求代码c#模拟登录带验证码的
求案例代码或者帮忙分析啊cookie一直为空，

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Net;
using System.Drawing;
using System.Collections.Specialized;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Drawing.Imaging;
using LitJson;

/// <summary>
/// code 的摘要说明
/// </summary>
public class code
{
public code()
{
//
// TODO: 在此处添加构造函数逻辑
//
}

    public string gethf(string phone, string pwd, string code)
    {
       


        string hidden="style=1&pwdType=2&service=my&continue=/my/login/loginSuccess.do&failurl=https://zj.ac.10086.cn/login";
        string postdate ="passwd=" + pwd + "&validCode=" + code + "&billId="+phone+"&"+hidden;
        string url = "http://oa.plusbe.com/Admin/Login.aspx?action=save&username=xingch50&password=mygoogle&checkNum=" + code + "";
        string ceshi = Post(url, new NameValueCollection());
        return ceshi;
    }



    private CookieContainer cc = new CookieContainer();

    static System.Text.Encoding encoding = System.Text.Encoding.UTF8;
    private string Post(string url, NameValueCollection nvc)
    {
        StringBuilder sb = new StringBuilder();
        foreach (string key in nvc.AllKeys)
        {
            sb.Append(key + "=" + HttpUtility.UrlEncode(nvc[key]) + "&");
        }
        HttpWebRequest wc = (HttpWebRequest)HttpWebRequest.Create(url); 
 
        wc.CookieContainer = cc;
        if (!string.IsNullOrEmpty(sb.ToString()))
        {
            wc.Accept = "image/gif, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, application/x-ms-application, application/vnd.ms-xpsdocument, application/xaml+xml, application/x-ms-xbap, application/x-silverlight-2-b2, application/x-silverlight, */*";


            wc.ContentType = "application/x-www-form-urlencoded";
            wc.Referer = "http://oa.plusbe.com/Admin/Login.aspx";
            wc.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506; .NET CLR 3.5.21022)";
            wc.Headers.Add("Accept-Language", "zh-cn");
            wc.Headers.Add("UA-CPU", "x86");
            wc.AllowAutoRedirect = true;
            wc.Method = "POST";
            string postData = sb.ToString().TrimEnd('&');
            byte[] postBuffer = encoding.GetBytes(postData);
            wc.ContentLength = postBuffer.Length;
            using (Stream stream = wc.GetRequestStream())
            {
                stream.Write(postBuffer, 0, postBuffer.Length);
                stream.Flush();
                stream.Close();
            }
        }
        using (HttpWebResponse res = (HttpWebResponse)wc.GetResponse()) 
 
        {
            Stream response = res.GetResponseStream();
            if (wc.CookieContainer != null)
            {
                res.Cookies = wc.CookieContainer.GetCookies(wc.RequestUri);
            }
            string responseUrl = res.ResponseUri.ToString();
            StreamReader sr = new StreamReader(response, encoding);
            string c = sr.ReadToEnd();
            Console.WriteLine(c);
            return c;
        }
    }
    public  string GetVerifyCode(string sourceUrl, string saveVirtualAddress)//获取验证码
    {
        //CookieContainer cc = new CookieContainer();

        HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(sourceUrl);
        req.CookieContainer = cc;
        using (WebResponse res = req.GetResponse())
        {
            System.Drawing.Image bmp = Bitmap.FromStream(res.GetResponseStream());
            string fn = System.IO.Path.Combine(SysConfig.ApplicationPath + saveVirtualAddress.TrimEnd('/') + "/", Guid.NewGuid().ToString() + ".jpg");
            string address = HttpContext.Current.Server.MapPath(fn);
            bmp.Save(address, ImageFormat.Jpeg);
            return fn;
        }
    }
  

}

下面为调用代码

 code codes = new code();
        
 
        if (this.Request["action"] == "save")
        {
            string chenck = this.Request["code"];
            cath = codes.gethf("18268822438", "282157", chenck);
        }
        else
        {
            code = codes.GetVerifyCode("http://oa.plusbe.com/Admin/CodeImage.aspx", "verifycode");
        }

模拟登录 验证码 c#模拟登录
[解决办法]
aspx代码：

<tr>
                    <td class="capitalField field" align="right">
                        ：
                    </td>
                    <td class="field" colspan="2">
                        <input id="txt_CheckCode" type="text" runat="server" style="width: 146px;height:25px;" />
                        <div  style="padding-top:3px;">
                            <img src="ValidateCode.aspx?type=RM" alt="求代码c#模拟登录带验证码的,该如何解决" id="ValidateCodeImg" />
                            <a href="javascript:changeValidateCodeImg();" style="color: Blue; cursor: pointer; 
 
                                text-decoration: unerline">看不清，一</a>
                        </div>
                    </td>
                </tr>

<script language="javascript" type="text/javascript">
    function changeValidateCodeImg() {
        document.getElementById('ValidateCodeImg').src = 'ValidateCode.aspx?type=RM&temp=' + (new Date().getTime().toString(36));
    }
</script>