ListAdapter中显示的Android视频缩略图

Question

我目前正在将设备上的所有视频加载到一个自定义ListAdapter中，该ListAdapter显示Video+更多内容的缩略图。我注意到，当我添加越来越多的视频时，启动速度变得越来越慢。这就是我的列表适配器的样子：

public class VideoListAdapter extends ArrayAdapter<Video> {
    private ArrayList<Video> allVideos;
    private HashMap<String, Bitmap> bitmapCache;
    public VideoListAdapter(Context context, ArrayList<Video> videos) {
        super(context, R.layout.video_list_item, videos);
        this.allVideos = videos;
        /* Cache the thumbnails */
        setUpBitmaps();
    }
    private void setUpBitmaps() {
        bitmapCache = new HashMap<String, Bitmap>(allVideos.size());
        for(Video video : allVideos){
            bitmapCache.put(video.getDATA(), ThumbnailUtils.createVideoThumbnail(video.getDATA(), Thumbnails.MICRO_KIND));
        }
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row;
        if (convertView == null) {
            LayoutInflater inflater = LayoutInflater.from(getContext());
            row = inflater.inflate(R.layout.video_list_item, null);
        } else {
            row = convertView;
        }
        Video tmpVideo = allVideos.get(position);
        String TITLE = tmpVideo.getTITLE();
        long vidDur = Long.valueOf(tmpVideo.getDURATION());
        String DURATION = String.format(Locale.getDefault(),"%02d:%02d", 
                TimeUnit.MILLISECONDS.toMinutes(vidDur) -  
                TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(vidDur)), 
                TimeUnit.MILLISECONDS.toSeconds(vidDur) - 
                TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(vidDur)));
        String filepath = tmpVideo.getDATA();
        Bitmap thumbnail = bitmapCache.get(filepath);
        TextView tvTitle = (TextView) row.findViewById(R.id.tvListItemVideoTitle);
        TextView tvDuration = (TextView) row.findViewById(R.id.tvListItemVideoDuration);
        ImageView ivThumbnail = (ImageView) row.findViewById(R.id.ivListItemVideoThumbnail);
        tvTitle.setText(TITLE);
        tvDuration.setText(DURATION);
        if(thumbnail != null){
            ivThumbnail.setImageBitmap(thumbnail);
        }
        return row;
    }
}

应该如何加载缩略图以减少加载列表适配器所需的时间？目前在我的设备上，显示适配器的活动需要3-4秒，我只有大约15个视频。

如有任何建议，我们将不胜感激。

Marcus

Answer 1

不要在列表视图中显示视频，而是通过传递视频路径来获取视频的缩略图，并将其显示在listview中。。使用此代码可以获取缩略图。也可以使用lazylist来正确显示图像。

Bitmap thumb = ThumbnailUtils.createVideoThumbnail(path,
MediaStore.Images.Thumbnails.MINI_KIND);

Answer 2

You can use lazyloading for this,LazyLoading will make your list scroll fast.Follow this library it will help:
https://github.com/nostra13/Android-Universal-Image-Loader
Steps of using lazy loading :
1.)Download jar file from this link:
http://www.java2s.com/Code/Jar/u/Downloaduniversalimageloader161withsrcjar.htm
2.)Create Application File :
import android.app.Application;
import com.nostra13.universalimageloader.cache.memory.impl.WeakMemoryCache;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
import com.nostra13.universalimageloader.core.assist.ImageScaleType;
import com.nostra13.universalimageloader.core.display.FadeInBitmapDisplayer;
public class MyApplication extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        // UNIVERSAL IMAGE LOADER SETUP
        DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder()
                .cacheOnDisc(true).cacheInMemory(true)
                .imageScaleType(ImageScaleType.EXACTLY)
                .displayer(new FadeInBitmapDisplayer(300)).build();
        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(
                getApplicationContext())
                .defaultDisplayImageOptions(defaultOptions)
                .memoryCache(new WeakMemoryCache())
                .discCacheSize(100 * 1024 * 1024).build();
        ImageLoader.getInstance().init(config);
        // END - UNIVERSAL IMAGE LOADER SETUP
    }
}
3.)On your activity in whcih you want to use ,write this it onCreate():
DisplayImageOptions options = new DisplayImageOptions.Builder()
                .showImageOnLoading(R.drawable.iclauncher) // resource or
                                                                // drawable
                .showImageForEmptyUri(R.drawable.iclauncher) // resource or
                // drawable
                .showImageOnFail(R.drawable.iclauncher) // resource or
                                                            // drawable
                .resetViewBeforeLoading(false) // default
                .delayBeforeLoading(1000).cacheInMemory(true) // default
                .cacheOnDisc(true) // default
                .considerExifParams(true) // default
                .imageScaleType(ImageScaleType.IN_SAMPLE_INT) // default
                .bitmapConfig(Bitmap.Config.ARGB_8888) // default
                .displayer(new SimpleBitmapDisplayer()) // default
                .handler(new Handler()) // default
                .build();
        imageLoader = ImageLoader.getInstance();
4.)on your adapter write this: 
    imageLoader.displayImage(alist.get(position).getThumbnails(),
                    holder.ivImage, options, null); // alist.get(position).getThumbnails() is the url of the thumbnail and holder.ivImage is the reference of the imageview where thumbnail is to be placed