紅包功能簡單介紹：

1、商戶呼叫介面時，通過指定傳送物件以及傳送金額的方式發放紅包，這樣的方式，允許商戶靈活的應用於各種各樣豐富的活動場景

2、領取到紅包後，使用者的資金直接進入微信零錢，避免繁複的領獎流程，帶給使用者微信支付原生的流暢體驗

現金紅包官網文件地址：https://pay.weixin.qq.com/wiki/doc/api/tools/cash_coupon.php?chapter=13_1

呼叫現金紅包介面需要使用到證書，請前往商戶平臺下載證書

官網有關詳細證書的介紹：https://pay.weixin.qq.com/wiki/doc/api/tools/cash_coupon.php?chapter=4_3

因為傳送現金紅包是從商戶平臺餘額扣款，所以商戶平臺的賬戶餘額必須有充足的餘額

下面是呼叫紅包介面詳細程式碼：1、簽名的MD5加密類：

         /// <summary>
         /// MD5UtilHelper 的摘要說明。
     /// </summary>
     public class MD5UtilHelper
     {
         public MD5UtilHelper()
         {
             //
             // TODO: 在此處新增建構函式邏輯
             //
         }
 
 
         /// <summary>
                 /// 獲取大寫的MD5簽名結果
         /// </summary>
         /// <param name="encypStr"></param>
         /// <param name="charset"></param>
         /// <returns></returns>
         public static string GetMD5(string encypStr, string charset)
 
         {
             string retStr;
             MD5CryptoServiceProvider m5 = new MD5CryptoServiceProvider();
 
             //建立md5物件
             byte[] inputBye;
             byte[] outputBye;
 
             //使用GB2312編碼方式把字串轉化為位元組陣列．
             try
             {
                 inputBye = Encoding.GetEncoding(charset).GetBytes(encypStr);
             }
             catch (Exception ex)
             {
                 inputBye = Encoding.GetEncoding("GB2312").GetBytes(encypStr);
             }
             outputBye = m5.ComputeHash(inputBye);
 
             retStr = System.BitConverter.ToString(outputBye);
             retStr = retStr.Replace("-", "").ToUpper();
             return retStr;
         }
     }    

2、處理引數的類：

     public class RequestHandler
     {
 
         public RequestHandler(HttpContext httpContext)
         {
             Parameters = new Hashtable();
 
             this.HttpContext = httpContext ?? HttpContext.Current;
 
         }
         /// <summary>
         /// 金鑰
         /// </summary>
         private string Key;
 
         protected HttpContext HttpContext;
 
         /// <summary>
         /// 請求的引數
         /// </summary>
         protected Hashtable Parameters;
 
         /// <summary>
         /// debug資訊
         /// </summary>
         private string DebugInfo;
 
         /// <summary>
         /// 初始化函式
         /// </summary>
         public virtual void Init()
         {
         }
         /// <summary>
         /// 獲取debug資訊
         /// </summary>
         /// <returns></returns>
         public String GetDebugInfo()
         {
             return DebugInfo;
         }
         /// <summary>
         /// 獲取金鑰
         /// </summary>
         /// <returns></returns>
         public string GetKey()
         {
             return Key;
         }
         /// <summary>
         /// 設定金鑰
         /// </summary>
         /// <param name="key"></param>
         public void SetKey(string key)
         {
             this.Key = key;
         }
 
         /// <summary>
         /// 設定引數值
         /// </summary>
         /// <param name="parameter"></param>
         /// <param name="parameterValue"></param>
         public void SetParameter(string parameter, string parameterValue)
         {
             if (parameter != null && parameter != "")
             {
                 if (Parameters.Contains(parameter))
                 {
                     Parameters.Remove(parameter);
                 }
 
                 Parameters.Add(parameter, parameterValue);
             }
         }
 
 
         /// <summary>
         /// 建立md5摘要,規則是:按引數名稱a-z排序,遇到空值的引數不參加簽名
         /// </summary>
         /// <param name="key">引數名</param>
         /// <param name="value">引數值</param>
         /// key和value通常用於填充最後一組引數
         /// <returns></returns>
         public virtual string CreateMd5Sign(string key, string value)
         {
             StringBuilder sb = new StringBuilder();
 
