Androidx学习笔记（78）--- 视频播放器（MediaPlayer+SurfaceView）

SurfaceView

• 双缓冲技术
• 该组件是重量级组件:占用资源比较多
  • 只要不可见，就不会创建，可见时，才会创建
  • 只要不可见，就会销毁

FFMPEG

• 开源免费的音视频编解码器

Vitamio

• 封装了FFMPEG的视频播放框架
• 对外提供的api全部都是javaApi

SurfaceView

• 对画面的实时更新要求较高
• 双缓冲技术：内存中有两个画布，A画布显示至屏幕，B画布在内存中绘制下一帧画面，绘制完毕后B显示至屏幕，A在内存中继续绘制下一帧画面

• 播放视频也是用MediaPlayer，不过跟音频不同，要设置显示在哪个SurfaceView

  SurfaceView sv = (SurfaceView) findViewById(R.id.sv);SurfaceHolder sh = sv.getHolder();MediaPlayer player = new MediaPlayer();player.reset();try {    player.setDataSource("sdcard/2.3gp");    player.setDisplay(sh);    player.prepare();} catch (Exception e) {    e.printStackTrace();}player.start();

• SurfaceView是重量级组件，可见时才会创建

• 给SurfaceHolder设置CallBack，类似于侦听，可以知道SurfaceView的状态

  sh.addCallback(new Callback() {    //SurfaceView销毁时调用    @Override    public void surfaceDestroyed(SurfaceHolder holder) {        // TODO Auto-generated method stub    }    //SurfaceView创建时调用    @Override    public void surfaceCreated(SurfaceHolder holder) {        // TODO Auto-generated method stub    }    @Override    public void surfaceChanged(SurfaceHolder holder, int format, int width,            int height) {        // TODO Auto-generated method stub    }});

• SurfaceView一旦不可见，就会被销毁，一旦可见，就会被创建，销毁时停止播放，再次创建时再开始播放

布局文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >
 
    <SurfaceView
        android:id="@+id/sv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />
 
</RelativeLayout>

java代码

public class MainActivity extends Activity {
private MediaPlayer player;
static int currentPosition;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SurfaceView sv = (SurfaceView) findViewById(R.id.sv);
//拿到surfaceview的控制器
final SurfaceHolder sh = sv.getHolder();
        //使用固定的等待时间 让SurfaceView可见---不合理的
//Thread t = new Thread(){
//@Override
//public void run() {
//// TODO Auto-generated method stub
//try {
//sleep(200);
//} catch (InterruptedException e) {
//// TODO Auto-generated catch block
//e.printStackTrace();
//}
//runOnUiThread(new Runnable() {
//@Override
//public void run() {
//MediaPlayer player = new MediaPlayer();
//player.reset();
//try {
//player.setDataSource("sdcard/2.3gp");
//player.setDisplay(sh);
//player.prepare();
//player.start();
//} catch (Exception e) {
//// TODO Auto-generated catch block
//e.printStackTrace();
//} 
//
//}
//});
//
//}
//};
//t.start();
         
        //使用监听的方式 让SurfaceView可见
sh.addCallback(new Callback() {
//surfaceView销毁时调用
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
//每次surfaceview销毁时，同时停止播放视频
if(player != null){
currentPosition = player.getCurrentPosition();
player.stop();
player.release();
player = null;
}
}
//surfaceView创建时调用
@Override
public void surfaceCreated(SurfaceHolder holder) {
//每次surfaceView创建时才去播放视频
if(player == null){
player = new MediaPlayer();
player.reset();
try {
player.setDataSource("sdcard/2.3gp");
player.setDisplay(sh);
player.prepare();
player.start();
player.seekTo(currentPosition);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} 
}
}
//surfaceView结构改变时调用
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
});
}
 
 
}