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Codewx.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_keystring 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UnionId return 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！
微信小程序
