C# : HttpWebResponse 无法获取cookie的解决办法

排除浏览器等其他因素，只考虑程序的问题，
基本上是因为没在 HttpWebRequest.GetResponse 之前先对 request 的 CookieContainer 实例化

简单代码如下：

                HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(Url);
                
                myRequest.CookieContainer = new CookieContainer();

                HttpWebResponse response = (HttpWebResponse)myRequest.GetResponse();
               string _APSNET_SessionValue = response.Cookies["ASP.NET_SessionId"].Value;

如果没在 GetResponse 之前实例化 myRequest.CookieContainer,
访问 response.Cookies ， 都是空的。

//**********************************

using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Text;

using System.Text.RegularExpressions;
namespace MatchWin
{
    /// <summary> 
    ///  Http操作类 
    /// </summary> 
    public static class httptest
    {
        /// <summary> 
        ///  获取网址HTML 
        /// </summary> 
        /// <param name="URL">网址 </param> 
        /// <returns> </returns> 
        public static string GetHtml(string URL)
        {
            WebRequest wrt;
            wrt = WebRequest.Create(URL);
            wrt.Credentials = CredentialCache.DefaultCredentials;
            WebResponse wrp;
            wrp = wrt.GetResponse();
            string reader = new StreamReader(wrp.GetResponseStream(), Encoding.GetEncoding("gb2312")).ReadToEnd();
            try
            {
                wrt.GetResponse().Close();
            }
            catch (WebException ex)
            {
                throw ex;
            }
            return reader;
        }
        /// <summary> 
        /// 获取网站cookie 
        /// </summary> 
        /// <param name="URL">网址 </param> 
        /// <param name="cookie">cookie </param> 
        /// <returns> </returns> 
        public static string GetHtml(string URL, out string cookie)
        {
            WebRequest wrt;
            wrt = WebRequest.Create(URL);
            wrt.Credentials = CredentialCache.DefaultCredentials;
            WebResponse wrp;

            wrp = wrt.GetResponse();


            string html = new StreamReader(wrp.GetResponseStream(), Encoding.GetEncoding("gb2312")).ReadToEnd();

            try
            {
                wrt.GetResponse().Close();
            }
            catch (WebException ex)
            {
                throw ex;
            }

           cookie = wrp.Headers.Get("Set-Cookie");
            
            return html;
        }
        public static string GetHtml(string URL, string postData, string cookie, out string header, string server)
        {
           return GetHtml(server, URL, postData, cookie, out header);
           
        }
        public static string GetHtml(string server, string URL, string postData, string cookie, out string header)
        {
            byte[] byteRequest = Encoding.GetEncoding("gb2312").GetBytes(postData);
            return GetHtml(server, URL, byteRequest, cookie, out header);
        }

        /// <summary>
        /// C# :从一段字符串中，输入开始和结束的字符，取中间的字符
        /// </summary>
        /// <param name="str">一段字符串</param>
        /// <param name="strStart">开始字符</param>
        /// <param name="strEnd">结束字符</param>
        /// <returns></returns>
        public static string AnalyzeMessage(string str, string strStart, string strEnd)
        {
            string Result = "";
            int i = str.IndexOf(strStart);
            if (i >= 0)
            {
                int j = str.IndexOf(strEnd, i + strStart.Length);
                if (j > 0)
                {
                    Result = str.Substring(i + strStart.Length, j - i - strStart.Length);
                }
            }
            return Result;
        }

        /// <summary>
        /// 与请求相关的cookie（用于保持session）
        /// </summary>
        public static CookieContainer LoginCookies = new CookieContainer();
        public static CookieCollection gCookieCollention = new CookieCollection();
        //Cookies集合保存
        public static CookieCollection CCol = new CookieCollection();


        public static string GetHtml222(string URL,  string cookie)
        {

            HttpWebRequest httpWebRequest;
            HttpWebResponse webResponse;
       
