android获取视频第一帧并保存到本地

public static Bitmap retriveVideoFrameFromVideo(String videoPath)throws Throwable
    {
        Bitmap bitmap = null;
        MediaMetadataRetriever mediaMetadataRetriever = null;
        try
        {
            mediaMetadataRetriever = new MediaMetadataRetriever();
            if (Build.VERSION.SDK_INT >= 14)
                mediaMetadataRetriever.setDataSource(videoPath, new HashMap<String, String>());
            else
                mediaMetadataRetriever.setDataSource(videoPath);
            //   mediaMetadataRetriever.setDataSource(videoPath);
            bitmap = mediaMetadataRetriever.getFrameAtTime(4000, MediaMetadataRetriever.OPTION_CLOSEST);
        }
        catch (Exception e)
        {
            e.printStackTrace();
            throw new Throwable("Exception in retriveVideoFrameFromVideo(String videoPath)"+ e.getMessage());
        }
        finally
        {
            if (mediaMetadataRetriever != null)
            {
                mediaMetadataRetriever.release();
            }
        }
        return bitmap;
    }

public static String save(Bitmap bmp)
    {
        File appDir = new File(Environment.getExternalStorageDirectory() + File.separator + Environment.DIRECTORY_DCIM + File.separator + "tempFolder");
        if (!appDir.exists())appDir.mkdirs();

        String fileName = "temp" + System.currentTimeMillis() + ".jpg";
        File file = new File(appDir, fileName);
        try
        {
            FileOutputStream fos = new FileOutputStream(file);
            bmp.compress(Bitmap.CompressFormat.JPEG, 100, fos);
            fos.flush();
            fos.close();
            return Uri.fromFile(file).getPath();
        } catch (FileNotFoundException e)
        {
            e.printStackTrace();
        } catch (IOException e)
        {
            e.printStackTrace();
        }
        return null;
    }