Implementation method of using .NET to parse WeChat payment

Due to the widespread use of WeChat, a series of products developed based on WeChat have also emerged. This article mainly introduces the implementation method of parsing WeChat payment (.NET version). Those who are interested can learn about it.

I made a web version of WeChat payment some time ago and encountered many problems, but they were finally solved. Now I will record the development process and instructions here to give others some reference.

1. Preparation work

First of all, you must first activate the WeChat payment function. In the past, activating WeChat payment required a deposit of 30,000, but now it is no longer required, so... Made this feature.

To develop WeChat payment, you need to make relevant settings in the official account backend and WeChat merchant backend.

1. Development directory configuration

WeChat payment needs to configure the payment authorization directory in the official account background (WeChat payment = "development configuration"). The authorized directory here needs to be an online address, that is, an address that can be accessed through the Internet. The WeChat payment system needs to be able to access your address through the Internet.

The WeChat authorization directory needs to be accurate to the second or third level directory. Example: If the link to initiate payment is http://www.hxfspace.net/weixin/WeXinPay/WeXinPayChoose then the configured directory should be http: //www.hxfspace.net/weixin/WeXinPay/ where http://www. hxfspace.net is the domain name and weixin is the virtual directory WeXinPay, which is the Controller. The related payment requests are all in action in WeXinPay.

This 2, OAUTH2.0 Webpage Authorized Domaining Domaining

WeChat Payment will Make a callback to the payment request to obtain the authorization code (code), so you need to set the authorization domain name here. Of course, the domain name here must be the same as the domain name in the payment authorization directory. Don’t forget to set this up. I just forgot to set it up and spent a long time looking for the reason, crying to death.

3. Relevant parameter preparation

#To call WeChat payment, you need to initiate a payment request to the WeChat payment system through a script. For parameter description, seeWeChat official website payment platform
https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=7_7&index=6

The generation of package and paySign requires the developer key AppSecret (application key), WeChat merchant account, and WeChat payment key

2. Development process

Without further ado, let’s talk about the process after sorting out:

1. Obtain the authorization code through WeChat authorization callback

2. Obtain the authorization code through the authorization code Exchange web page authorization access_token and openid

3. Call the unified ordering interface to obtain the prepayId

4. Set up jsapi WeChat payment request parameters and initiate payment

5. Receive WeChat payment callback for subsequent operations

3. Specific development (code above)

WeChat payment can only It is very inconvenient to debug in an online environment, so it is best to record logs at every key location when you first start developing.

1. Obtain the authorization code through WeChat authorization callback

First pass the initiating payment address and related parameters to the WeChat payment interface. After the WeChat payment is successfully received and verified, it will Request your payment address and bring the authorization code.

For example, here

 //判断是否网页授权，获取授权code,没有代表没有授权，构造网页授权获取code,并重新请求
      if (string.IsNullOrEmpty(Request.QueryString["code"]))
      {
        string redirectUrl = _weChatPaySerivce.GetAuthorizeUrl(account.AppId, account.RedquestUrl,
          "STATE" + "#wechat_redirect", "snsapi_base");
        return Redirect(redirectUrl);
      }

Stitching WeChat webpage authorization Url method

public string GetAuthorizeUrl(string appId, string redirectUrl, string state, string scope)
    {
      string url = string.Format("https://open.weixin.qq.com/connect/oauth2/authorize?appid={0}&redirect_uri={1}&response_type=code&scope={2}&state={3}",
          appId, HttpUtility.UrlEncode(redirectUrl), scope, state);
      /* 这一步发送之后，客户会得到授权页面，无论同意或拒绝，都会返回redirectUrl页面。
       * 如果用户同意授权，页面将跳转至 redirect_uri/?code=CODE&state=STATE。这里的code用于换取access_token（和通用接口的access_token不通用）
       * 若用户禁止授权，则重定向后不会带上code参数，仅会带上state参数redirect_uri?state=STATE
       */
      AppLog.Write("获取到授权url:", AppLog.LogMessageType.Debug); 
      return url;
    }

