public static CookieContainer CookieContainers = new CookieContainer();

        public Form1()

        {

            InitializeComponent();

        }



        private void button1_Click(object sender, EventArgs e)

        {

            string username = textBox2.Text.Trim();

            string password = textBox3.Text.Trim();

            string code = textBox4.Text.Trim();

            string data="__VIEWSTATE=dDwtMTg3MTM5OTI5MTs7PhMbjAbINgvvHsvy%2FQdjcw3RMlRn&TextBox1="+username+"&TextBox2="+password+"&TextBox3="+code+"&RadioButtonList1=%D1%A7%C9%FA&Button1=&lbLanguage=";

            string loginurl = "http://xk4.suda.edu.cn/";



            getresponse(loginurl,data);

        }



        private void getresponse(string loginurl,string data)

        {

            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(loginurl);

            req.KeepAlive = true;

            req.Method = "POST";

            req.ContentType = "application/x-www-form-urlencoded";

            req.UserAgent = "User-Agent	Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)";

            req.Accept = "Accept	text/html, application/xhtml+xml, */*";

            req.Timeout = 50000;

            req.AllowAutoRedirect = true;

            req.CookieContainer = CookieContainers;

            

            ASCIIEncoding encoding = new ASCIIEncoding();

            byte[] postBytes = encoding.GetBytes(data);

            req.ContentLength = postBytes.Length;

            Stream st = req.GetRequestStream();

            st.Write(postBytes, 0, postBytes.Length);

            st.Close();