The message types in WeChat are: text, picture, voice, video, geographical location, link and event message. Except for event messages, the others are collectively called ordinary messages. The push and response of messages in WeChat are transmitted in xml data packets. When a user sends a message to an official account, if the WeChat server does not receive a response within five seconds, it will disconnect and re-initiate the request, retrying a total of three times. Ordinary messages can be deduplicated using msgid to avoid the impact of duplicate messages on business logic.

If the server cannot guarantee to process and reply within five seconds, you can directly reply with an empty string. The WeChat server will not process this request and will not initiate a retry. It should be noted that the reply to the empty string mentioned here is not to reply to an empty text message, but to respond directly to Response.Write("").

The following is a brief explanation of each common message.

Text message:

<xml>
 <ToUserName><![CDATA[toUser]]></ToUserName>
 <FromUserName><![CDATA[fromUser]]></FromUserName> 
 <CreateTime>1348831860</CreateTime>
 <MsgType><![CDATA[text]]></MsgType>
 <Content><![CDATA[this is a test]]></Content>
 <MsgId>1234567890123456</MsgId>
 </xml>

Picture message:

<xml>
 <ToUserName><![CDATA[toUser]]></ToUserName>
 <FromUserName><![CDATA[fromUser]]></FromUserName>
 <CreateTime>1348831860</CreateTime>
 <MsgType><![CDATA[image]]></MsgType>
 <PicUrl><![CDATA[this is a url]]></PicUrl>
 <MediaId><![CDATA[media_id]]></MediaId>
 <MsgId>1234567890123456</MsgId>
 </xml>

Voice message:

<xml><ToUserName><![CDATA[toUser]]></ToUserName><FromUserName><![CDATA[fromUser]]></FromUserName><CreateTime>1357290913</CreateTime><MsgType><![CDATA[voice]]></MsgType><MediaId><![CDATA[media_id]]></MediaId><Format><![CDATA[Format]]></Format><MsgId>1234567890123456</MsgId></xml>

Video message:

<xml><ToUserName><![CDATA[toUser]]></ToUserName><FromUserName><![CDATA[fromUser]]></FromUserName><CreateTime>1357290913</CreateTime><MsgType><![CDATA[video]]></MsgType><MediaId><![CDATA[media_id]]></MediaId><ThumbMediaId><![CDATA[thumb_media_id]]></ThumbMediaId><MsgId>1234567890123456</MsgId></xml>

Geolocation message:

<xml><ToUserName><![CDATA[toUser]]></ToUserName><FromUserName><![CDATA[fromUser]]></FromUserName><CreateTime>1351776360</CreateTime><MsgType><![CDATA[location]]></MsgType><Location_X>23.134521</Location_X><Location_Y>113.358803</Location_Y><Scale>20</Scale><Label><![CDATA[位置信息]]></Label><MsgId>1234567890123456</MsgId></xml>

Link message:

<xml><ToUserName><![CDATA[toUser]]></ToUserName><FromUserName><![CDATA[fromUser]]></FromUserName><CreateTime>1351776360</CreateTime><MsgType><![CDATA[link]]></MsgType><Title><![CDATA[公眾平臺官網(wǎng)鏈接]]></Title><Description><![CDATA[公眾平臺官網(wǎng)鏈接]]></Description><Url><![CDATA[url]]></Url><MsgId>1234567890123456</MsgId></xml>

Careful programmers should have discovered that all messages (including event messages) contain the following fields

Parameter	Description
ToUserName	Receiver’s WeChat ID
FromUserName	Sender’s WeChat ID, if it is normal The user is an OpenID
CreateTime	Message creation time
MsgType	Message type

The types of messages have been mentioned at the beginning of the article, they are: text, image, voice, video, geographical location (location), link (link), event (event)

In order to facilitate management and code writing, we can write an enumeration for these message types. As follows:

/// <summary>
    /// 消息類型枚舉    /// </summary>
    public enum MsgType
    {        /// <summary>
        ///文本類型        /// </summary>        TEXT,        /// <summary>
        /// 圖片類型        /// </summary>        IMAGE,        /// <summary>
        /// 語音類型        /// </summary>        VOICE,        /// <summary>
        /// 視頻類型        /// </summary>        VIDEO,        /// <summary>
        /// 地理位置類型        /// </summary>        LOCATION,        /// <summary>
        /// 鏈接類型        /// </summary>        LINK,        /// <summary>
        /// 事件類型        /// </summary>        EVENT
    }

Let me explain here, event is a keyword in C#, so event cannot be used in enumerations, so for the sake of uniformity, I use all uppercase for enumerations here.