             ArrayList akeys = new ArrayList(Parameters.Keys);
             akeys.Sort();
 
             foreach (string k in akeys)
             {
                 string v = (string)Parameters[k];
                 if (null != v && "".CompareTo(v) != 0
                     && "sign".CompareTo(k) != 0 && "key".CompareTo(k) != 0)
                 {
                     sb.Append(k + "=" + v + "&");
                 }
             }
 
             sb.Append(key + "=" + value);
             string sign = MD5UtilHelper.GetMD5(sb.ToString(), GetCharset()).ToUpper();
 
             return sign;
         }
 
         /// <summary>
         /// 輸出XML
         /// </summary>
         /// <returns></returns>
         public string ParseXML()
         {
             StringBuilder sb = new StringBuilder();
             sb.Append("<xml>");
             foreach (string k in Parameters.Keys)
             {
                 string v = (string)Parameters[k];
                 if (Regex.IsMatch(v, @"^[0-9.]$"))
                 {
 
                     sb.Append("<" + k + ">" + v + "</" + k + ">");
                 }
                 else
                 {
                     sb.Append("<" + k + "><![CDATA[" + v + "]]></" + k + ">");
                 }
 
             }
             sb.Append("</xml>");
             return sb.ToString();
         }
 
 
 
         /// <summary>
         /// 設定debug資訊
         /// </summary>
         /// <param name="debugInfo"></param>
         public void SetDebugInfo(String debugInfo)
         {
             this.DebugInfo = debugInfo;
         }
 
         public Hashtable GetAllParameters()
         {
             return this.Parameters;
         }
 
         protected virtual string GetCharset()
         {
             return this.HttpContext.Request.ContentEncoding.BodyName;
         }
     }

3、呼叫現金紅包處理類：

      /// <summary>
     /// 企業號微信支付介面
     /// </summary>
     public static class TenPay
     {
 
         #region 企業向用戶發紅包
         /// <summary>
         /// 用於企業向微信使用者個人發紅包
         /// 目前支援向指定微信使用者的openid個人發紅包
         /// </summary>
         /// <param name="certPassword">apiclient_cert.p12證書密碼即商戶號</param>
         /// <param name="data">微信支付需要post的xml資料</param>
         /// <param name="certPath">apiclient_cert.p12的證書物理位置(例如：E:\projects\文件\微信商戶平臺證書\商戶平臺API證書</param>
         /// <param name="timeOut"></param>
         /// <returns></returns>
         public static string Sendredpack(string data, string certPassword,string certPath, int timeOut = Config.TIME_OUT)
         {
             var urlFormat = "https://api.mch.weixin.qq.com/mmpaymkttransfers/sendredpack";
             string cert = certPath;
 
             ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
             X509Certificate2 cer = new X509Certificate2(cert, certPassword, X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.MachineKeySet);
 
             var formDataBytes = data == null ? new byte[0] : Encoding.UTF8.GetBytes(data);
             MemoryStream ms = new MemoryStream();
             ms.Write(formDataBytes, 0, formDataBytes.Length);
             ms.Seek(0, SeekOrigin.Begin);//設定指標讀取位置
 
             HttpWebRequest request = (HttpWebRequest)WebRequest.Create(urlFormat);
             request.ClientCertificates.Add(cer);
             request.Method = "POST";
             request.Timeout = timeOut;
 
             request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36";
 
             #region 輸入二進位制流
             if (ms != null)
             {
                 ms.Position = 0;
                 //直接寫入流
                 Stream requestStream = request.GetRequestStream();
                 byte[] buffer = new byte[1024];
                 int bytesRead = 0;
                 while ((bytesRead = ms.Read(buffer, 0, buffer.Length)) != 0)
                 {
                     requestStream.Write(buffer, 0, bytesRead);
                 }
                 ms.Close();//關閉檔案訪問
             }
             #endregion
 