            Stream getStream;
            StreamReader streamReader;
            string getString = "";
            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(URL);
                   
            httpWebRequest.ContentType = "application/x-www-form-urlencoded";
            httpWebRequest.Accept =
                "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";
            
            httpWebRequest.UserAgent =
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
       
            //自动跳转。。。
            httpWebRequest.AllowAutoRedirect = false;
            httpWebRequest.KeepAlive = true;
            httpWebRequest.CookieContainer = LoginCookies;

            httpWebRequest.Method = "GET";
            webResponse = (HttpWebResponse)httpWebRequest.GetResponse();

            

            getStream = webResponse.GetResponseStream();
            streamReader = new StreamReader(getStream, Encoding.GetEncoding("gb2312"));  //Encoding.GetEncoding("gb2312")    Encoding.GetEncoding("utf-8")
            getString = streamReader.ReadToEnd();

            //LoginCookies = httpWebRequest.CookieContainer;
            CCol = LoginCookies.GetCookies(httpWebRequest.RequestUri);
            //string ksfd = CCol[0].Name + CCol[0].Value;

            streamReader.Close();
            getStream.Close();



            //*********************************获取cookie
            Regex RegExFindHref = new Regex(@"<a\s+([^>]*\s*)?href\s*=\s*(?:""(?<1>[/\a-z0-9_][^""]*)""|'(?<1>[/\a-z0-9_][^']*)'
|(?<1>[/\a-z0-9_]\S*))(\s[^>]*)?>(?<2>.*?)</a>", RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.Compiled);
            string ht = "";
            for (Match m = RegExFindHref.Match(getString); m.Success; m = m.NextMatch())
            {            
                  ht = "http://agt.ibc88.com" + System.Web.HttpUtility.UrlDecode(m.Groups[1].ToString());
            }
            ht = ht.Replace("amp;", "");
            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(ht);
            ////CookieContainer co = new CookieContainer();


            httpWebRequest.CookieContainer = new CookieContainer();
            //httpWebRequest.CookieContainer.Add(new Uri(ht), "");

            httpWebRequest.ContentType = "application/x-www-form-urlencoded";
            httpWebRequest.Accept =
                "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";

            httpWebRequest.UserAgent =
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
            httpWebRequest.Method = "Get";
            //自动跳转。。。
            httpWebRequest.Referer = URL;
           httpWebRequest.AllowAutoRedirect = false;
            httpWebRequest.KeepAlive = true;
            httpWebRequest.Credentials = CredentialCache.DefaultCredentials;
            //httpWebRequest.CookieContainer = LoginCookies;

            webResponse = (HttpWebResponse)httpWebRequest.GetResponse();

            getStream = webResponse.GetResponseStream();
            streamReader = new StreamReader(getStream, Encoding.GetEncoding("gb2312"));
            getString = streamReader.ReadToEnd();

            cookie = webResponse.Headers.Get("Set-Cookie");

            streamReader.Close();
            getStream.Close();

            
            //*********************************************************************************************
            return getString;
        }

        public static string GetHtml555(string URL, string cookie)
        {
            //WebRequest wrt;
            //wrt = WebRequest.Create(URL);
            //wrt.Credentials = CredentialCache.DefaultCredentials;
            
            //WebResponse wrp;
            //wrp = wrt.GetResponse();
            //string html = new StreamReader(wrp.GetResponseStream(), Encoding.GetEncoding("gb2312")).ReadToEnd();
            //try
            //{
            //    wrt.GetResponse().Close();
            //}
            //catch (WebException ex)
            //{
            //    throw ex;
            //}
            //cookie = wrp.Headers.Get("Set-Cookie");
            //***********************************************************************

            HttpWebRequest httpWebRequest;
            HttpWebResponse webResponse;

            Stream getStream;
            StreamReader streamReader;
            string getString = "";
            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(URL);
            //CookieContainer co = new CookieContainer();
            //co.SetCookies(new Uri("https://ag.ibc88.com/"), cookie);

            

            httpWebRequest.ContentType = "application/x-www-form-urlencoded";
            httpWebRequest.Accept =
                "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";

            httpWebRequest.UserAgent =
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
            httpWebRequest.Method = "Get";
            //自动跳转。。。
            httpWebRequest.AllowAutoRedirect = false;
            httpWebRequest.KeepAlive = true;
            httpWebRequest.CookieContainer = LoginCookies;

            webResponse = (HttpWebResponse)httpWebRequest.GetResponse();

            getStream = webResponse.GetResponseStream();
            streamReader = new StreamReader(getStream, Encoding.GetEncoding("gb2312"));
            getString = streamReader.ReadToEnd();

