从视频 URL 获取缩略图，但在回收站视图上加载数据需要 5 秒以上答案

【问题标题】：get thumbnail from video URL but it takes more than 5 seconds to load data on recycler view从视频 URL 获取缩略图，但在回收站视图上加载数据需要 5 秒以上
【发布时间】：2019-08-17 08:20:30
【问题描述】：

我正在使用以下代码从视频 URL 获取视频列表和缩略图但在回收站视图上加载数据需要 5 秒以上。

public class VideoAsync extends AsyncTask {

    private static final String TAG = "VideoAsync";
    private VideoAdapter videoAdapter;
    private RecyclerView recyclerView;
    private List<Video> videoList;
    private Context context;

    public VideoAsync(RecyclerView recyclerView, Context context) {
        this.recyclerView = recyclerView;
        this.videoList = new ArrayList<>();
        this.context = context;
    }

    @Override
    protected Object doInBackground(Object[] objects) {

        return getAllMedia();
    }

    @Override
    protected void onPostExecute(Object o) {
        super.onPostExecute(o);
        videoAdapter = new VideoAdapter(getAllMedia(), context);
        recyclerView.setAdapter(videoAdapter);
        videoAdapter.notifyDataSetChanged();
    }

    private List<Video>  getAllMedia() {
        HashSet<Video> videoItemHashSet = new HashSet<>();
        String[] projection = { MediaStore.Video.VideoColumns.DATA ,MediaStore.Video.Media.TITLE,

MediaStore.Video.VideoColumns.DURATION}; 光标 cursor = context.getContentResolver().query(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, 投影，空，空，空）；尝试 { cursor.moveToFirst();

            do{
                Video video = new Video();

                video.setVideoPath((cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA))));
                video.setVideoTitle((cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.TITLE))));
                video.setVideoDuration(duration(cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DURATION))));
                video.setThumbnail(getThumbNail((cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA)))));
                videoItemHashSet.add(video);

            }while(cursor.moveToNext());

            cursor.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

        videoList.addAll(videoItemHashSet);
        Log.d(TAG, "getAllMedia: "+ videoList.size()) ;
        return videoList;
    }

    private static Bitmap getThumbNail(String imagePath){
        return ThumbnailUtils.createVideoThumbnail(imagePath, MediaStore.Video.Thumbnails.MINI_KIND);
    }

    private static String duration(String time){
        long duration = Long.parseLong(time);
        return  String.format("%d:%d",
                TimeUnit.MILLISECONDS.toMinutes(duration),
                TimeUnit.MILLISECONDS.toSeconds(duration) -
                        TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(duration))
        );
    }
}


//Video fragment

这里，Adapter 设置在 Videoasync 类中。公共类 VideosFragment 扩展 Fragment {

    @BindView(R.id.rv_video) RecyclerView recyclerView;

    private VideoAsync videoAsync;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_videos, container, false);
        ButterKnife.bind(this, view);
        setRecyclerView();

        return  view;
    }

    private void setRecyclerView(){
        recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
        videoAsync = new VideoAsync(recyclerView, getContext());
        videoAsync.execute();
    }
}

【问题讨论】：

检查缩略图的大小。
私有静态位图 getThumbNail(String imagePath){ return ThumbnailUtils.createVideoThumbnail(imagePath, MediaStore.Video.Thumbnails.MINI_KIND); }//这个方法需要时间从url制作缩略图
如果尺寸很大，加载会需要时间。

标签： android

【解决方案1】：

这一行可能会减慢加载过程。最坏的情况是可能会抛出OOM Exception

ThumbnailUtils.createVideoThumbnail(imagePath, MediaStore.Video.Thumbnails.MINI_KIND);

截至

video.setThumbnail(getThumbNail((cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA)))));

除非有严格的内存管理，否则始终建议仅在需要时加载位图。为了节省时间，我会让位图加载到 Glide 或任何其他类似的库中。也就是说，改为：

do{
            Video video = new Video();

            video.setVideoPath((cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA))));
            video.setVideoTitle((cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.TITLE))));
            video.setVideoDuration(duration(cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DURATION))));
            //video.setThumbnail(getThumbNail((cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA)))));
            videoItemHashSet.add(video);

        }while(cursor.moveToNext());

在recyclerView的adapter的onBindViewHolder里面，用Glide动态加载视频位图例如：

 @Override
    public void onBindViewHolder(YourAdapter.ItemViewHolder holder, int position) {
        Video v = videoItemHashset.get(position);

        Glide.with(your_context)
                .asBitmap()
                .load(Uri.fromFile(new File(v.getVideoPath())))
                .centerCrop()
                .into(holder.videoThumbnailImageView);

        holder.mPosition = position;///in case you're going to need it for playing the video at that position
    }

【讨论】：

【解决方案2】：

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(1, 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;
}`enter code here`

【讨论】：