2. Exchange the authorization code for web page authorization access_token and openid

After obtaining the authorization code from the first step, combine the web page authorization Request url to obtain access_token and openid

 public Tuple<string, string> GetOpenidAndAccessTokenFromCode(string appId, string code, string appSecret)
    {
      Tuple<string, string> tuple = null;
      try
      {
        string url = string.Format("https://api.weixin.qq.com/sns/oauth2/access_token?appid={0}&secret={1}&code={2}&grant_type=authorization_code", appId, appSecret, code);
        string result = WeChatPayHelper.Get(url);
        AppLog.Write("微信支付-获取openid和access_token 请求Url:" + url + "result:" + result, AppLog.LogMessageType.Debug);
        if (!string.IsNullOrEmpty(result))
        {
          var jd=Newtonsoft.Json.JsonConvert.DeserializeObject<Dictionary<string, string>>(result);
          tuple = new Tuple<string, string>(jd["openid"],jd["access_token"]);
          AppLog.Write("微信支付-获取openid和access_token成功", AppLog.LogMessageType.Debug);
        }
      }
      catch (Exception ex)
      {
        AppLog.Write("微信支付：获取openid和access_tokenu异常", AppLog.LogMessageType.Debug,ex);
      }
      return tuple;
    }

3. Call the unified ordering interface to obtain prepaymentId

The RequestHandler here is a dll packaged by others online, which helps you encapsulate the generation of signatures and some verification requests. The dll can be downloaded from their official website http://weixin.senparc.com/

//创建支付应答对象
      RequestHandler packageReqHandler = new RequestHandler(null);
      //初始化
      packageReqHandler.Init();
      //时间戳
      string timeStamp = TenPayUtil.GetTimestamp();
      //随机字符串
      string nonceStr = TenPayUtil.GetNoncestr();
      //设置package订单参数 生成prepayId预支付Id
      packageReqHandler.SetParameter("appid", account.AppId);     //公众账号ID
      packageReqHandler.SetParameter("mch_id", account.PartnertId);     //商户号
      packageReqHandler.SetParameter("nonce_str", nonceStr);          //随机字符串
      packageReqHandler.SetParameter("body", account.Body);
      packageReqHandler.SetParameter("out_trade_no", account.OrderSerialId);    //商家订单号
      packageReqHandler.SetParameter("total_fee", account.TotalAmount);          //商品金额,以分为单位(money * 100).ToString()
      packageReqHandler.SetParameter("spbill_create_ip", account.RequestIp);  //用户的公网ip，不是商户服务器IP
      packageReqHandler.SetParameter("notify_url", account.NotifyUrl);      //接收财付通通知的URL
      packageReqHandler.SetParameter("trade_type", "JSAPI");            //交易类型
      packageReqHandler.SetParameter("openid", account.OpenId);            //用户的openId
      string sign = packageReqHandler.CreateMd5Sign("key", account.PaySignKey);
      packageReqHandler.SetParameter("sign", sign);            //签名
      string prepayId = string.Empty;
      try
      {
        string data = packageReqHandler.ParseXML();
        var result = TenPayV3.Unifiedorder(data);
        MailHelp.SendMail("调用统一下单接口，下单结果：--"+result+"请求参数："+data);
        var res = XDocument.Parse(result);
        prepayId = res.Element("xml").Element("prepay_id").Value;
        AppLog.Write("调用统一下单接口获取预支付prepayId成功", AppLog.LogMessageType.Debug);
      }
      catch (Exception ex)
      {
        AppLog.Write("获取到openid和access_tokenu异常", AppLog.LogMessageType.Debug, ex);
        MailHelp.SendMail("调用统一下单接口获取预支付prepayid异常：", ex);
        return null;
      }

