docs: def upload_file_from_url(self, url, file_name, dir_name=None):
          """简单上传文件(https://www.qcloud.com/document/product/436/6066)
  
          :param url: 文件url地址
          :param file_name: 文件名称
          :param dir_name: 文件夹名称（可选）
          :return:json数据串
          """
          real_file_name = str(int(time.time()*1000))
          urllib.request.urlretrieve(url, real_file_name)
          data = self.upload_file(real_file_name, file_name, dir_name)
          os.remove(real_file_name)
          return data