企業微信自建應用開發

企業微信自建應用可以讓用戶開發自己的應用並集成在企業微信裏面。我們藉助於企業微信的各種接口實現各種個性化的功能，其中一個典型的功能就是要能夠接收到用戶的輸入並根據用戶的輸入推送相關的信息給用戶，本篇博客就來實現這個功能。

準備工作：

1. 在企業微信管理後臺創建自建應用並開啓API接收功能

並且要對我們開發的Web API接口進行測試，如果通過會顯示如下的界面，否則提示“回調錯誤”

2. 接口測試工具

微信提供了在線接口測試工具，地址：https://open.work.weixin.qq.com/wwopen/devtool/interface/combine。

其中URL是我們部署到服務器的Web接口地址，Token、EncodingAESKey、ToUserName都可以從企業微信獲取到，每個企業自建應用都有獨立的AgentID，請仔細查看相關文檔。這個回調接口測試的是我們的WebAPI接口中的Get請求，如上圖所示返回狀態“成功”。如果提示“失敗”，可能我們開發的Web API接口有錯誤。

 

這裏直接提供測試通過的.NET Core 6.0（VS2022）環境下的WebAPI完整代碼供參考。

WebAPI的Controller源碼：

[ApiController]
[Route("api/[Controller]")]
public class WXController : ControllerBase
{
    [HttpGet]
    [HttpPost]
    [Route("GetMsg")]
    public string GetMsg(string msg_signature, string timestamp, string nonce, string echostr)
    {
        if (Request.Method.ToUpper().Equals("POST"))
        {
            Request.EnableBuffering();//啓動倒帶方式 
            byte[] bytes = null;
            string strHtml = string.Empty;
            using (MemoryStream ms = new MemoryStream())
            {
                Request.Body.CopyTo(ms);
                bytes = ms.ToArray();
                strHtml = Encoding.Default.GetString(bytes);
            }

            string token = "xxx"; //自行獲取
            string encodingAESKey = "xxx"; //自行獲取
            string corpId = "xxx"; //自行獲取
            string decryptEchoString = "";

            //接收
            WXBizMsgCrypt wxcpt = new WXBizMsgCrypt(token, encodingAESKey, corpId);
            int ret = wxcpt.DecryptMsg(msg_signature, timestamp, nonce, strHtml, ref decryptEchoString);

            //解析XML
            XmlDocument xml = new XmlDocument();
            xml.LoadXml(decryptEchoString);

            XmlNode toUserNameNode = xml.SelectSingleNode("/xml/ToUserName");
            XmlNode fromUserNameNode = xml.SelectSingleNode("/xml/FromUserName");
            XmlNode createTimeNode = xml.SelectSingleNode("/xml/CreateTime");
            XmlNode msgTypeNode = xml.SelectSingleNode("/xml/MsgType");
            XmlNode contentNode = xml.SelectSingleNode("/xml/Content");
            XmlNode msgIdNode = xml.SelectSingleNode("/xml/MsgId");
            XmlNode agentIDNode = xml.SelectSingleNode("/xml/AgentID");

            string toUserName = toUserNameNode.InnerText.Replace("<![CDATA[", "").Replace("]]>", "");
            string fromUserName = fromUserNameNode.InnerText.Replace("<![CDATA[", "").Replace("]]>", "");
            string createTime = createTimeNode.InnerText.Trim();
            string msgType = msgTypeNode.InnerText.Replace("<![CDATA[", "").Replace("]]>", "");
            string content = contentNode.InnerText.Replace("<![CDATA[", "").Replace("]]>", "");
            string msgId = msgIdNode.InnerText.Replace("<![CDATA[", "").Replace("]]>", "");
            string agentID = agentIDNode.InnerText.Replace("<![CDATA[", "").Replace("]]>", "");

            string msg = "你好！<a href=\"https://www.cnblogs.com/guwei4037\">點這裏查看</a>";

            dynamic item = null;
            //文字
            item = new
            {
                touser = fromUserName,
                msgtype = "text",
                agentid = "xxx",//agentid
                text = new
                {
                    content = msg
                },
                safe = "0"
            };

            var body = Newtonsoft.Json.JsonConvert.SerializeObject(item);
            var corpsecret = "xxx"; //每個企業微信自建應用都不同

            string url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=" + corpId + "&corpsecret=" + corpsecret;
            string reval = Utils.HttpUtil.GetData(url);
            dynamic temp = Newtonsoft.Json.JsonConvert.DeserializeObject<dynamic>(reval);
            string tocken = temp["access_token"];

