public Bitmap loadImage(String url) {
    if (null == url) return null;
    Bitmap bitmap = null;
    bitmap = mImageLoader.getBitmapFromMemoryCache(url); // 从内存拿图片
    if (null != bitmap) {
      return bitmap;
    }

    // 从SD卡拿图片
    File imgFile = new File(Utils.getImagePath(url));
    if (!imgFile.exists()) {
      Utils.downloadImage(url, columnWidth); // 网络下载图片
    }

    bitmap = ImageLoader.decodeSampledBitmapFromResource(imgFile.getPath(), columnWidth - 10);
    return bitmap;
  }
 public WaterFallViews(Context context, AttributeSet attrs) {
   super(context, attrs);
   mImageLoader = ImageLoader.getInstance();
   all_container = this;
 }