多数人都用过 ThumbnailUtils.createVideoThumbnail() 方法，该方法在 2.x 系统下可用，API Level > 14 时却只能返回 null，以下为解决该问题方案：

重写 createVideoThumbnail() 方法，如下

    @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
    private Bitmap createVideoThumbnail(String url, int width, int height) {
        Bitmap bitmap = null;
        MediaMetadataRetriever retriever = new MediaMetadataRetriever();
        int kind = MediaStore.Video.Thumbnails.MINI_KIND;
        try {
            if (Build.VERSION.SDK_INT >= 14) {
                retriever.setDataSource(url, new HashMap<String, String>());
            } else {
                retriever.setDataSource(url);
            }
            bitmap = retriever.getFrameAtTime();
        } catch (IllegalArgumentException ex) {
            // Assume this is a corrupt video file
        } catch (RuntimeException ex) {
            // Assume this is a corrupt video file.
        } finally {
            try {
                retriever.release();
            } catch (RuntimeException ex) {
                // Ignore failures while cleaning up.
            }
        }
        if (kind == MediaStore.Images.Thumbnails.MICRO_KIND && bitmap != null) {
            bitmap = ThumbnailUtils.extractThumbnail(bitmap, width, height,
                    ThumbnailUtils.OPTIONS_RECYCLE_INPUT);
        }
        return bitmap;
    }

调用该方法并给 ImageView 设置

        String urlVideo="http://mvvideo2.meitudata.com/5785a7e3e6a1b824.mp4";
        ImageView iv_test = (ImageView) findViewById(R.id.iv_test);
        iv_test.setImageBitmap(createVideoThumbnail(urlVideo,200,200));