            //獲取token,注意有效時間，可用緩存控制
            url = string.Format("https://qyapi.weixin.qq.com/cgi-bin/message/send?access_token={0}", tocken);
            string responseData = Utils.HttpUtil.PostData(url, body);
            System.Collections.IDictionary obj = Newtonsoft.Json.JsonConvert.DeserializeObject(responseData) as System.Collections.IDictionary;

            //執行保存到數據庫的操作...
            return decryptEchoString;
        }

        if (Request.Method.ToUpper().Equals("GET"))
        {
            string decryptEchoString = "";
            WXBizMsgCrypt wxcpt = new WXBizMsgCrypt("sToken", "sEncodingAESKey", "sCorpID");
            int ret = wxcpt.VerifyURL(msg_signature, timestamp, nonce, echostr, ref decryptEchoString);
            return decryptEchoString;
        }

        return "";
    }
}

裏面用到的WXBizMsgCrypt和Cryptography類的源碼，企業微信官方網站裏面都有下載。爲了方便調試我這裏也完整的貼出來。

WXBizMsgCrypt.cs：

查看代碼

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Collections;
//using System.Web;
using System.Security.Cryptography;
//-40001 ： 簽名驗證錯誤
//-40002 :  xml解析失敗
//-40003 :  sha加密生成簽名失敗
//-40004 :  AESKey 非法
//-40005 :  corpid 校驗錯誤
//-40006 :  AES 加密失敗
//-40007 ： AES 解密失敗
//-40008 ： 解密後得到的buffer非法
//-40009 :  base64加密異常
//-40010 :  base64解密異常
namespace Tencent
{
    public class WXBizMsgCrypt
    {
        string m_sToken;
        string m_sEncodingAESKey;
        string m_sCorpID;
        enum WXBizMsgCryptErrorCode
        {
            WXBizMsgCrypt_OK = 0,
            WXBizMsgCrypt_ValidateSignature_Error = -40001,
            WXBizMsgCrypt_ParseXml_Error = -40002,
            WXBizMsgCrypt_ComputeSignature_Error = -40003,
            WXBizMsgCrypt_IllegalAesKey = -40004,
            WXBizMsgCrypt_ValidateCorpid_Error = -40005,
            WXBizMsgCrypt_EncryptAES_Error = -40006,
            WXBizMsgCrypt_DecryptAES_Error = -40007,
            WXBizMsgCrypt_IllegalBuffer = -40008,
            WXBizMsgCrypt_EncodeBase64_Error = -40009,
            WXBizMsgCrypt_DecodeBase64_Error = -40010
        };

        //構造函數
	    // @param sToken: 公衆平臺上，開發者設置的Token
	    // @param sEncodingAESKey: 公衆平臺上，開發者設置的EncodingAESKey
	    // @param sCorpID: 企業號的CorpID
        public WXBizMsgCrypt(string sToken, string sEncodingAESKey, string sCorpID)
        {
            m_sToken = sToken;
            m_sCorpID = sCorpID;
            m_sEncodingAESKey = sEncodingAESKey;
        }

        //驗證URL
        // @param sMsgSignature: 簽名串，對應URL參數的msg_signature
        // @param sTimeStamp: 時間戳，對應URL參數的timestamp
        // @param sNonce: 隨機串，對應URL參數的nonce
        // @param sEchoStr: 隨機串，對應URL參數的echostr
        // @param sReplyEchoStr: 解密之後的echostr，當return返回0時有效
        // @return：成功0，失敗返回對應的錯誤碼
        public int VerifyURL(string sMsgSignature, string sTimeStamp, string sNonce, string sEchoStr, ref string sReplyEchoStr)
        {
            int ret = 0;
			if (m_sEncodingAESKey.Length!=43)
			{
				return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_IllegalAesKey;
			}
            ret = VerifySignature(m_sToken, sTimeStamp, sNonce, sEchoStr, sMsgSignature);
            if (0 != ret)
            {
                return ret;
            }
            sReplyEchoStr = "";
            string cpid = "";
            try
            {
                sReplyEchoStr = Cryptography.AES_decrypt(sEchoStr, m_sEncodingAESKey, ref cpid); //m_sCorpID);
            }
            catch (Exception)
            {
                sReplyEchoStr = "";
                return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_DecryptAES_Error;
            }
            if (cpid != m_sCorpID)
            {
                sReplyEchoStr = "";
                return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_ValidateCorpid_Error;
            }
            return 0;
        }

