微信订阅号，获取用户openid

      private void Auth()
        {
            string token = ConfigurationManager.AppSettings["WeixinToken"];//从配置文件获取Token
            if (string.IsNullOrEmpty(token))
            {               
                LogTextHelper.Error(string.Format("WeixinToken 配置项没有配置！"));
            }

            string echoString = HttpContext.Current.Request.QueryString["echoStr"];
            string signature = HttpContext.Current.Request.QueryString["signature"];
            string timestamp = HttpContext.Current.Request.QueryString["timestamp"];
            string nonce = HttpContext.Current.Request.QueryString["nonce"];

            if (CheckSignature(token, signature, timestamp, nonce))
            {
                if (!string.IsNullOrEmpty(echoString))
                {
                    HttpContext.Current.Response.Write(echoString);
                    HttpContext.Current.Response.End();
                }
            }
        }

   /// <summary>
        /// 主入口
        /// </summary>
        /// <param name="msg"></param>
        private void OnRecvEvent(ReqMsgEventBase msg)
        {
            switch (msg.Event)
            {
                case Event.LOCATION:
                    break;
                case Event.subscribe:
                     string content = “openid=”+msg.FromUserName;
                    SendResponseText(msg, content);
                    break;
                case Event.unsubscribe:
                    break;
                default:
                    break;
            }

        }