微信小程序与卡券功能小结

前段时间公司有一个微信小程序的项目，其中有与卡券打通的功能，但是微信的官方文档实在是一言难尽。。。找了很多资料才解决这个问题，其中涉及到卡券的领取，卡券的核销等，在这里做一个小结方便使用。

一、需求描述

用户可以在小程序内查看卡券，核销卡券。

二、功能实现

微信的卡券事件是发生在公众号里的，由公众号发出卡券，用户领取时微信会推送事件给开发者，开发者可以通过该事件获取到用户的信息和卡券的信息。这一步可以将用户领取过的所有卡券记录下来，方便之后和用户一一对应，以便在小程序中找到用户拥有什么卡券。

1.卡券的领取事件推送

//可以将获得的参数写入数据库以便后续操作
string eventType = rootElement.SelectSingleNode("Event") == null ? "" : rootElement.SelectSingleNode("Event").InnerText;
if (eventType == "user_get_card") {HttpContext.Current.Response.Write("");string FromUserName = rootElement.SelectSingleNode("FromUserName");string CardId = rootElement.SelectSingleNode("CardId");string IsGiveByFriend = rootElement.SelectSingleNode("IsGiveByFriend");string UserCardCode = rootElement.SelectSingleNode("UserCardCode");string FriendUserName = rootElement.SelectSingleNode("FriendUserName");string OuterId = rootElement.SelectSingleNode("OuterId");string OldUserCardCode = rootElement.SelectSingleNode("OldUserCardCode");string OuterStr = rootElement.SelectSingleNode("OuterStr");string IsRestoreMemberCard = rootElement.SelectSingleNode("IsRestoreMemberCard");string IsRecommendByFriend = rootElement.SelectSingleNode("IsRecommendByFriend");string UnionId = rootElement.SelectSingleNode("UnionId");
}

2.卡券的删除事件推送

if (eventType == "user_del_card") {HttpContext.Current.Response.Write("");string FromUserName = rootElement.SelectSingleNode("FromUserName");string CardId = rootElement.SelectSingleNode("CardId");string UserCardCode = rootElement.SelectSingleNode("UserCardCode");
}

3.卡券的核销事件推送

if (eventType == "user_consume_card") {HttpContext.Current.Response.Write("");string FromUserName = rootElement.SelectSingleNode("FromUserName");string CardId = rootElement.SelectSingleNode("CardId");string UserCardCode = rootElement.SelectSingleNode("UserCardCode");string ConsumeSource = rootElement.SelectSingleNode("ConsumeSource");
}

之所以先把卡券推送事件写出来的原因是：微信公众号与微信小程序之间是靠 UnionId 来关联的，在绑定了同一个开放平台（微信开放平台）下的公众号和小程序，每一个用户都有一个独立的UnionId，这个UnionId在这些公众号和小程序下是相同的，因此可以通过UnionId来匹配到用户在公众号内领取到的卡券。

4.在小程序内查看用户的卡券

在得到卡券信息后，我们就可以通过小程序内用户授权拿到的UnionId，来判断用户有什么卡券了。
第一步需要先获取到用户的UnionId。

//1.先调用wx.login获取到登录的Code
wx.login({success: function (res) {let code = res.code;}
})//2.把这个Code作为参数，去获取登录态的Session_key
string code = "******";
string appid = "******";
string appsecret = "******";
Stream instream = null;
StreamReader sr = null;
HttpWebResponse response = null;
HttpWebRequest request = null;
Encoding encoding = Encoding.UTF8;
try {string url = string.Format("https://api.weixin.qq.com/sns/jscode2session?appid={0}&secret={1}&js_code={2}&grant_type=authorization_code", appid, appsecret, code);request = WebRequest.Create(url) as HttpWebRequest;CookieContainer cookieContainer = new CookieContainer();request.CookieContainer = cookieContainer;request.AllowAutoRedirect = true;request.Method = "GET";request.ContentType = "application/x-www-form-urlencoded";//发送请求并获取相应回应数据response = request.GetResponse() as HttpWebResponse;//直到request.GetResponse()程序才开始向目标网页发送Post请求instream = response.GetResponseStream();sr = new StreamReader(instream, encoding);//返回结果网页（html）代码string content = sr.ReadToEnd();return content;
} catch (Exception ex) {return ex;
}//接着将返回的SessionKey和通过wx.getUserInfo接口获得的加密信息encryptedData和iv，通过解密得到UnionId。
string session_key = "******";
string encryptedData = "******";
string iv = "******";
try {byte[] iv2 = Convert.FromBase64String(iv);if (string.IsNullOrEmpty(encryptedData)) return“ 解密失败”;Byte[] toEncryptArray = Convert.FromBase64String(encryptedData);System.Security.Cryptography.RijndaelManaged rm = new System.Security.Cryptography.RijndaelManaged {Key = Convert.FromBase64String(session_key),IV = iv2,Mode = System.Security.Cryptography.CipherMode.CBC,Padding = System.Security.Cryptography.PaddingMode.PKCS7};System.Security.Cryptography.ICryptoTransform cTransform = rm.CreateDecryptor();Byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);string ra = Encoding.UTF8.GetString(resultArray); //解密成功字符串，其中包括UnionIdreturn ra;
} catch (Exception ex) {return ex;
}