        // 檢驗消息的真實性，並且獲取解密後的明文
        // @param sMsgSignature: 簽名串，對應URL參數的msg_signature
        // @param sTimeStamp: 時間戳，對應URL參數的timestamp
        // @param sNonce: 隨機串，對應URL參數的nonce
        // @param sPostData: 密文，對應POST請求的數據
        // @param sMsg: 解密後的原文，當return返回0時有效
        // @return: 成功0，失敗返回對應的錯誤碼
        public int DecryptMsg(string sMsgSignature, string sTimeStamp, string sNonce, string sPostData, ref string sMsg)
        {
			if (m_sEncodingAESKey.Length!=43)
			{
				return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_IllegalAesKey;
			}
            XmlDocument doc = new XmlDocument();
            XmlNode root;
            string sEncryptMsg;
            try
            {
                doc.LoadXml(sPostData);
                root = doc.FirstChild;
                sEncryptMsg = root["Encrypt"].InnerText;
            }
            catch (Exception)
            {
                return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_ParseXml_Error;
            }
            //verify signature
            int ret = 0;
            ret = VerifySignature(m_sToken, sTimeStamp, sNonce, sEncryptMsg, sMsgSignature);
            if (ret != 0)
                return ret;
            //decrypt
            string cpid = "";
            try
            {
                sMsg = Cryptography.AES_decrypt(sEncryptMsg, m_sEncodingAESKey, ref cpid);
            }
            catch (FormatException)
            {
                sMsg = "";
                return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_DecodeBase64_Error;
            }
            catch (Exception)
            {
                sMsg = "";
                return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_DecryptAES_Error;
            }
            if (cpid != m_sCorpID)
                return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_ValidateCorpid_Error;
            return 0;
        }

        //將企業號回覆用戶的消息加密打包
        // @param sReplyMsg: 企業號待回覆用戶的消息，xml格式的字符串
        // @param sTimeStamp: 時間戳，可以自己生成，也可以用URL參數的timestamp
        // @param sNonce: 隨機串，可以自己生成，也可以用URL參數的nonce
        // @param sEncryptMsg: 加密後的可以直接回複用戶的密文，包括msg_signature, timestamp, nonce, encrypt的xml格式的字符串,
        //						當return返回0時有效
        // return：成功0，失敗返回對應的錯誤碼
        public int EncryptMsg(string sReplyMsg, string sTimeStamp, string sNonce, ref string sEncryptMsg)
        {
			if (m_sEncodingAESKey.Length!=43)
			{
				return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_IllegalAesKey;
			}
            string raw = "";
            try
            {
                raw = Cryptography.AES_encrypt(sReplyMsg, m_sEncodingAESKey, m_sCorpID);
            }
            catch (Exception)
            {
                return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_EncryptAES_Error;
            }
            string MsgSigature = "";
            int ret = 0;
            ret = GenarateSinature(m_sToken, sTimeStamp, sNonce, raw, ref MsgSigature);
            if (0 != ret)
                return ret;
            sEncryptMsg = "";

            string EncryptLabelHead = "<Encrypt><![CDATA[";
            string EncryptLabelTail = "]]></Encrypt>";
            string MsgSigLabelHead = "<MsgSignature><![CDATA[";
            string MsgSigLabelTail = "]]></MsgSignature>";
            string TimeStampLabelHead = "<TimeStamp><![CDATA[";
            string TimeStampLabelTail = "]]></TimeStamp>";
            string NonceLabelHead = "<Nonce><![CDATA[";
            string NonceLabelTail = "]]></Nonce>";
            sEncryptMsg = sEncryptMsg + "<xml>" + EncryptLabelHead + raw + EncryptLabelTail;
            sEncryptMsg = sEncryptMsg + MsgSigLabelHead + MsgSigature + MsgSigLabelTail;
            sEncryptMsg = sEncryptMsg + TimeStampLabelHead + sTimeStamp + TimeStampLabelTail;
            sEncryptMsg = sEncryptMsg + NonceLabelHead + sNonce + NonceLabelTail;
            sEncryptMsg += "</xml>";
            return 0;
        }

        public class DictionarySort : System.Collections.IComparer
        {
            public int Compare(object oLeft, object oRight)
            {
                string sLeft = oLeft as string;
                string sRight = oRight as string;
                int iLeftLength = sLeft.Length;
                int iRightLength = sRight.Length;
                int index = 0;
                while (index < iLeftLength && index < iRightLength)
                {
                    if (sLeft[index] < sRight[index])
                        return -1;
                    else if (sLeft[index] > sRight[index])
                        return 1;
                    else
                        index++;
                }
                return iLeftLength - iRightLength;

