string postData="__VIEWSTATE=/wEPDwUKLTcxMDYwMzYwNGRkIr9b9tytd6ITkVMabkIG5x3FrHc=& amp;companyName=&loginSubmit=%E7%99%BB%E5%BD%95&loginname=& loginpwd=&loginSubmit=登录";

//我用get的方式获取不到,索性把账号密码都制空,让它报错,

string url="http://vip.fang.58.com/login.aspx";

HttpWebRequest request;
            HttpWebResponse response = null;
            string msg = "";
            byte[] b = null;
            b = Encoding.UTF8.GetBytes(postData);
           
            request = WebRequest.Create(url) as HttpWebRequest;
            request.CookieContainer = new CookieContainer();
            request.Method = "POST";
            request.Timeout = 30000;
            request.AllowAutoRedirect = true;
            request.ContentType = "text/html; charset=utf-8";
            request.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.13) Gecko/20101203 AlexaToolbar/alxf-2.0 Firefox/3.6.13";
            request.Accept = "text/html,application/xhtml xml,application/xml;q=0.9,*/*;q=0.8";
            //request.Headers.Add("Accept-Language", "zh-CN");
            //request.Headers.Add("Accept-Encoding", "gzip, deflate");
            request.KeepAlive = false;

            request.ContentLength = b.Length;
            using (Stream stream = request.GetRequestStream())
            {
                stream.Write(b, 0, b.Length);
            }

            try
            {
                using (response = request.GetResponse() as HttpWebResponse)
                {//这里没有值;
                    string aaa = request.Headers.Get("Set-Cookie");
                    using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
                    {
                        msg = reader.ReadToEnd();
//这里是0;
                        if (response.Cookies.Count > 0)
                        {
                            cookie.Add(response.Cookies);
                        }
                        if (msg.Contains(str))
                        {
                            return true;
                        }
                        else
                        {
                            return false;
                        }
                    }
                }
            }
            catch
            {
                return false;
            }