            //cookie = webResponse.Headers.Get("Set-Cookie");

            streamReader.Close();
            getStream.Close();
            return getString;
        }


        public static string GetHtml333(string URL, string cookie, string urlReferer)
        {
            HttpWebRequest httpWebRequest;
            HttpWebResponse webResponse;

            Stream getStream;
            StreamReader streamReader;
            string getString = "";
            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(URL);

               
            httpWebRequest.ContentType = "application/x-www-form-urlencoded";
            httpWebRequest.Accept =
                "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";

            httpWebRequest.UserAgent =
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
            httpWebRequest.Method = "Get";
            //自动跳转。。。
            httpWebRequest.AllowAutoRedirect = false;
            httpWebRequest.KeepAlive = true;          

            httpWebRequest.CookieContainer = LoginCookies;          
            webResponse = (HttpWebResponse)httpWebRequest.GetResponse();           

            getStream = webResponse.GetResponseStream();
            streamReader = new StreamReader(getStream, Encoding.UTF8);
            getString = streamReader.ReadToEnd();

            streamReader.Close();
            getStream.Close();
            return getString;
        }


        public static string GetHtml(string server, string URL, byte[] byteRequest, string cookie, out string header)
        {
            
            long contentLength;
            HttpWebRequest httpWebRequest;
            HttpWebResponse webResponse;
            Stream getStream;
            StreamReader streamReader;

            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(URL);
            LoginCookies.SetCookies(new Uri(server), cookie);
            httpWebRequest.CookieContainer = LoginCookies;    
       
            httpWebRequest.ContentType = "application/x-www-form-urlencoded";
            httpWebRequest.Accept =
                "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";
            httpWebRequest.Referer = server;
            httpWebRequest.UserAgent =
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
            httpWebRequest.Method = "Post";
            httpWebRequest.AllowAutoRedirect = false;
            httpWebRequest.KeepAlive = true;
            httpWebRequest.ContentLength = byteRequest.Length;
            Stream stream;
            stream = httpWebRequest.GetRequestStream();
            stream.Write(byteRequest, 0, byteRequest.Length);
            stream.Close();
            webResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            int _APSNET_SessionValue = webResponse.Cookies.Count;
            header = webResponse.Headers.ToString();
            getStream = webResponse.GetResponseStream();
            contentLength = webResponse.ContentLength;

            byte[] outBytes = new byte[contentLength];
            outBytes = ReadFully(getStream);
            getStream.Close();

            getStream = new MemoryStream(outBytes);
            streamReader = new StreamReader(getStream, Encoding.GetEncoding("gb2312"));
            string getString = streamReader.ReadToEnd();
            streamReader.Close();
            getStream.Close();
                       

            //第二段*********************
            Regex RegExFindHref = new Regex(@"<a\s+([^>]*\s*)?href\s*=\s*(?:""(?<1>[/\a-z0-9_][^""]*)""|'(?<1>[/\a-z0-9_][^']*)'
|(?<1>[/\a-z0-9_]\S*))(\s[^>]*)?>(?<2>.*?)</a>", RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.Compiled);
            string TwoStr = "";
            for (Match m = RegExFindHref.Match(getString); m.Success; m = m.NextMatch())
            {
                TwoStr = m.Groups[1].ToString();
            }

            getString = "";
            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(TwoStr);

            httpWebRequest.ContentType = "application/x-www-form-urlencoded";
            httpWebRequest.Accept =
                "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";

            httpWebRequest.UserAgent =
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";

