android之VideoView和视频播放View的扩展

1.概念及扩展
　　VideoView 是android 系统提供的一个媒体播放显示和控制的控件。其结构层次如下：
　　原型：VideoView extends SurfaceView implements MediaController.MediaPlayerControl
　　类结构：
　　　　　　java.lang.Object
　　　　　　　　↳ android.view.View
　　　　　　　　　　↳ android.view.SurfaceView
　　　　　　　　　　　　↳ android.widget.VideoView
　　通过VideoView 的原型可知：如果构建更为复杂和有特色个性的视频View，需要继承SurfaceView 和实现MediaPlayerControl接口。其中SurfaceView 为显示提供支持，MediaPlayerControl则为媒体控制提供了支持。
2.案例
1)VideoView案例
(我们没有管理MediaPalyer的各种状态，这些状态都让VideoView给封装了，并且，当VideoView创建的时候，MediaPalyer对象将会创建，当VideoView对象销毁的时候，MediaPlayer对象将会释放。)
布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">
<VideoView android:id="@+id/video_view" android:layout_width="match_parent" android:layout_height="match_parent"
    android:layout_centerInParent="true" />
</LinearLayout>
主程序：
public class VideoPlayer extends Activity implements MediaPlayer.OnErrorListener, MediaPlayer.OnCompletionListener {
    public static final String TAG = "VideoPlayer";
    private VideoView mVideoView;
    private Uri mUri;
    private int mPositionWhenPaused = -1;

private MediaController mMediaController;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

setContentView(R.layout.main);

//Set the screen to landscape.
this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

mVideoView = (VideoView)findViewById(R.id.video_view);

//Video file
mUri = Uri.parse(Environment.getExternalStorageDirectory() + "/1.3gp");

        //Create media controller，组件可以控制视频的播放，暂停，回复，seek等操作，不需要你实现
        mMediaController = new MediaController(this);
        mVideoView.setMediaController(mMediaController);
    }

    public void onStart() {
        // Play Video
        mVideoView.setVideoURI(mUri);
        mVideoView.start();

super.onStart();
}

    public void onPause() {
        // Stop video when the activity is pause.
        mPositionWhenPaused = mVideoView.getCurrentPosition();
        mVideoView.stopPlayback();

super.onPause();
}

    public void onResume() {
        // Resume video player
        if(mPositionWhenPaused >= 0) {
            mVideoView.seekTo(mPositionWhenPaused);
            mPositionWhenPaused = -1;
        }

super.onResume();
}

    public boolean onError(MediaPlayer player, int arg1, int arg2) {
        return false;
    }

    public void onCompletion(MediaPlayer mp) {
        this.finish();
    }
}
2)自定义VideoView
和VideoView实现类似，继承了SurfaceView并且实现了MediaPlayerControl。
public class CustomerVideoView extends SurfaceView implements
        MediaPlayerControl {
    private static String TAG = "customer.videoplayer";
    private boolean pause;
    private boolean seekBackward;
    private boolean seekForward;
    private Uri videoUri;
    private MediaPlayer mediaPlayer;
    private Context context;
    private OnPreparedListener onPreparedListener;
    private int videoWidth;
    private int videoHeight;
    private MediaController mediaController;
    protected SurfaceHolder surfaceHolder;
    private Callback surfaceHolderCallback = new SurfaceHolder.Callback() {
        public void surfaceChanged(SurfaceHolder holder, int format, int w,
                int h) {
        }
        public void surfaceCreated(SurfaceHolder holder) {
            surfaceHolder = holder;
            if (mediaPlayer != null) {
                mediaPlayer.setDisplay(surfaceHolder);
                resume();
            } else {
                openVideo();
            }
        }
        public void surfaceDestroyed(SurfaceHolder holder) {
            surfaceHolder = null;
            if (mediaController != null) {
                mediaController.hide();
            }
            release(true);
        }
    };
    private void release(boolean cleartargetstate) {
        if (mediaPlayer != null) {
            mediaPlayer.reset();
            mediaPlayer.release();
            mediaPlayer = null;

补充：移动开发 , Android ,