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ASP.NET Core 微信支付(一)【统一下单 APIV3】

首先声明,我这个是为APP支付提供的接口!!

官方参考资料

签名:https://pay.weixin.qq.com/wiki/doc/apiv3/wechatpay/wechatpay4_0.shtml

统一下单接口:https://pay.weixin.qq.com/wiki/doc/apiv3/apis/chapter3_2_1.shtml

查看证书序列号:https://wechatpay-api.gitbook.io/wechatpay-api-v3/chang-jian-wen-ti/zheng-shu-xiang-guan#ru-he-cha-kan-zheng-shu-xu-lie-hao

私钥和证书:https://wechatpay-api.gitbook.io/wechatpay-api-v3/ren-zheng/zheng-shu#sheng-ming-suo-shi-yong-de-zheng-shu

首先声明,我这个是为APP支付提供的接口!!!

  一、签名

    生成签名

        参考资料里面讲的比较详细,也有官方的文档,不过文档不全,导致我的调试程序一直出现问题,请求微信的统一下单接口总是报400错误(Bad Request)。

      签名生成参考官方代码,代码如下,里面有我标注的请求接口报400错误原因的代码

using System;
using System.IO;
using System.Net.Http;
using System.Security.Cryptography;
using System.Threading;
using System.Threading.Tasks;

namespace HttpHandlerDemo
{
    // 使用方法
    // HttpClient client = new HttpClient(new HttpHandler("{商户号}", "{商户证书序列号}"));
    // ...
    // var response = client.GetAsync("https://api.mch.weixin.qq.com/v3/certificates");
    public class HttpHandler : DelegatingHandler
    {
        private readonly string merchantId;//商户号
        private readonly string serialNo;//商户证书序列号

        public HttpHandler(string merchantId, string merchantSerialNo)
        {
            InnerHandler = new HttpClientHandler();

            this.merchantId = merchantId;
            this.serialNo = merchantSerialNo;
        }

        protected async override Task SendAsync(
            HttpRequestMessage request,
            CancellationToken cancellationToken)
        {
            var auth = await BuildAuthAsync(request);
            string value = $"WECHATPAY2-SHA256-RSA2048 {auth}";
            request.Headers.Add("Authorization", value);
            request.Headers.Add("Accept", "application/json");//如果缺少这句代码就会导致下单接口请求失败,报400错误(Bad Request)
            request.Headers.Add("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");//如果缺少这句代码就会导致下单接口请求失败,报400错误(Bad Request)

            return await base.SendAsync(request, cancellationToken);
        }

        protected async Task BuildAuthAsync(HttpRequestMessage request)
        {
            string method = request.Method.ToString();
            string body = "";
            if (method == "POST" || method == "PUT" || method == "PATCH")
            {
                var content = request.Content;
                body = await content.ReadAsStringAsync();//debug的时候在这里打个断点,看看body的值是多少,如果跟你传入的参数不一致,说明是有问题的,一定参考我的方法
            }

            string uri = request.RequestUri.PathAndQuery;
            var timestamp = DateTimeOffset.Now.ToUnixTimeSeconds();
            string nonce = Path.GetRandomFileName();

            string message = $"{method}\n{uri}\n{timestamp}\n{nonce}\n{body}\n";
            string signature = Sign(message);
            return $"mchid=\"{merchantId}\",nonce_str=\"{nonce}\",timestamp=\"{timestamp}\",serial_no=\"{serialNo}\",signature=\"{signature}\"";
        }

        protected string Sign(string message)
        {
            // NOTE: 私钥不包括私钥文件起始的-----BEGIN PRIVATE KEY-----
            //        亦不包括结尾的-----END PRIVATE KEY-----
            string privateKey = "{你的私钥}";
            byte[] keyData = Convert.FromBase64String(privateKey);
            using (CngKey cngKey = CngKey.Import(keyData, CngKeyBlobFormat.Pkcs8PrivateBlob))
            using (RSACng rsa = new RSACng(cngKey))
            {
                byte[] data = System.Text.Encoding.UTF8.GetBytes(message);
                return Convert.ToBase64String(rsa.SignData(data, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1));
            }
        }
    }
}

  二、统一下单

    使用方法

 var url = "https://api.mch.weixin.qq.com/v3/pay/transactions/app";
 var req = new GenerateOrderModelForWxPay
                {
                    appid = WxPayConst.appid,
                    mchid = WxPayConst.mchid,
                    description = "商品名称",
                    amount = new WxPayAmountModel
                    {
                        total = 1
                    },
                    out_trade_no = orderNumber,
                    notify_url = "https://xxx.com/api/WxPayCallback"
                };
HttpClient client = new HttpClient(new HttpHandler("{商户号}", "{商户证书序列号}"));
//GET 方式
var response = client.GetAsync("https://api.mch.weixin.qq.com/v3/certificates");

// POST 方式
 var bodyJson = new StringContent(req.ToJson(), Encoding.UTF8, "application/json"); //一定要这样传递参数,不然在加密签名的时候获取到的参数就是\\u0这种形式的数据了,不是传递的这样的数据了,导致加密的结果不正确
var response = await client.PostAsync(url, bodyJson);

// 读取统一下单之后的返回结果,这样读取出来的直接就是结果,或者错误原因,大家一定要这么搞啊!!!多么痛的领悟,会有具体的错误信息的。
var respStr = await response.Content.ReadAsStringAsync();//这里面就包含prepay_id了

 三、注意

  大家一定看接口规则里面的说明,我就是没有看,导致我搞了一天没有搞通,下面贴两个截图

最后一次编辑于  03-27  
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