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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; } } public void resume() { if (surfaceHolder == null) { return; } if (mediaPlayer != null) { return; } openVideo(); } public CustomerVideoView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); this.context = context; this.initVideoView(); } public CustomerVideoView(Context context, AttributeSet attrs) { super(context, attrs); this.context = context; this.initVideoView(); } public CustomerVideoView(Context context) { super(context); this.context = context; this.initVideoView(); } @Override public boolean canPause() { return this.pause; } @Override public boolean canSeekBackward() { return this.seekBackward; } @Override public boolean canSeekForward() { return this.seekForward; } @Override public int getBufferPercentage() { return 0; } @Override public int getCurrentPosition() { return mediaPlayer!=null?mediaPlayer.getCurrentPosition():0; } @Override public int getDuration() { return mediaPlayer!=null?mediaPlayer.getDuration():0; } @Override public boolean isPlaying() { return false; } @Override public void pause() { } @Override public void seekTo(int mSec) { } @Override public void start() { } public void setVideoURI(Uri uri) { this.videoUri = uri; openVideo(); requestLayout(); invalidate(); } private void openVideo() { this.mediaPlayer = new MediaPlayer(); try { this.mediaPlayer.setDataSource(this.context, this.videoUri); } catch (Exception e) { Log.e(TAG, e.getMessage()); throw new RuntimeException(e); } this.mediaPlayer.prepareAsync(); this.mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); this.mediaPlayer.setOnPreparedListener(onPreparedListener); attachMediaController(); } private void attachMediaController() { if (mediaPlayer != null && mediaController != null) { mediaController.setMediaPlayer(this); View anchorView = this.getParent() instanceof View ? (View) this .getParent() : this; mediaController.setAnchorView(anchorView); mediaController.setEnabled(true); } } public void setMediaController(MediaController controller) { if (mediaController != null) { mediaController.hide(); } mediaController = controller; attachMediaController(); } public void setOnPreparedListener(OnPreparedListener onPreparedListener) { this.onPreparedListener = onPreparedListener; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int width = getDefaultSize(videoWidth, widthMeasureSpec); int height = getDefaultSize(videoHeight, heightMeasureSpec); if (videoWidth > 0 && videoHeight > 0) { if (videoWidth * height > width * videoHeight) { height = width * videoHeight / videoWidth; } else if (videoWidth * height < width * videoHeight) { width = height * videoWidth / videoHeight; } } Log.i(TAG, "setting size: " + width + ‘x’ + height); setMeasuredDimension(width, height); } private void initVideoView() { videoWidth = 0; videoHeight = 0; getHolder().addCallback(surfaceHolderCallback); getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); setFocusable(true); setFocusableInTouchMode(true); requestFocus(); } }
一般情况下，android界面的绘制和更新，要交给主ui线程来操作，通过Handler机制。但是播放视频，需要比较优先和实时的改变和绘制界面。android提供了使用单独线程绘制UI的机制，就是SurfaceView。使用SurfaceView，需要实现SurfaceHolder.Callback接口：
开发者不能直接操作Surface实例，要通过SurfaceHandler，在SurfaceView中可以通过getHandler方法获取到SurfaceHandler实例。 SurfaceHander有一些类型，用来标识Surface实例界面数据来源，可以通过setType来操作：
CustomerVideoView的构造方法，使用超类的构造方法。都会执行initVideoView()方法用来初始化界面和参数。另外一个主要的内容是openVideo()方法：
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原文地址：http://www.cnblogs.com/chengzhengfu/p/4579041.html
