WeChat の開発 WeChat がメッセージを送信する

/// <summary>
        ///      http  get/post 公用方法
        /// </summary>
        /// <param name="requestUrl">请求链接</param>
        /// <param name="requestJsonParams">请求参数值（如果是get方式此处为“”值,默认为 ""）</param>
        /// <param name="requestMethod">请求方式  post or get</param>
        /// <returns></returns>
        public static string Request(this string requestUrl, string requestMethod, string requestJsonParams = "")
        {
            string returnText = "";
            StreamReader streamReader = null;
            HttpWebRequest request = null;
            HttpWebResponse response = null;

            Encoding encoding = Encoding.UTF8;
            request = (HttpWebRequest)WebRequest.Create(requestUrl);
            request.Method = requestMethod;
            if (!string.IsNullOrEmpty(requestJsonParams) && requestMethod.ToLower() == "post")
            {
                byte[] buffer = encoding.GetBytes(requestJsonParams);
                request.ContentLength = buffer.Length;
                request.GetRequestStream().Write(buffer, 0, buffer.Length);
            }

            try
            {
                response = (HttpWebResponse)request.GetResponse();
                using (streamReader = new StreamReader(response.GetResponseStream(), System.Text.Encoding.GetEncoding("gb2312")))//utf-8
                {
                    returnText = streamReader.ReadToEnd();
                }
            }
            catch (Exception ex)
            {
                returnText = ex.Message;
            }

            return returnText;
        }

/// <summary>
        ///     发送微信信息(单用户发送)
        /// </summary>
        /// <param name="access_token">授权码（微信token）</param>
        /// <param name="messageInfo">发送信息模型</param>
        /// <returns></returns>
        public static string SendSingleMessage(WeChatParamEntity messageInfo, string access_token)
        {
            messageInfo.MsgType = string.IsNullOrEmpty(messageInfo.MsgType) ? "text" : messageInfo.MsgType;
            string jsonDataParams = messageInfo == null ? "" : JsonConvert.SerializeObject(new
            {
                touser = messageInfo.ToUser,
                msgtype = messageInfo.MsgType,
                text = new { content = messageInfo.Text }
            });
            string requestUrl = string.Format(Consts.URL_POSTSINGLETEXTMESSAGE, access_token);
            return requestUrl.Request("POST", jsonDataParams);
        }
        /// <summary>
        ///     发送微信信息（多用户批量发送）
        /// </summary>
        /// <param name="access_token">授权码（微信token）</param>
        /// <param name="messageInfo">发送信息模型</param>
        /// <returns></returns>
        public static string SendMessages(WeChatParamsEntity messageInfo, string access_token)
        {
            messageInfo.MsgType = string.IsNullOrEmpty(messageInfo.MsgType) ? "text" : messageInfo.MsgType;
            string jsonDataParams = messageInfo == null ? "" : JsonConvert.SerializeObject(new
            {
                touser = messageInfo.ToUser,
                msgtype = messageInfo.MsgType,
                text = new { content = messageInfo.Text }
            });
            string requestUrl = string.Format(Consts.URL_POSTTEXTMESSAGES, access_token);
            return requestUrl.Request("POST", jsonDataParams);
        }