4. Set up jsapi WeChat Payment request parameters, initiate payment

###

我这里是首先组装好微信支付所需要的参数，然后再创建调用js脚本    

//生成JsAPI支付参数
      RequestHandler paySignReqHandler = new RequestHandler(null);
      paySignReqHandler.SetParameter("appId", account.AppId);
      paySignReqHandler.SetParameter("timeStamp", timeStamp);
      paySignReqHandler.SetParameter("nonceStr", nonceStr);
      paySignReqHandler.SetParameter("package", string.Format("prepay_id={0}", prepayId));
      paySignReqHandler.SetParameter("signType", "MD5");
      string paySign = paySignReqHandler.CreateMd5Sign("key", account.PaySignKey);
      WeChatJsPayRequestModel resultModel = new WeChatJsPayRequestModel
      {
        AppId = account.AppId,
        NonceStr = nonceStr,
        TimeStamp = timeStamp,
        Package = string.Format("prepay_id={0}", prepayId),
        PaySign = paySign,
        SignType = "MD5"
      };

创建调用脚本

private string CreateWeixinJs(WeChatJsPayRequestModel model)
    {
      string js = @"<script type=&#39;text/javascript&#39;>
                callpay();
                function jsApiCall(){
                 WeixinJSBridge.invoke(
                  &#39;getBrandWCPayRequest&#39;, {
                    requestParam
                  },
                  function (res) {
                    if(res.err_msg == &#39;get_brand_wcpay_request:ok&#39; ){
                        window.location.href = &#39;successUrl&#39;;
                    }else{
                        window.location.href = &#39;failUrl&#39;;
                    }
                  }
                 ); 
                }
               function callpay()
                {
                  if (typeof WeixinJSBridge == &#39;undefined&#39;){
                    if( document.addEventListener ){
                      document.addEventListener(&#39;WeixinJSBridgeReady&#39;, jsApiCall, false);
                    }else if (document.attachEvent){
                      document.attachEvent(&#39;WeixinJSBridgeReady&#39;, jsApiCall); 
                      document.attachEvent(&#39;onWeixinJSBridgeReady&#39;, jsApiCall);
                    }
                  }else{
                    jsApiCall();
                  }
                }
            </script>";
      string requestParam = string.Format(@"&#39;appId&#39;: &#39;{0}&#39;,&#39;timeStamp&#39;: &#39;{1}&#39;,&#39;nonceStr&#39;: &#39;{2}&#39;,&#39;package&#39;: &#39;{3}&#39;,&#39;signType&#39;: &#39;{4}&#39;,&#39;paySign&#39;: &#39;{5}&#39;",
        model.AppId, model.TimeStamp, model.NonceStr, model.Package, model.SignType, model.PaySign);
      js = js.Replace("requestParam", requestParam)
        .Replace("successUrl", model.JumpUrl + "&result=1")
        .Replace("failUrl", model.JumpUrl + "&result=0");
      AppLog.Write("生成可执行脚本成功", AppLog.LogMessageType.Debug);
      return js;
    }

 5、接收微信支付回调进行后续操作

回调的时候首先需要验证签名是否正确，保证安全性，签名验证通过之后再进行后续的操作，订单状态、通知啥的。 

ResponseHandler resHandler = new ResponseHandler(System.Web.HttpContext.Current);
      bool isSuccess = _weChatPaySerivce.ProcessNotify(resHandler);
      if (isSuccess)
      {
        string result = @"<xml>
                  <return_code><![CDATA[SUCCESS]]></return_code>
                  <return_msg><![CDATA[支付成功]]></return_msg>
                 </xml>";
        HttpContext.Response.Write(result);
        HttpContext.Response.End();
      }
      return new EmptyResult();

这里有一点需要注意，就是微信支付回调的时候微信会通知八次，好像是这个数吧，所以你需要在第一次收到通知之后，把收到请求这个状态以xml的格式响应给微信支付接口。当然你不进行这个操作也是可以的，再回调的时候 每次去判断该订单是否已经回调成功，回调成功则不进行处理就可以了。

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