            //自动跳转。。。
            httpWebRequest.AllowAutoRedirect = false;
            httpWebRequest.KeepAlive = true;
            httpWebRequest.CookieContainer = LoginCookies;
            httpWebRequest.Method = "GET";
            webResponse = (HttpWebResponse)httpWebRequest.GetResponse();
             _APSNET_SessionValue = webResponse.Cookies.Count;

            getStream = webResponse.GetResponseStream();
            streamReader = new StreamReader(getStream, Encoding.GetEncoding("gb2312"));  //Encoding.GetEncoding("gb2312")    Encoding.GetEncoding("utf-8")
            getString = streamReader.ReadToEnd();           
            streamReader.Close();
            getStream.Close();
            
            //*********************************获取cookie
            RegExFindHref = new Regex(@"<a\s+([^>]*\s*)?href\s*=\s*(?:""(?<1>[/\a-z0-9_][^""]*)""|'(?<1>[/\a-z0-9_][^']*)'
|(?<1>[/\a-z0-9_]\S*))(\s[^>]*)?>(?<2>.*?)</a>", RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.Compiled);
            string ht = "";
            for (Match m = RegExFindHref.Match(getString); m.Success; m = m.NextMatch())
            {
                ht = "http://agt.ibc88.com" + System.Web.HttpUtility.UrlDecode(m.Groups[1].ToString());
            }
            ht = ht.Replace("amp;", "");
            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(ht);          

            httpWebRequest.ContentType = "application/x-www-form-urlencoded";
            httpWebRequest.Accept =
                "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";
            httpWebRequest.UserAgent =
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
            httpWebRequest.Method = "Get";
            //自动跳转。。。      
            httpWebRequest.AllowAutoRedirect = false;
            httpWebRequest.KeepAlive = true;           
            httpWebRequest.CookieContainer = LoginCookies;

            webResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            _APSNET_SessionValue = webResponse.Cookies.Count;

            string sdfff = webResponse.Cookies[0].Name + "：" + webResponse.Cookies[0].Value;

            getStream = webResponse.GetResponseStream();
            streamReader = new StreamReader(getStream, Encoding.GetEncoding("gb2312"));
            getString = streamReader.ReadToEnd();

            cookie = webResponse.Headers.Get("Set-Cookie");
            LoginCookies.SetCookies(httpWebRequest.RequestUri, "rpt_bold=1; " + cookie);

            streamReader.Close();
            getStream.Close();

            return getString;
        }

        /// <summary> 
        /// Post模式浏览 
        /// </summary> 
        /// <param name="server">服务器地址 </param> 
        /// <param name="URL">网址 </param> 
        /// <param name="byteRequest">流 </param> 
        /// <param name="cookie">cookie </param> 
        /// <param name="header">句柄 </param> 
        /// <returns> </returns> 
        public static byte[] GetHtmlByBytes(string server, string URL, byte[] byteRequest, string cookie, out string header)
        {
            long contentLength;
            HttpWebRequest httpWebRequest;
            HttpWebResponse webResponse;
            Stream getStream;
            StreamReader streamReader;

            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(URL);
            //CookieContainer co = new CookieContainer();
            //co.SetCookies(new Uri(server), cookie);

            LoginCookies.SetCookies(new Uri(server), cookie);

            httpWebRequest.CookieContainer = LoginCookies;
            LoginCookies = httpWebRequest.CookieContainer;
            httpWebRequest.ContentType = "application/x-www-form-urlencoded";
            httpWebRequest.Accept =
                "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";
            httpWebRequest.Referer = server;
            httpWebRequest.UserAgent =
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
            httpWebRequest.Method = "Post";
            httpWebRequest.AllowAutoRedirect = false; 
            httpWebRequest.ContentLength = byteRequest.Length;
            Stream stream;
            stream = httpWebRequest.GetRequestStream();
            stream.Write(byteRequest, 0, byteRequest.Length);
            stream.Close();
            webResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            header = webResponse.Headers.ToString();
            getStream = webResponse.GetResponseStream();
            contentLength = webResponse.ContentLength;
                                 
            byte[] outBytes = new byte[contentLength];
            outBytes = ReadFully(getStream);
            getStream.Close();
            return outBytes;
        }
        public static byte[] ReadFully(Stream stream)
        {
            byte[] buffer = new byte[128];
            using (MemoryStream ms = new MemoryStream())
            {
                while (true)
                {
                    int read = stream.Read(buffer, 0, buffer.Length);
                    if (read <= 0)
                        return ms.ToArray();
                    ms.Write(buffer, 0, read);
                }
            }
        }

