/// <summary>
        /// 返回消息
        /// </summary>
        private string Return(string code, string message)
        {
            var xml = new XmlUtil();

            xml.AddCDataNode(code, WechatpayConst.ReturnCode);
            xml.AddCDataNode(message, WechatpayConst.ReturnMessage);
            return(xml.ToString());
        }
 /// <summary>
 /// 添加Xml节点
 /// </summary>
 private void AddNode(XmlUtil xml, string key, object value)
 {
     if (key.SafeString().ToLower() == WechatpayConst.TotalFee)
     {
         xml.AddNode(key, value);
         return;
     }
     xml.AddCDataNode(value, key);
 }