            }
        }
        //Verify Signature
        private static int VerifySignature(string sToken, string sTimeStamp, string sNonce, string sMsgEncrypt, string sSigture)
        {
            string hash = "";
            int ret = 0;
            ret = GenarateSinature(sToken, sTimeStamp, sNonce, sMsgEncrypt, ref hash);
            if (ret != 0)
                return ret;
            if (hash == sSigture)
                return 0;
            else
            {
                return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_ValidateSignature_Error;
            }
        }

        public static int GenarateSinature(string sToken, string sTimeStamp, string sNonce, string sMsgEncrypt ,ref string sMsgSignature)
        {
            ArrayList AL = new ArrayList();
            AL.Add(sToken);
            AL.Add(sTimeStamp);
            AL.Add(sNonce);
            AL.Add(sMsgEncrypt);
            AL.Sort(new DictionarySort());
            string raw = "";
            for (int i = 0; i < AL.Count; ++i)
            {
                raw += AL[i];
            }

            SHA1 sha;
            ASCIIEncoding enc;
            string hash = "";
            try
            {
                sha = new SHA1CryptoServiceProvider();
                enc = new ASCIIEncoding();
                byte[] dataToHash = enc.GetBytes(raw);
                byte[] dataHashed = sha.ComputeHash(dataToHash);
                hash = BitConverter.ToString(dataHashed).Replace("-", "");
                hash = hash.ToLower();
            }
            catch (Exception)
            {
                return (int)WXBizMsgCryptErrorCode.WXBizMsgCrypt_ComputeSignature_Error;
            }
            sMsgSignature = hash;
            return 0;
        }
    }
}

Cryptography.cs：

查看代碼

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.IO;
using System.Net;
namespace Tencent
{
    public class Cryptography
    {
        public static UInt32 HostToNetworkOrder(UInt32 inval)
        {
            UInt32 outval = 0;
            for (int i = 0; i < 4; i++)
                outval = (outval << 8) + ((inval >> (i * 8)) & 255);
            return outval;
        }

        public static Int32 HostToNetworkOrder(Int32 inval)
        {
            Int32 outval = 0;
            for (int i = 0; i < 4; i++)
                outval = (outval << 8) + ((inval >> (i * 8)) & 255);
            return outval;
        }
        /// <summary>
        /// 解密方法
        /// </summary>
        /// <param name="Input">密文</param>
        /// <param name="EncodingAESKey"></param>
        /// <returns></returns>
        /// 
        public static string AES_decrypt(String Input, string EncodingAESKey, ref string corpid)
        {
            byte[] Key;
            Key = Convert.FromBase64String(EncodingAESKey + "=");
            byte[] Iv = new byte[16];
            Array.Copy(Key, Iv, 16);
            byte[] btmpMsg = AES_decrypt(Input, Iv, Key);

            int len = BitConverter.ToInt32(btmpMsg, 16);
            len = IPAddress.NetworkToHostOrder(len);


            byte[] bMsg = new byte[len];
            byte[] bCorpid = new byte[btmpMsg.Length - 20 - len];
            Array.Copy(btmpMsg, 20, bMsg, 0, len);
            Array.Copy(btmpMsg, 20+len , bCorpid, 0, btmpMsg.Length - 20 - len);
            string oriMsg = Encoding.UTF8.GetString(bMsg);
            corpid = Encoding.UTF8.GetString(bCorpid);

