code: public static void write(HttpServletResponse response, InputStream in, String contentType, String fileName) {
  		final String charset = ObjectUtil.defaultIfNull(response.getCharacterEncoding(), CharsetUtil.UTF_8);
  		response.setHeader("Content-Disposition", StrUtil.format("attachment;filename={}", URLUtil.encode(fileName, charset)));
  		response.setContentType(contentType);
  		write(response, in);
  	}
docs: 返回数据给客户端
  
  @param response 响应对象{@link HttpServletResponse}
  @param in 需要返回客户端的内容
  @param contentType 返回的类型
  @param fileName 文件名
  @since 4.1.15