商户Native支付下单接口，微信后台系统返回链接参数code_url，
商户后台系统将code_url值生成二维码图片，用户使用微信客户端扫码后发起支付。
1.SDK与DEMO下载
https://pay.weixin.qq.com/wiki/doc/api/native.php?chapter=11_1
2.拷贝business与lib文件夹
3.将下载的证书解压后拷贝到cert文件夹下
4.修改lib文件夹下的DemoConfig文件

        public string GetAppID(){
            return "绑定支付的APPID";
        }
        public string GetMchID(){
            return "商户号";
        }
        public string GetKey(){
            return "配置密钥时输入的字符串";
        }

        public string GetSSlCertPath(){
            return "cert\\apiclient_cert.p12";
        }
        public string GetSSlCertPassword(){
            return "证书密码";
        }
        public string GetNotifyUrl(){
            return "支付回调方法";//最好是使用域名
        }

5.调用API返回支付Url

     NativePay nativePay = new NativePay();
     //生成扫码支付模式二url
     WxPayModel wxPayModel = new WxPayModel();
     wxPayModel.body = data.body;
     wxPayModel.attach = data.attach;
     wxPayModel.total_fee = data.total_fee;
     wxPayModel.goods_tag = data.goods_tag;
     wxPayModel.trade_type = "NATIVE";
     wxPayModel.product_id = data.product_id;
     wxPayModel.out_trade_no = out_trade_no;

     string url = nativePay.GetPayUrl(wxPayModel);

6.根据url生成二维码

引用 qrcode.js，使用new QRCode生成二维码图片
new QRCode(document.getElementById("qrcode"), data.url);

7.支付结果回调

    var buffer = new byte[Convert.ToInt32(Request.ContentLength)];
    Request.Body.ReadAsync(buffer, 0, buffer.Length);
    var body = Encoding.UTF8.GetString(buffer);//接收到的支付通知

    //将xml格式的结果转换为对象以返回
    WxPayData results = new WxPayData();
    results.FromXml(body);

    #region  更新订单状态
    OrderNotify orderNotify = new OrderNotify();
    orderNotify.return_code = results.GetValue("return_code").ToString();
    if (orderNotify.return_code == "SUCCESS")
    {
         orderNotify.attach = results.GetValue("attach").ToString();
         orderNotify.out_trade_no = results.GetValue("out_trade_no").ToString();
         orderNotify.total_fee = Convert.ToDouble(results.GetValue("total_fee").ToString()) * 0.01;
         orderNotify.transaction_id = results.GetValue("transaction_id").ToString();//微信订单号
    } 
    else
    {
         msg = "[return_code]返回状态不为[SUCCESS]";
    }
   #endregion

8.支付结果查询

     WxPayApi wxPayApi = new WxPayApi();
     string transaction_id = data.transaction_id;//微信订单号
     string out_trade_no = data.out_trade_no;//商户系统订单号
     resultmsg = OrderQuery.Run(transaction_id, out_trade_no);//调用订单查询业务逻辑 

微信Native下单V2版