            
            return oriMsg;
        }

        public static String AES_encrypt(String Input, string EncodingAESKey, string corpid)
        {
            byte[] Key;
            Key = Convert.FromBase64String(EncodingAESKey + "=");
            byte[] Iv = new byte[16];
            Array.Copy(Key, Iv, 16);
            string Randcode = CreateRandCode(16);
            byte[] bRand = Encoding.UTF8.GetBytes(Randcode);
            byte[] bCorpid = Encoding.UTF8.GetBytes(corpid);
            byte[] btmpMsg = Encoding.UTF8.GetBytes(Input);
            byte[] bMsgLen = BitConverter.GetBytes(HostToNetworkOrder(btmpMsg.Length));
            byte[] bMsg = new byte[bRand.Length + bMsgLen.Length + bCorpid.Length + btmpMsg.Length];

            Array.Copy(bRand, bMsg, bRand.Length);
            Array.Copy(bMsgLen, 0, bMsg, bRand.Length, bMsgLen.Length);
            Array.Copy(btmpMsg, 0, bMsg, bRand.Length + bMsgLen.Length, btmpMsg.Length);
            Array.Copy(bCorpid, 0, bMsg, bRand.Length + bMsgLen.Length + btmpMsg.Length, bCorpid.Length);
   
            return AES_encrypt(bMsg, Iv, Key);

        }
        private static string CreateRandCode(int codeLen)
        {
            string codeSerial = "2,3,4,5,6,7,a,c,d,e,f,h,i,j,k,m,n,p,r,s,t,A,C,D,E,F,G,H,J,K,M,N,P,Q,R,S,U,V,W,X,Y,Z";
            if (codeLen == 0)
            {
                codeLen = 16;
            }
            string[] arr = codeSerial.Split(',');
            string code = "";
            int randValue = -1;
            Random rand = new Random(unchecked((int)DateTime.Now.Ticks));
            for (int i = 0; i < codeLen; i++)
            {
                randValue = rand.Next(0, arr.Length - 1);
                code += arr[randValue];
            }
            return code;
        }

        private static String AES_encrypt(String Input, byte[] Iv, byte[] Key)
        {
            var aes = new RijndaelManaged();
            //祕鑰的大小，以位爲單位
            aes.KeySize = 256;
            //支持的塊大小
            aes.BlockSize = 128;
            //填充模式
            aes.Padding = PaddingMode.PKCS7;
            aes.Mode = CipherMode.CBC;
            aes.Key = Key;
            aes.IV = Iv;
            var encrypt = aes.CreateEncryptor(aes.Key, aes.IV);
            byte[] xBuff = null;

            using (var ms = new MemoryStream())
            {
                using (var cs = new CryptoStream(ms, encrypt, CryptoStreamMode.Write))
                {
                    byte[] xXml = Encoding.UTF8.GetBytes(Input);
                    cs.Write(xXml, 0, xXml.Length);
                }
                xBuff = ms.ToArray();
            }
            String Output = Convert.ToBase64String(xBuff);
            return Output;
        }

        private static String AES_encrypt(byte[] Input, byte[] Iv, byte[] Key)
        {
            var aes = new RijndaelManaged();
            //祕鑰的大小，以位爲單位
            aes.KeySize = 256;
            //支持的塊大小
            aes.BlockSize = 128;
            //填充模式
            //aes.Padding = PaddingMode.PKCS7;
            aes.Padding = PaddingMode.None;
            aes.Mode = CipherMode.CBC;
            aes.Key = Key;
            aes.IV = Iv;
            var encrypt = aes.CreateEncryptor(aes.Key, aes.IV);
            byte[] xBuff = null;

            #region 自己進行PKCS7補位，用系統自己帶的不行
            byte[] msg = new byte[Input.Length + 32 - Input.Length % 32];
            Array.Copy(Input, msg, Input.Length);
            byte[] pad = KCS7Encoder(Input.Length);
            Array.Copy(pad, 0, msg, Input.Length, pad.Length);
            #endregion

            #region 註釋的也是一種方法，效果一樣
            //ICryptoTransform transform = aes.CreateEncryptor();
            //byte[] xBuff = transform.TransformFinalBlock(msg, 0, msg.Length);
            #endregion

            using (var ms = new MemoryStream())
            {
                using (var cs = new CryptoStream(ms, encrypt, CryptoStreamMode.Write))
                {
                    cs.Write(msg, 0, msg.Length);
                }
                xBuff = ms.ToArray();
            }