        /// <summary> 
        /// Get模式 
        /// </summary> 
        /// <param name="URL">网址 </param> 
        /// <param name="cookie">cookies </param> 
        /// <param name="header">句柄 </param> 
        /// <param name="server">服务器 </param> 
        /// <param name="val">服务器 </param> 
        /// <returns> </returns> 
        public static string GetHtml(string URL, string cookie, out string header, string server)
        {
            return GetHtml(URL, cookie, out header, server, "");
        }
        /// <summary> 
        /// Get模式浏览 
        /// </summary> 
        /// <param name="URL">Get网址 </param> 
        /// <param name="cookie">cookie </param> 
        /// <param name="header">句柄 </param> 
        /// <param name="server">服务器地址 </param> 
        /// <param name="val"> </param> 
        /// <returns> </returns> 
        public static string GetHtml(string URL, string cookie, out string header, string server, string val)
        {
            HttpWebRequest httpWebRequest;
            HttpWebResponse webResponse;
            Stream getStream;
            StreamReader streamReader;
            string getString = "";
            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(URL);
            httpWebRequest.Accept = "*/*";
            httpWebRequest.Referer = server;
            //CookieContainer co = new CookieContainer();
            ////co.SetCookies(new Uri(server), cookie);
            //httpWebRequest.CookieContainer = co;
            httpWebRequest.UserAgent =
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
            httpWebRequest.Method = "GET";
            webResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            header = webResponse.Headers.ToString();
            getStream = webResponse.GetResponseStream();
            streamReader = new StreamReader(getStream, Encoding.GetEncoding("gb2312"));
            getString = streamReader.ReadToEnd();

            streamReader.Close();
            getStream.Close();
            return getString;
        }
        /// <summary> 
        /// 返回验证码图片流 
        /// </summary> 
        /// <param name="server">服务器地址 </param> 
        /// <param name="URL">验证码网址 </param> 
        /// <param name="cookie">cookie </param> 
        /// <returns> </returns> 
        public static Stream GetStreamByBytes(string server, string URL, string cookie)
        {
            Stream stream = GetCode(server, URL, cookie);
            return stream;
        }

        /// <summary> 
        /// //获取验证码 
        /// </summary> 
        /// <param name="server">服务器地址 </param> 
        /// <param name="url">验证码网址 </param> 
        /// <param name="cookie">cookie </param> 
        /// <returns> </returns> 
        public static Stream GetCode(string server, string url, string cookie)
        {

            HttpWebRequest httpWebRequest;

            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);
            CookieContainer co = new CookieContainer();
            co.SetCookies(new Uri(server), cookie);
            httpWebRequest.CookieContainer = co;

            HttpWebResponse response = (HttpWebResponse)httpWebRequest.GetResponse();
            Stream stream = response.GetResponseStream();
            return stream;

        }
        /// <summary> 
        /// 获取html 
        /// </summary> 
        /// <param name="server"> </param> 
        /// <param name="url"> </param> 
        /// <param name="cookie"> </param> 
        /// <returns> </returns> 

        public static string GetUser(string server, string url, string cookie)
        {
            string getString = "";
            try
            {
                HttpWebRequest httpWebRequest;
                StreamReader streamReader;


                httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);
                CookieContainer co = new CookieContainer();
                co.SetCookies(new Uri(server), cookie);
                httpWebRequest.CookieContainer = co;

                HttpWebResponse response = (HttpWebResponse)httpWebRequest.GetResponse();

                Stream stream = response.GetResponseStream();


                streamReader = new StreamReader(stream, Encoding.GetEncoding("gb2312"));
                getString = streamReader.ReadToEnd();


                try
                {
                    httpWebRequest.GetResponse().Close();
                }
                catch (WebException ex)
                {
                    throw ex;
                }
                streamReader.Close();
                stream.Close();

            }
            catch
            {
            }
            return getString;

        }

    }

}