首先建立一个微信消息类。

 class wxmessage  
   {  
       public string FromUserName { get; set; }  
       public string ToUserName { get; set; }  
        public string MsgType { get; set; }  
        public string EventName { get; set; }  
        public string Content { get; set; }
        public string EventKey { get; set; } 
    }

protected void Page_Load(object sender, EventArgs e)
     {
         wxmessage wx = GetWxMessage();
         string res = "";

         if (!string.IsNullOrEmpty(wx.EventName) && wx.EventName.Trim() == "subscribe")
         {//刚关注时的时间，用于欢迎词
             string content = "";
             content = "/:rose欢迎北京永杰友信科技有限公司/:rose\n直接回复“你好”";
             res = sendTextMessage(wx, content);
         }
         else
         {
             if (wx.MsgType == "text" && wx.Content == "你好")
             {
                 res = sendTextMessage(wx, "你好,欢迎使用北京永杰友信科技有限公司公共微信平台!");
             }
             else
             {
                 res = sendTextMessage(wx, "你好,未能识别消息!");
             }
         }

         Response.Write(res);
     }

 private wxmessage GetWxMessage()
     {
         wxmessage wx = new wxmessage();
         StreamReader str = new StreamReader(Request.InputStream, System.Text.Encoding.UTF8);
         XmlDocument xml = new XmlDocument();
         xml.Load(str);
         wx.ToUserName = xml.SelectSingleNode("xml").SelectSingleNode("ToUserName").InnerText;
         wx.FromUserName = xml.SelectSingleNode("xml").SelectSingleNode("FromUserName").InnerText;
         wx.MsgType = xml.SelectSingleNode("xml").SelectSingleNode("MsgType").InnerText;
         if (wx.MsgType.Trim() == "text")
         {
             wx.Content = xml.SelectSingleNode("xml").SelectSingleNode("Content").InnerText;
         }
         if (wx.MsgType.Trim() == "event")
         {
             wx.EventName = xml.SelectSingleNode("xml").SelectSingleNode("Event").InnerText;
         }

         
         return wx;
     }

微信公共服务平台开发（.Net 的实现）3-------发送文本消息