Since all message bodies have the above fields, you can write a base class, and then different message entities inherit this base class. (I have been struggling with a problem. I used to write all the fields in the message body in a class, which is very convenient to call. However, there are more and more fields in the class, which makes me uncomfortable. In addition, I I have little knowledge and object-oriented and am not proficient in using it, so I always list all the fields in a class

When calling, directly var ss = WeiXinRequest.RequestHelper(token, EncodingAESKey, appid ; The readability has been improved, but calling it is not as convenient as before. Friends, please give me some suggestions

)

The following are the base classes of each message entity:

public abstract class BaseMessage
    {        /// <summary>
        /// 開發(fā)者微信號        /// </summary>
        public string ToUserName { get; set; }       /// <summary>
        /// 發(fā)送方帳號（一個OpenID）       /// </summary>
        public string FromUserName { get; set; }        /// <summary>
        /// 消息創(chuàng)建時間 （整型）        /// </summary>
        public string CreateTime { get; set; }        /// <summary>
        /// 消息類型        /// </summary>
        public MsgType MsgType { get; set; }        public virtual void ResponseNull()
        {
            Utils.ResponseWrite("");
        }        public virtual void ResText(EnterParam param, string content)
        {            
        }        /// <summary>
        /// 回復(fù)消息(音樂)        /// </summary>
        public  void ResMusic(EnterParam param, Music mu)
        {
        }        public  void ResVideo(EnterParam param, Video v)
        {        }        /// <summary>
        /// 回復(fù)消息(圖片)        /// </summary>
        public  void ResPicture(EnterParam param, Picture pic, string domain)
        {
}        /// <summary>
        /// 回復(fù)消息（圖文列表）        /// </summary>
        /// <param name="param"></param>
        /// <param name="art"></param>
        public  void ResArticles(EnterParam param, List<Articles> art)
        {        }        /// <summary>
        /// 多客服轉(zhuǎn)發(fā)        /// </summary>
        /// <param name="param"></param>
        public  void ResDKF(EnterParam param)
        {
}        /// <summary>
        /// 多客服轉(zhuǎn)發(fā)如果指定的客服沒有接入能力(不在線、沒有開啟自動接入或者自動接入已滿)，該用戶會一直等待指定客服有接入能力后才會被接入，而不會被其他客服接待。建議在指定客服時，先查詢客服的接入能力指定到有能力接入的客服，保證客戶能夠及時得到服務(wù)。        /// </summary>
        /// <param name="param">用戶發(fā)送的消息體</param>
        /// <param name="KfAccount">多客服賬號</param>
        public  void ResDKF(EnterParam param, string KfAccount)
        {        }        private  void Response(EnterParam param, string data)
        {            
        }
    }

The base class defines the public fields of the message body and the virtual methods used to respond to user requests (the response message is not the focus of this article, so the method body is not posted. Please pay attention to subsequent articles) .

One of the parameters of the method in the base class is of type EnterParam. This class is the parameter that needs to be used when the user accesses and verifies the authenticity of the message, including token, encryption key, appid, etc. The definition is as follows:

/// <summary>
    /// 微信接入?yún)?shù)    /// </summary>
    public class EnterParam
    {        /// <summary>
        /// 是否加密        /// </summary>
        public bool IsAes { get; set; }        /// <summary>
        /// 接入token        /// </summary>
        public string token { get; set; }        /// <summary>
        ///微信appid        /// </summary>
        public string appid { get; set; }        /// <summary>
        /// 加密密鑰        /// </summary>
        public string EncodingAESKey { get; set; }
    }

Text entity:

public class TextMessage:BaseMessage
    {       /// <summary>
       /// 消息內(nèi)容       /// </summary>
        public string Content { get; set; }       /// <summary>
        /// 消息id，64位整型       /// </summary>
        public string MsgId { get; set; }

    
    }

Picture entity:

public class ImgMessage : BaseMessage
    {       /// <summary>
       /// 圖片路徑       /// </summary>
        public string PicUrl { get; set; }       /// <summary>
        /// 消息id，64位整型       /// </summary>
        public string MsgId { get; set; }        /// <summary>
        /// 媒體ID        /// </summary>
        public string MediaId { get; set; }

     
    }

Voice entity:

public class VoiceMessage : BaseMessage
    {       /// <summary>
       /// 縮略圖ID       /// </summary>
        public string MsgId { get; set; }       /// <summary>
        /// 格式       /// </summary>
        public string Format { get; set; }        /// <summary>
        /// 媒體ID        /// </summary>
        public string MediaId { get; set; }        /// <summary>
        /// 語音識別結(jié)果        /// </summary>
        public string Recognition { get; set; }

    
    }

Video entity:

public class VideoMessage : BaseMessage
    {       /// <summary>
       /// 縮略圖ID       /// </summary>
        public string ThumbMediaId { get; set; }       /// <summary>
        /// 消息id，64位整型       /// </summary>
        public string MsgId { get; set; }        /// <summary>
        /// 媒體ID        /// </summary>
        public string MediaId { get; set; }

