Android 音视频开发 - VideoView
Android 音视频开发 - VideoView
本篇文章主要介绍下Android 中的VideoView.
1: VideoView简介
VideoView是一个用于播放视频的视图组件,可以方便地在应用程序中播放本地或网络上的视频文件。
VideoView可以直接在布局文件中使用,也可以在代码中动态创建。
它封装了MediaPlayer和SurfaceView,提供了简单的接口来控制视频的播放和显示。
它提供了一系列方法来控制视频的播放、暂停、停止等操作,并且支持全屏播放和视频控制器的显示。
VideoView播放视频非常简单,只需要指定视频的URL或本地路径.
2: 使用
以下是VideoView的简单使用:
2.1 布局
在XML布局文件中添加VideoView组件.
2.2 设置视频源
代码如下:
videoView = findViewById(R.id.videoview); videoView.setVideoPath("sdcard/test.mp4");
除了setVideoPath外,我们还可以调用:
- setVideoURI(Uri uri)
- setVideoURI(Uri uri, Map headers)
当然不管是setVideoPath或者setVideoURI实际都是执行的setVideoURI(Uri uri, Map headers).
源码如下:
/** * Sets video path. * * @param path the path of the video. */ public void setVideoPath(String path) { setVideoURI(Uri.parse(path)); } /** * Sets video URI. * * @param uri the URI of the video. */ public void setVideoURI(Uri uri) { setVideoURI(uri, null); }
2.3 播放视频
videoView.start();
我们可以看下start()的源码:
@Override public void start() { if (isInPlaybackState()) { mMediaPlayer.start(); mCurrentState = STATE_PLAYING; } mTargetState = STATE_PLAYING; }
可以看到实际上调用mMediaPlayer.start();另外设置了当前的状态为STATE_PLAYING.
这里直接调用了mMediaPlayer.start();那mMediaPlayer是什么时机初始化的呢?
查看源码可以看到:
private void openVideo() { if (mUri == null || mSurfaceHolder == null) { // not ready for playback just yet, will try again later return; } // we shouldn't clear the target state, because somebody might have // called start() previously release(false); if (mAudioFocusType != AudioManager.AUDIOFOCUS_NONE) { // TODO this should have a focus listener mAudioManager.requestAudioFocus(null, mAudioAttributes, mAudioFocusType, 0 /*flags*/); } try { mMediaPlayer = new MediaPlayer(); // TODO: create SubtitleController in MediaPlayer, but we need // a context for the subtitle renderers final Context context = getContext(); final SubtitleController controller = new SubtitleController( context, mMediaPlayer.getMediaTimeProvider(), mMediaPlayer); controller.registerRenderer(new WebVttRenderer(context)); controller.registerRenderer(new TtmlRenderer(context)); controller.registerRenderer(new Cea708CaptionRenderer(context)); controller.registerRenderer(new ClosedCaptionRenderer(context)); mMediaPlayer.setSubtitleAnchor(controller, this); if (mAudioSession != 0) { mMediaPlayer.setAudioSessionId(mAudioSession); } else { mAudioSession = mMediaPlayer.getAudioSessionId(); } mMediaPlayer.setOnPreparedListener(mPreparedListener); mMediaPlayer.setOnVideoSizeChangedListener(mSizeChangedListener); mMediaPlayer.setOnCompletionListener(mCompletionListener); mMediaPlayer.setOnErrorListener(mErrorListener); mMediaPlayer.setOnInfoListener(mInfoListener); mMediaPlayer.setOnBufferingUpdateListener(mBufferingUpdateListener); mCurrentBufferPercentage = 0; mMediaPlayer.setDataSource(mContext, mUri, mHeaders); mMediaPlayer.setDisplay(mSurfaceHolder); mMediaPlayer.setAudioAttributes(mAudioAttributes); mMediaPlayer.setScreenOnWhilePlaying(true); mMediaPlayer.prepareAsync(); for (Pair pending: mPendingSubtitleTracks) { try { mMediaPlayer.addSubtitleSource(pending.first, pending.second); } catch (IllegalStateException e) { mInfoListener.onInfo( mMediaPlayer, MediaPlayer.MEDIA_INFO_UNSUPPORTED_SUBTITLE, 0); } } // we don't set the target state here either, but preserve the // target state that was there before. mCurrentState = STATE_PREPARING; attachMediaController(); } catch (IOException ex) { Log.w(TAG, "Unable to open content: " + mUri, ex); mCurrentState = STATE_ERROR; mTargetState = STATE_ERROR; mErrorListener.onError(mMediaPlayer, MediaPlayer.MEDIA_ERROR_UNKNOWN, 0); return; } catch (IllegalArgumentException ex) { Log.w(TAG, "Unable to open content: " + mUri, ex); mCurrentState = STATE_ERROR; mTargetState = STATE_ERROR; mErrorListener.onError(mMediaPlayer, MediaPlayer.MEDIA_ERROR_UNKNOWN, 0); return; } finally { mPendingSubtitleTracks.clear(); } }
可以看到openVideo()
- release()方法释放正在播放的视频.
- 初始化mMediaPlayer,传入Uri,设置状态 STATE_PREPARING。
- attachMediaController()绑定MediaPlayer与VideoView。
最后openVideo()则是在setVideoURI(Uri uri, Map headers)内调用。
这样其实已经可以播放指定的视频了。
下面的方法可选。
2.4 MediaController控制器
MediaController是一个用于控制媒体播放器的视图组件。
MediaController的使用步骤如下:
- 创建一个MediaController对象:MediaController mediaController = new MediaController(context);
- 将MediaController与媒体播放器组件关联:mediaController.setMediaPlayer(mediaPlayer);
- 将MediaController添加到布局中:layout.addView(mediaController);
videoView.setMediaController(new MediaController(this)); videoView.start().
直接调用setMediaController,运行后我们可以看到与之前直接调用start()的区别就是多了个控制器的显示。其中包含一组常用的媒体控制按钮,如播放/暂停、快进/快退、前进/后退等,并且可以与MediaPlayer或VideoView等媒体播放器组件进行关联.
我们可以看下源码:
public void setMediaController(MediaController controller) { if (mMediaController != null) { mMediaController.hide(); } mMediaController = controller; attachMediaController(); }
可以看到做的操作如下:
- 如果存在mMediaController,则调用hide方法。
- 对mMediaController赋值
- attachMediaController