android获取在线视频略缩图

文章参考：

http://blog.csdn.net/u011198764/article/details/40540607

提取了所需文件和代码，留作备忘。

/** * @param url *            要加载资源的地址 * @param imageView *            显示略缩图的ImageView控件 */public void loadVideoBitmap(String url, ImageView imageView) {// 缓存中的BitmapBitmap bitmap = ImageDownloader.getBitmapFromCache(url);// 缓存中不存在就从网络上获取资源if (bitmap == null) {forceDownload(url, imageView);} else {imageView.setVisibility(View.VISIBLE);ImageDownloader.cancelPotentialDownload(url, imageView);imageView.setImageBitmap(adjustPhotoRotation(ThumbnailUtils.extractThumbnail(bitmap,100, 100),90));}}/** * @param url *            资源地址 * @param imageView *            加载略缩图的ImageView控件 */private void forceDownload(String url, ImageView imageView) {// State sanity: url is guaranteed to never be null in// DownloadedDrawable and cache keys.if (url == null) {imageView.setImageDrawable(null);return;}// 判断是否需要下载if (ImageDownloader.cancelPotentialDownload(url, imageView)) {imageView.setVisibility(View.VISIBLE);BitmapWorkerTask task = new BitmapWorkerTask(imageView);Bitmap defaultBimap = BitmapFactory.decodeStream(mContext.getResources().openRawResource(R.drawable.image_failed1));AsyncDrawable downloadedDrawable = new AsyncDrawable(mContext.getResources(), defaultBimap, task);imageView.setImageDrawable(downloadedDrawable);imageView.setMinimumHeight(100);task.execute(url);}}class BitmapWorkerTask extends AsyncTask<String, Void, Bitmap> {private final WeakReference<ImageView> imageViewReference;private String url;public BitmapWorkerTask(ImageView imageView) {// Use a WeakReference to ensure the ImageView can be garbage// collectedimageViewReference = new WeakReference<ImageView>(imageView);}@Overrideprotected Bitmap doInBackground(String... params) {url = params[0];// 获取在线视频的帧的图像，返回BitmapBitmap tempBitmap = getVideoThumbnail(url);return tempBitmap;}@Overrideprotected void onPostExecute(Bitmap bitmap) {if (isCancelled()) {bitmap = null;}ImageDownloader.addBitmapToCache(url, bitmap);if (imageViewReference != null && bitmap != null) {final ImageView imageView = imageViewReference.get();final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView);// 判断当前的异步对象是否与ImageView所在的异步对象是否相等，以此来防止加载错乱if (this == bitmapWorkerTask && imageView != null) {//imageView.setTag(bitmap);imageView.setImageBitmap(adjustPhotoRotation(ThumbnailUtils.extractThumbnail(bitmap, 100, 100),90));}}}}public Bitmap getVideoThumbnail(String videoUrl) {Bitmap generateBitmap = null;FFmpegMediaMetadataRetriever fmmr = new FFmpegMediaMetadataRetriever();try {fmmr.setDataSource(videoUrl);generateBitmap = fmmr.getFrameAtTime();if (generateBitmap != null) {Bitmap b2 = fmmr.getFrameAtTime(4000000,FFmpegMediaMetadataRetriever.OPTION_CLOSEST_SYNC);if (b2 != null) {// 获取到了Bitmap之后用android自带的ThumbnailUtils获取自定义大小的略缩图generateBitmap = ThumbnailUtils.extractThumbnail(b2, 640,640, ThumbnailUtils.OPTIONS_RECYCLE_INPUT);}}} catch (IllegalArgumentException ex) {ex.printStackTrace();} finally {fmmr.release();}if (generateBitmap != null) {return generateBitmap;}return null;}static class AsyncDrawable extends BitmapDrawable {private final WeakReference<BitmapWorkerTask> bitmapWorkerTaskReference;public AsyncDrawable(Resources res, Bitmap bitmap,BitmapWorkerTask bitmapWorkerTask) {super(res, bitmap);bitmapWorkerTaskReference =new WeakReference<BitmapWorkerTask>(bitmapWorkerTask);}public BitmapWorkerTask getBitmapWorkerTask() {return bitmapWorkerTaskReference.get();}}private static BitmapWorkerTask getBitmapWorkerTask(ImageView imageView) {if (imageView != null) {final Drawable drawable = imageView.getDrawable();if (drawable instanceof AsyncDrawable) {final AsyncDrawable asyncDrawable = (AsyncDrawable) drawable;return asyncDrawable.getBitmapWorkerTask();}}return null;}/** * 旋转图片 *  * @param bm * @param orientationDegree * @return */private Bitmap adjustPhotoRotation(Bitmap bm, final int orientationDegree) {Matrix m = new Matrix();m.setRotate(orientationDegree, (float) bm.getWidth() / 2,(float) bm.getHeight() / 2);float targetX, targetY;if (orientationDegree == 90) {targetX = bm.getHeight();targetY = 0;} else {targetX = bm.getHeight();targetY = bm.getWidth();}final float[] values = new float[9];m.getValues(values);float x1 = values[Matrix.MTRANS_X];float y1 = values[Matrix.MTRANS_Y];m.postTranslate(targetX - x1, targetY - y1);Bitmap bm1 = Bitmap.createBitmap(bm.getHeight(), bm.getWidth(),Bitmap.Config.ARGB_8888);Paint paint = new Paint();Canvas canvas = new Canvas(bm1);canvas.drawBitmap(bm, m, paint);return bm1;}