    
    }

Link entity:

public class LinkMessage : BaseMessage
    {       /// <summary>
       /// 縮略圖ID       /// </summary>
        public string MsgId { get; set; }       /// <summary>
        /// 標題       /// </summary>
        public string Title { get; set; }        /// <summary>
        /// 描述        /// </summary>
        public string Description { get; set; }        /// <summary>
        /// 鏈接地址        /// </summary>
        public string Url { get; set; }

     
    }

After the message entity is defined, the next step is to parse the message body pushed by the WeChat server into the corresponding entity. I originally planned to use the XML serialization that comes with C# to send serialized components, but when I tried it, I always reported some XMLs error, so I simply used reflection to write a processing method:

public static T ConvertObj<T>(string xmlstr)
        {
            XElement xdoc = XElement.Parse(xmlstr);            var type = typeof(T);            var t = Activator.CreateInstance<T>();            foreach (XElement element in xdoc.Elements())
            {                var pr = type.GetProperty(element.Name.ToString());                if (element.HasElements)
                {//這里主要是兼容微信新添加的菜單類型。nnd，竟然有子屬性，所以這里就做了個子屬性的處理                    foreach (var ele in element.Elements())
                    {
                        pr = type.GetProperty(ele.Name.ToString());
                        pr.SetValue(t, Convert.ChangeType(ele.Value, pr.PropertyType), null);
                    }                    continue;
                }                if (pr.PropertyType.Name == "MsgType")//獲取消息模型
                {
                    pr.SetValue(t, (MsgType)Enum.Parse(typeof(MsgType), element.Value.ToUpper()), null);                    continue;
                }                if (pr.PropertyType.Name == "Event")//獲取事件類型。
                {
                    pr.SetValue(t, (Event)Enum.Parse(typeof(Event), element.Value.ToUpper()), null);                    continue;
                }
                pr.SetValue(t, Convert.ChangeType(element.Value, pr.PropertyType), null);
            }            return t;
        }

The method for processing XML is well defined. Finally, the following is about parsing the corresponding entities according to different message types:

public class MessageFactory
    {        public static BaseMessage CreateMessage(string xml)
        {
            XElement xdoc = XElement.Parse(xml);            var msgtype = xdoc.Element("MsgType").Value.ToUpper();
            MsgType type = (MsgType)Enum.Parse(typeof(MsgType), msgtype);            switch (type)
            {                case MsgType.TEXT: return Utils.ConvertObj<TextMessage>(xml);                case MsgType.IMAGE: return Utils.ConvertObj<ImgMessage>(xml);                case MsgType.VIDEO: return Utils.ConvertObj<VideoMessage>(xml);                case MsgType.VOICE: return Utils.ConvertObj<VoiceMessage>(xml);                case MsgType.LINK:                    return Utils.ConvertObj<LinkMessage>(xml);                case MsgType.LOCATION:                    return Utils.ConvertObj<LocationMessage>(xml);                case MsgType.EVENT://事件類型                {
                    
                } break;                default:                    return Utils.ConvertObj<BaseMessage>(xml);
            }
        }
    }

CreateMessage method passes in the data packet (if encrypted, it needs to be decrypted and passed in), and returns the corresponding entity in the form of a base class .

The reception of ordinary messages is almost finished here. Combined with the previous blog post, now the modified access code is posted as follows:

public class WxRequest
    {       public static BaseMessage Load(EnterParam param, bool bug = true)
       {           string postStr = "";
           Stream s = VqiRequest.GetInputStream();//此方法是對System.Web.HttpContext.Current.Request.InputStream的封裝，可直接代碼
           byte[] b = new byte[s.Length];
           s.Read(b, 0, (int)s.Length);
           postStr = Encoding.UTF8.GetString(b);//獲取微信服務(wù)器推送過來的字符串
           var timestamp = VqiRequest.GetQueryString("timestamp");           var nonce = VqiRequest.GetQueryString("nonce");           var msg_signature = VqiRequest.GetQueryString("msg_signature");           var encrypt_type = VqiRequest.GetQueryString("encrypt_type");           string data = "";           if (encrypt_type=="aes")//加密模式處理           {
               param.IsAes = true;               var ret = new MsgCrypt(param.token, param.EncodingAESKey, param.appid);               int r = ret.DecryptMsg(msg_signature, timestamp, nonce, postStr, ref data);               if (r != 0)
               {
                   WxApi.Base.WriteBug("消息解密失敗");                   return null;

               }
           }           else
           {
               param.IsAes = false;
               data = postStr;
           }           if (bug)
           {
               Utils.WriteTxt(data);
           }           return MessageFactory.CreateMessage(data);
       }
    }

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