019_01播放视频之SurfaceView

　　MediaPlayer主要用于播放音频，因此它没有提供图像输出界面，所以要借助于SurfaceView来显示MediaPalyer播放的图像输出。

　　SurfaceHolder是一个接口，其作用就像一个关于Surface的监听器。提供访问和控制SurfaceView背后的Surface 相关的方法（providingaccess and control over this SurfaceView's underlying surface），它通过三个回调方法，让我们可以感知到Surface的创建、销毁或者改变。在SurfaceView中有一个方法getHolder，可以很方便地获得SurfaceView所对应的Surface所对应的SurfaceHolder

  1 package com.example.day19_01videoplayer;
  2 
  3 import java.io.IOException;
  4 import android.app.Activity;
  5 import android.media.AudioManager;
  6 import android.media.MediaPlayer;
  7 import android.os.Bundle;
  8 import android.os.Environment;
  9 import android.view.SurfaceHolder;
 10 import android.view.SurfaceView;
 11 import android.view.View;
 12 
 13 public class MainActivity extends Activity {
 14 
 15     private SurfaceHolder holder;
 16     private MediaPlayer mediaPlayer;
 17     private final int STATE_IDLE = 0;
 18     private final int STATE_PLAYING = 1;
 19     private final int STATE_PAUSED = 2;
 20     private final int STATE_STOP =3;
 21 
 22     private int current_state = STATE_IDLE;
 23     private String path;
 24     
 25     @Override
 26     protected void onCreate(Bundle savedInstanceState) {
 27         super.onCreate(savedInstanceState);
 28         setContentView(R.layout.activity_main);
 29         
 30         SurfaceView surfaceView = (SurfaceView) findViewById(R.id.sf_video);
 31         holder = surfaceView.getHolder();
 32         path = Environment.getExternalStorageDirectory().getAbsolutePath()+"/sirendingzhi.mp4";
 33 
 34     }
 35 
 36      public void play(View v){
 37          
 38          if (mediaPlayer==null) {
 39              mediaPlayer = new MediaPlayer();             
 40          }
 41          
 42         if (current_state==STATE_PAUSED) {
 43             mediaPlayer.start();    
 44         } 
 45          
 46         if (current_state==STATE_IDLE||current_state==STATE_STOP) {
 47             mediaPlayer.reset();
 48              try {
 49                 mediaplay();    
 50             } catch (Exception e) {
 51                 // TODO Auto-generated catch block
 52                 e.printStackTrace();
 53             }
 54         } 
 55         
 56         current_state=STATE_PLAYING;
 57 
 58          
 59      }
 60 
 61     private void mediaplay() throws IOException {
 62         mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
 63         mediaPlayer.setDisplay(holder); 
 64         mediaPlayer.setDataSource(path);        
 65         mediaPlayer.prepare();
 66         mediaPlayer.start();
 67 
 68     }
 69      
 70      public void pause(View v){ 
 71          if (current_state==STATE_PLAYING) {
 72                 mediaPlayer.pause();
 73                 current_state=STATE_PAUSED;
 74             }
 75      }
 76      
 77      public void stop(View v){
 78          if (mediaPlayer!=null) {
 79                if (current_state==STATE_PLAYING||current_state==STATE_PAUSED) {
 80                     mediaPlayer.stop();
 81                      mediaPlayer.reset();
 82                      current_state=STATE_STOP;
 83                }    
 84         }
 85          
 86      }
 87      
 88      public void replay(View v){
 89          
 90           if (current_state!=STATE_IDLE) {
 91               if (current_state==STATE_STOP) {
 92                     
 93                }
 94              
 95                if (current_state==STATE_PLAYING||current_state==STATE_PAUSED) {
 96                     mediaPlayer.stop();
 97                     mediaPlayer.reset();    
 98                }    
 99                  try {
100                     mediaplay();    
101                } catch ( Exception e) {
102                     // TODO Auto-generated catch block
103                     e.printStackTrace();
104                 }        
105                   current_state=STATE_PLAYING;
106         }          
107      }
108      
109      @Override
110     protected void onDestroy() {
111         // TODO Auto-generated method stub
112         super.onDestroy();
113         
114         if (mediaPlayer!=null) {
115             mediaPlayer.stop();
116             mediaPlayer.reset();
117             mediaPlayer.release();
118         }    
119     }     
120 }

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:paddingBottom="@dimen/activity_vertical_margin"
 6     android:paddingLeft="@dimen/activity_horizontal_margin"
 7     android:paddingRight="@dimen/activity_horizontal_margin"
 8     android:paddingTop="@dimen/activity_vertical_margin"
 9     tools:context="com.example.day19_01videoplayer.MainActivity" 
10     android:orientation="vertical">
11 
12     <LinearLayout 
13         android:layout_width="fill_parent"
14         android:layout_height="wrap_content"
15         android:orientation="horizontal" >
16         <Button
17             android:layout_width="wrap_content"
18             android:layout_height="wrap_content"
19             android:text="播放"
20             android:onClick="play" />
21         <Button
22             android:layout_width="wrap_content"
23             android:layout_height="wrap_content"
24             android:text="暂停"
25             android:onClick="pause" />
26         <Button
27             android:layout_width="wrap_content"
28             android:layout_height="wrap_content"
29             android:text="停止"
30             android:onClick="stop" />
31         <Button
32             android:layout_width="wrap_content"
33             android:layout_height="wrap_content"
34             android:text="重播"
35             android:onClick="replay" />
36     </LinearLayout>
37     
38     <SurfaceView 
39         android:id="@+id/sf_video"
40         android:layout_width="fill_parent"
41         android:layout_height="fill_parent"
42         />
43  
44 </LinearLayout >

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