在我们获取到UnionId之后，就已经完成了在小程序内查看卡包的功能。由于在之前的卡券推送事件中获取又到了卡券的Code和用户的unionid，又在小程序里得到了用户的unionid，在绑定同一开放平台的情况下，我们不难得出用户拥有哪些卡券，再调用核销接口，就可以核销掉用户的卡券了。

由于某些卡券是有条件的，所以我们可以调用接口查看卡券的详细信息进行筛选。

string cardid = "******";
string code = "******";
try {string access_token = GetAccessToken();string url = string.Format("https://api.weixin.qq.com/card/membercard/userinfo/get?access_token={0}", access_token);string result = "";HttpWebRequest req = (HttpWebRequest) WebRequest.Create(url);req.Method = "POST";req.ContentType = "application/x-www-form-urlencoded";StringBuilder builder = new StringBuilder();int i = 0;string postData = "{\"card_id\":\"" + cardid + "\",\"code\":\"" + code + "\"}";byte[] data = Encoding.UTF8.GetBytes(postData);req.ContentLength = data.Length;using(Stream reqStream = req.GetRequestStream()) {reqStream.Write(data, 0, data.Length);reqStream.Close();}HttpWebResponse resp = (HttpWebResponse) req.GetResponse();Stream stream = resp.GetResponseStream();//获取响应内容using(StreamReader reader = new StreamReader(stream, Encoding.UTF8)) {result = reader.ReadToEnd();}return result;
} catch (Exception ex) {return ex;
}

5.核销卡券

try {string code = "******";string unionid = "******";string storeId = "******";string token = GetAccessToken();string url = string.Format("https://api.weixin.qq.com/card/code/consume?access_token={0}", token);string result = "";HttpWebRequest req = (HttpWebRequest) WebRequest.Create(url);req.Method = "POST";req.ContentType = "application/x-www-form-urlencoded";StringBuilder builder = new StringBuilder();int i = 0;string postData = "{\"code\":\"" + code + "\"}";byte[] data = Encoding.UTF8.GetBytes(postData);req.ContentLength = data.Length;using(Stream reqStream = req.GetRequestStream()) {reqStream.Write(data, 0, data.Length);reqStream.Close();}HttpWebResponse resp = (HttpWebResponse) req.GetResponse();Stream stream = resp.GetResponseStream();//获取响应内容using(StreamReader reader = new StreamReader(stream, Encoding.UTF8)) {result = reader.ReadToEnd();}return result;
} else {return false;
}
} catch (Exception ex) {return false;
}

至此，我们便完成了如何在小程序内查看并使用微信公众号领取的卡券。但是还有一种情况便是我们在小程序内领取会员卡，这里也一并写上。

//首先需要获取到会员卡的必要参数（这里用到了Senparc的DLL）string access_token = "******";string ticket = “******”; //只需要将access_token传入接口后便可获得，这里不再列出方法string nonceStr = TenPayV3Util.GetNoncestr();string timeStamp = TenPayV3Util.GetTimestamp();string card_id = "******";string signature = GetCardSignature(ticket, card_id, nonceStr, timeStamp, out signature);string jsonStr = "{\"Ticket\":\"" + ticket + "\",\"NonceStr\":\"" + nonceStr + "\",\"TimeStamp\":\"" + timeStamp + "\",\"CardId\":\"" + card_id + "\",\"Signature\":\"" + signature.ToLower() + "\"}";return jsonStr;//获取签名
public string GetCardSignature(string api_ticket, string card_id, string noncestr, string timestamp, out string string1) {List < string > ss = new List < string > () {api_ticket,timestamp,noncestr,card_id};var list = ss.OrderBy(x => x, StringComparer.Ordinal).ToArray();string1 = string.Join("", list);return SHA1(string1, Encoding.UTF8);
}//SHA1解密
public static string SHA1(string content, Encoding encode) {try {SHA1 sha1 = new SHA1CryptoServiceProvider();byte[] bytes_in = encode.GetBytes(content);byte[] bytes_out = sha1.ComputeHash(bytes_in);sha1.Dispose();string result = BitConverter.ToString(bytes_out);result = result.Replace("-", "");return result;} catch (Exception ex) {throw new Exception("SHA1加密出错：" + ex.Message);}
}//将返回的参数传入wx.addCard接口即可
wx.addCard({cardList: [{cardId: '',cardExt: '{"code": "", "openid": "", "timestamp": "", "signature":""}'}, {cardId: '',cardExt: '{"code": "", "openid": "", "timestamp": "", "signature":""}'}],success (res) {console.log(res.cardList) // 卡券添加结果}
})

总结

希望大家在完成卡券功能时都能迎刃而解~觉得有帮助的麻烦点个赞哈！