            String Output = Convert.ToBase64String(xBuff);
            return Output;
        }

        private static byte[] KCS7Encoder(int text_length)
        {
            int block_size = 32;
            // 計算需要填充的位數
            int amount_to_pad = block_size - (text_length % block_size);
            if (amount_to_pad == 0)
            {
                amount_to_pad = block_size;
            }
            // 獲得補位所用的字符
            char pad_chr = chr(amount_to_pad);
            string tmp = "";
            for (int index = 0; index < amount_to_pad; index++)
            {
                tmp += pad_chr;
            }
            return Encoding.UTF8.GetBytes(tmp);
        }
        /**
         * 將數字轉化成ASCII碼對應的字符，用於對明文進行補碼
         * 
         * @param a 需要轉化的數字
         * @return 轉化得到的字符
         */
        static char chr(int a)
        {

            byte target = (byte)(a & 0xFF);
            return (char)target;
        }
        private static byte[] AES_decrypt(String Input, byte[] Iv, byte[] Key)
        {
            RijndaelManaged aes = new RijndaelManaged();
            aes.KeySize = 256;
            aes.BlockSize = 128;
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.None;
            aes.Key = Key;
            aes.IV = Iv;
            var decrypt = aes.CreateDecryptor(aes.Key, aes.IV);
            byte[] xBuff = null;
            using (var ms = new MemoryStream())
            {
                using (var cs = new CryptoStream(ms, decrypt, CryptoStreamMode.Write))
                {
                    byte[] xXml = Convert.FromBase64String(Input);
                    byte[] msg = new byte[xXml.Length + 32 - xXml.Length % 32];
                    Array.Copy(xXml, msg, xXml.Length);
                    cs.Write(xXml, 0, xXml.Length);
                }
                xBuff = decode2(ms.ToArray());
            }
            return xBuff;
        }
        private static byte[] decode2(byte[] decrypted)
        {
            int pad = (int)decrypted[decrypted.Length - 1];
            if (pad < 1 || pad > 32)
            {
                pad = 0;
            }
            byte[] res = new byte[decrypted.Length - pad];
            Array.Copy(decrypted, 0, res, 0, decrypted.Length - pad);
            return res;
        }
    }
}

HttpUtil.cs（我自己寫的，比較簡單，僅供參考）：

查看代碼

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Web;

namespace Utils
{
    public class HttpUtil
    {
        /// <summary>
        /// GET請求數據
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public static string GetData(string url)
        {
            string responseData = String.Empty;
            HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url);
            using (HttpWebResponse response = (HttpWebResponse)req.GetResponse())
            {
                using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
                {
                    responseData = reader.ReadToEnd();
                }
            }
            return responseData;
        }

        /// <summary>
        /// POST請求數據
        /// </summary>
        /// <param name="url"></param>
        /// <param name="type">GET or POST</param>
        /// <param name="body"></param>
        /// <returns></returns>
        public static string PostData(string url, dynamic body)
        {
            HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url);
            byte[] bs = Encoding.UTF8.GetBytes(body);
            req.Method = "POST";
            req.ContentType = "application/x-www-form-urlencoded";
            req.ContentLength = bs.Length;

            string responseData = String.Empty;

            using (Stream stream = req.GetRequestStream())
            {
                stream.Write(bs, 0, bs.Length);
            }

            using (HttpWebResponse response = (HttpWebResponse)req.GetResponse())
            {
                using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
                {
                    responseData = reader.ReadToEnd();
                }
            }

            return responseData;
        }
    }
}

除了上面的3個類，還用到Newtonsoft.Json包，可以通過Nuget獲取。

最後在Startup的ConfigureServices方法中，添加如下代碼：

查看代碼

// If using Kestrel
services.Configure<KestrelServerOptions>(options =>
{
    options.AllowSynchronousIO = true;
});

// If using IIS
services.Configure<IISServerOptions>(options =>
{
    options.AllowSynchronousIO = true;
});

否則會出現"Synchronous operations are disallowed. Call WriteAsync or set AllowSynchronousIO to true instead"的異常。

將這個Web API發佈到服務器的IIS之後，用戶可以留言給這個企業微信自建應用，自建應用收到消息後會自動推送我們定義的內容給用戶。上面的代碼演示了發送文本信息，其它類型的消息可以參考企業微信文檔完成，都是類似的代碼。

 

參考資料：

1. 接收消息文檔 https://developer.work.weixin.qq.com/document/path/90238

2. 發送消息文檔 https://developer.work.weixin.qq.com/document/path/90236