def image_url_for_name(name)
      image_url = "#{asset_host}#{ File.join(asset_path, name) }.png"
      if image_url.present?
        if asset_size.present? && asset_size.in?(sizes)
          image_url = [image_url, asset_size].join(asset_delimiter)
        end
      end
      return image_url
    end
def image_url_for_name(name)
      image_url = "#{asset_host}#{ File.join(asset_path, name) }.png"
      if image_url.present?
        if asset_size.present? && asset_size.in?(sizes)
          image_url = [image_url, asset_size].join(asset_delimiter)
        end
      end
      return image_url
    end
通过（名称）合成图片地址