linq to xml运用示例

代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Http;
using XFK.LYTravel.Common.helper;
using XFK.LYTravel.Infrastructure;
using SFast;
using System.Xml.Linq;
using XFK.LYTravel.Common;

namespace XFK.LYTravel.LYTravelApi.Areas.AppMain.Controllers
{
    public class WXUnifiedOrderPayController : ApiController
    {
        public ResponseBase<WXUnifiedPayResp> Post(WXUnifiedPayReq req)
        {
            AppMainLogHelper.WriteLog("-----进入AppMain-WXUnifiedOrderPay接口！（/api/AppMain/WXUnifiedOrderPay）------");
            AppMainLogHelper.WriteLog("入参：" + req._ToJsonStr());
            ResponseBase<WXUnifiedPayResp> result = new ResponseBase<WXUnifiedPayResp>();
            XElement xe = new XElement("xml",
                new XElement("appid", req.appid),
                new XElement("attach", req.attach),
                new XElement("body", req.body),
                new XElement("mch_id", req.mch_id),
                new XElement("nonce_str", req.nonce_str),
                new XElement("notify_url", req.notify_url),
                new XElement("openid", req.openid),
                new XElement("out_trade_no", req.out_trade_no),
                new XElement("spbill_create_ip", req.spbill_create_ip),
                new XElement("total_fee", req.total_fee),
                new XElement("trade_type", req.trade_type),
                new XElement("scene_info", req.scene_info),
                new XElement("sign", req.sign)
                );
            string xmlStr = xe.ToString();
            string url = "https://api.mch.weixin.qq.com/pay/unifiedorder";
            AppMainLogHelper.WriteLog(string.Format("发送微信统一下单接口，地址：{0}，参数：{1}", url, xmlStr));
            string strResp = TrainTicketAPI.PostWebRequest(url, xmlStr);
            AppMainLogHelper.WriteLog("返回数据：" + strResp);
            XElement xeRet = XElement.Parse(@strResp);
            WXUnifiedPayResp resp = new WXUnifiedPayResp();
            resp.return_code = xeRet.Descendants("return_code").First().Value;
            resp.return_msg = xeRet.Descendants("return_msg").First().Value;
            if (resp.return_code == "SUCCESS")
            {
                resp.appid = xeRet.Descendants("appid").First().Value;
                resp.mch_id = xeRet.Descendants("mch_id").First().Value;
                resp.nonce_str = xeRet.Descendants("nonce_str").First().Value;
                resp.sign = xeRet.Descendants("sign").First().Value;
                resp.result_code = xeRet.Descendants("result_code").First().Value;
                if (resp.result_code == "SUCCESS")
                {
                    resp.prepay_id = xeRet.Descendants("prepay_id").First().Value;
                    resp.trade_type = xeRet.Descendants("trade_type").First().Value;
                    resp.mweb_url = xeRet.Descendants("mweb_url").First().Value;
                }
                result.resultCode = "200";
                result.IsSuccess = true;
                result.Message = resp.return_msg;
                result.ResultData = resp;
            }
            else
            {
                result.resultCode = "201";
                result.IsSuccess = false;
                result.Message = resp.return_msg;
                result.ResultData = null;
            }

            return result;
        }

    }

    public class WXUnifiedPayReq
    {
        public string appid { get; set; }
        public string attach { get; set; }
        public string body { get; set; }
        public string mch_id { get; set; }
        public string nonce_str { get; set; }
        public string notify_url { get; set; }
        public string openid { get; set; }
        public string out_trade_no { get; set; }
        public string spbill_create_ip { get; set; }
        public string total_fee { get; set; }
        public string trade_type { get; set; }
        public string scene_info { get; set; }
        public string sign { get; set; }
    }

    public class WXUnifiedPayResp
    {
        public string return_code { get; set; }
        public string return_msg { get; set; }
        public string appid { get; set; }
        public string mch_id { get; set; }
        public string nonce_str { get; set; }
        public string sign { get; set; }
        public string result_code { get; set; }
        public string prepay_id { get; set; }
        public string trade_type { get; set; }
        public string mweb_url { get; set; }
    }
}

参考：
http://skybirdzw.blog.163.com/blog/static/7257062620140244456725/
http://skybirdzw.blog.163.com/blog/static/72570626201402445651865/