {
             if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
                 Toast.makeText(PlayerActivity.this, R.string.sdcarderror, 1).show();
                 return;
             }
             filename = filenameText.getText().toString();
             try {
                 switch (v.getId()) {
                 case R.id.play:
                     play();
                     break;

                 case R.id.pause:
                     if(mediaPlayer.isPlaying()){
                         mediaPlayer.pause();
                     }else{
                         mediaPlayer.start();
                     }
                     break;
                 case R.id.reset:
                     if(mediaPlayer.isPlaying()){
                         mediaPlayer.seekTo(0);
                     }else{
                         play();
                     }
                     break;
                 case R.id.stop:
                     if(mediaPlayer.isPlaying()) mediaPlayer.stop();
                     break;
                 }
             } catch (Exception e) {
                 Log.e(TAG, e.toString());
             }
         }
     }

     private void play() throws IOException {
         File videoFile = new File(Environment.getExternalStorageDirectory(), filename);
         mediaPlayer.reset();//重置为初始状态
         mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
         /* 设置Video影片以SurfaceHolder播放 */
         mediaPlayer.setDisplay(surfaceView.getHolder());
         mediaPlayer.setDataSource(videoFile.getAbsolutePath());
         mediaPlayer.prepare();//缓冲
         mediaPlayer.start();//播放
     }
 }