             HttpWebResponse response = (HttpWebResponse)request.GetResponse();
 
             using (Stream responseStream = response.GetResponseStream())
             {
                 using (StreamReader myStreamReader = new StreamReader(responseStream, Encoding.GetEncoding("utf-8")))
                 {
                     string retString = myStreamReader.ReadToEnd();
                     return retString;
                 }
             }
         }
         private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
         {
             if (errors == SslPolicyErrors.None)
                 return true;
             return false;
         }
         #endregion
 
     }

4、呼叫現金紅包介面

                         #region 傳送紅包
                             bool fals = false;   //記錄傳送紅包是否成功
                             string xmlResult = null;  //現金紅包介面返回的xml
                             string certPath = null;  //證書在伺服器的物理位置
                             string data = null;  //呼叫現金紅包介面需要的資料
                             try
                             {
                                 //建立支付應答物件
                                 RequestHandler packageReqHandler = new RequestHandler(null);
                                 //初始化
                                 packageReqHandler.Init();
                                 string nonceStr = TenPayV3Util.GetNoncestr();  //時間戳
                                 //設定package訂單引數
                                 packageReqHandler.SetParameter("nonce_str", nonceStr);    //隨機字串，不長於32位
                                 packageReqHandler.SetParameter("mch_billno", System.Configuration.ConfigurationManager.AppSettings["TenPayV3_MchId"] + model.JournalNumber);//商戶訂單號（每個訂單號必須唯一）組成：mch_id+yyyymmdd+10位一天內不能重複的數字。介面根據商戶訂單號支援重入，如出現超時可再呼叫。
                                 packageReqHandler.SetParameter("mch_id", System.Configuration.ConfigurationManager.AppSettings["TenPayV3_MchId"]);  //微信支付分配的商戶號
                                 packageReqHandler.SetParameter("wxappid", System.Configuration.ConfigurationManager.AppSettings["TenPayV3_AppId"]);//微信分配的公眾賬號ID（企業號corpid即為此appId）。介面傳入的所有appid應該為公眾號的appid（在mp.weixin.qq.com申請的），不能為APP的appid（在open.weixin.qq.com申請的）。 
                                 packageReqHandler.SetParameter("send_name", "測試");//商戶名稱
                                 packageReqHandler.SetParameter("re_openid", model.BankCard);  //使用者openid  接受紅包的使用者使用者在wxappid下的openid
                                 packageReqHandler.SetParameter("total_amount", Convert.ToInt32((decimal)(model.Amount * 100M)).ToString(CultureInfo.InvariantCulture));  //付款金額 單位分
                                 packageReqHandler.SetParameter("total_num", "1");  //紅包發放總人數
                                 packageReqHandler.SetParameter("wishing", "測試紅包");  //紅包祝福語
                                 packageReqHandler.SetParameter("client_ip", HttpContext.Current.Request.UserHostAddress);//Ip地址
                                 packageReqHandler.SetParameter("act_name", "測試紅包");//活動名稱
                                 packageReqHandler.SetParameter("remark", "測試紅包");     //備註
                                 string sign = packageReqHandler.CreateMd5Sign("key", System.Configuration.ConfigurationManager.AppSettings["TenPayV3_Key"]);
                                 packageReqHandler.SetParameter("sign", sign);                        //簽名
                                 data = packageReqHandler.ParseXML();
                                 certPath = Server.MapPath("~/") + System.Configuration.ConfigurationManager.AppSettings["certPath"];
                                 xmlResult = Sendredpack(data, System.Configuration.ConfigurationManager.AppSettings["TenPayV3_MchId"],certPath);
                                 var res = XDocument.Parse(xmlResult);
                                 string return_code = res.Element("xml").Element("return_code").Value;
                                 if ("SUCCESS".Equals(return_code))
                                 {
                                     string result_code = res.Element("xml").Element("result_code").Value;
                                     if ("SUCCESS".Equals(result_code))
                                     {
                                         fals = true;
                                     }
                                 }
                             }
                             catch (Exception exception)
                             {
                             }
                             #endregion

注意：證書所在資料夾許可權，IIS必須有許可權對該資料夾操作的許可權。