一开始使用WebBrowser.Document.Cookie获取，怎么获取这个值都是null，但是使用http分析工具抓到的包里就都能够看到ASP.NET_SessionId等Cookie值

用了很多办法都不行，下面的方法可以，Mark~

  [DllImport("wininet.dll", CharSet = CharSet.Auto, SetLastError = true)]
        static extern bool InternetGetCookieEx(string pchURL, string pchCookieName, StringBuilder pchCookieData, ref int pcchCookieData, int dwFlags, object lpReserved);

        private static string GetCookieString(string url)
        {
            // Determine the size of the cookie   
            int datasize = 256;
            StringBuilder cookieData = new StringBuilder(datasize);

            if (!InternetGetCookieEx(url, null, cookieData, ref datasize, 0x00002000, null))
            {
                if (datasize < 0)
                    return null;

                // Allocate stringbuilder large enough to hold the cookie   
                cookieData = new StringBuilder(datasize);
                if (!InternetGetCookieEx(url, null, cookieData, ref datasize, 0x00002000, null))
                    return null;
            }
            return cookieData.ToString();
        }