安卓：ListAdapter例如重绘相同的内容 [英] Android: ListAdapter example redraws same content

问题描述

我用ListAdapter从这个例子：

I use a ListAdapter from this example:

<一个href=\"http://$c$c.google.com/p/au-optimizing-layouts-201/source/browse/au_optimizinglayouts/src/com/example/android/training/optimizinglayouts/OptimizedListAdapter.java?r=4\" rel=\"nofollow\">http://$c$c.google.com/p/au-optimizing-layouts-201/source/browse/au_optimizinglayouts/src/com/example/android/training/optimizinglayouts/OptimizedListAdapter.java?r=4

这个例子是不是很好，因为在列表中的元素拿得出好几次我取决于如何快速滚动。因为只有一个复用的那

The example is not very good, because elements in the list get drawn several times depending how fast I scroll. Thats because of the reuse of only one

private FakeImageLoader mFakeImageLoader;

如果FakeImageLoader.java的getImage（）将加载一个真正的形象。
需要采取哪些措施来获得这个例子中运行，并保持高性能？

If FakeImageLoader.java getImage() would load a real image. What needs to be done to get this example running and stay performant?

public class OptimizedListAdapter extends BaseAdapter{

        ...
        private FakeImageLoader mFakeImageLoader;

public OptimizedListAdapter(Context cxt)
        {
                // Cache the LayoutInflate to avoid asking for a new one each time.
                mLayoutInflater = LayoutInflater.from(cxt);
                mFakeImageLoader = new FakeImageLoader(cxt);
                ...

 public View getView(final int position, View convertView, ViewGroup parent)
        {
        // A ViewHolder keeps references to children views to avoid unneccessary calls
        // to findViewById() on each row.
        ViewHolder holder;

                // When convertView is not null, we can reuse it directly, there is no need
        // to reinflate it. We only inflate a new View when the convertView supplied
        // by ListView is null.
                if(convertView==null)
                {
                        convertView = mLayoutInflater.inflate(R.layout.listitem, null);

                        // Creates a ViewHolder and store references to the two children views
            // we want to bind data to.
            holder = new ViewHolder();
            holder.icon = (ImageView) convertView.findViewById(R.id.listitem_image);
            holder.text = (TextView) convertView.findViewById(R.id.listitem_text);
            holder.timestamp = (TextView) convertView.findViewById(R.id.listitem_timestamp);
            convertView.setTag(holder);
                }else
                {
                        holder = (ViewHolder) convertView.getTag();
                }

                //holder.icon.setImageDrawable(drawable);
                holder.text.setText(new StringBuffer(ITEM_PRE_TEXT).append(position));
                holder.timestamp.setText(""+(System.currentTimeMillis()-START_TIMESTAMP));
        holder.position = position;

        //during a fast scroll this could start 100's of threads, need a thread pool processing them!
        //see previous ImageLoader.
                new AsyncTask<ViewHolder, Void, Bitmap>() {
                        private ViewHolder v;

                        @Override
                        protected Bitmap doInBackground(ViewHolder... params) {
                                v = params[0];
                                return mFakeImageLoader.getImage();
                        }

                        @Override
                        protected void onPostExecute(Bitmap result) {
                                super.onPostExecute(result);
                                if(v.position == position)
                                {
                                        v.icon.setImageBitmap(result);
                                }
                        }

                  }.execute(holder);
                  //holder.icon.setImageBitmap(mFakeImageLoader.getImage());

                return convertView;
        }

由于塔塔

推荐答案

我用这个通用在一个应用程序图像加载器库通用映像加载库下载图像，这是比较有用的我。

I used this universal image loader library universal image loader library in one app to download images and it is more useful for me.

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