private static class ImageAdapter extends BaseAdapter {
  private static final String[] IMAGE_URLS = Constants.IMAGES_CN;
  private LayoutInflater inflater;
  private DisplayImageOptions options;
  ImageAdapter(Context context) {
    inflater = LayoutInflater.from(context);
    options = new DisplayImageOptions.Builder()
        .showImageOnLoading(R.drawable.ic_stub)  //设置加载时显示的图片
        .showImageForEmptyUri(R.drawable.ic_empty)  //设置 Uri 为 空时显示的图片
        .showImageOnFail(R.drawable.ic_error)  //设置加载失败显示的图片
        .cacheInMemory(true)      //设置内存缓存
        .cacheOnDisk(true)          //设置磁盘缓存
        .considerExifParams(true)       //考虑相机参数
        .bitmapConfig(Bitmap.Config.RGB_565)  //设置解码参数
        .build();
  }
  @Override
  public int getCount() {
    return IMAGE_URLS.length;
  }
  @Override
  public Object getItem(int position) {
    return null;
  }
  @Override
  public long getItemId(int position) {
    return position;
  }
  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
    final ViewHolder holder;
    View view = convertView;
    if (view == null) {
    view = inflater.inflate(R.layout.item_grid_image, parent, false);
    holder = new ViewHolder();
    assert view != null;
    holder.imageView = (ImageView) view.findViewById(R.id.image);
    holder.progressBar = (ProgressBar) view.findViewById(R.id.progress);
    view.setTag(holder);
    } else {
    holder = (ViewHolder) view.getTag();
    }
    //加载 并 显示图片, 设置加载监听器 监听 开始加载 加载失败 加载完成 事件
    ImageLoader.getInstance()
        .displayImage(IMAGE_URLS[position], holder.imageView, options, new SimpleImageLoadingListener() {
      @Override
      public void onLoadingStarted(String imageUri, View view) {
        holder.progressBar.setProgress(0);
        holder.progressBar.setVisibility(View.VISIBLE);
      }
      @Override
      public void onLoadingFailed(String imageUri, View view, FailReason failReason) {
        holder.progressBar.setVisibility(View.GONE);
      }
      @Override
      public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
        holder.progressBar.setVisibility(View.GONE);
      }
        }, new ImageLoadingProgressListener() {
      @Override
      public void onProgressUpdate(String imageUri, View view, int current, int total) {
        holder.progressBar.setProgress(Math.round(100.0f * current / total));
      }
        });
    return view;
  }
  static class ViewHolder {
    ImageView imageView;
    ProgressBar progressBar;
  }
    }