C#模拟用户登录，数据抓取

        /// <summary>
        /// HTML数据返回
        /// </summary>
        /// <param name="PageCount"></param>
        /// <returns></returns>
        private string Get12345FormCode()
        {

            Dictionary<string, string> postParams = new Dictionary<string, string>();
            postParams.Add("__EVENTTARGET", "btnLogin");
            postParams.Add("__EVENTARGUMENT", "");
            postParams.Add("__VIEWSTATE", "/wEPDwUKMTQ3ODc3MDg4Nw9kFgICAw9kFgICAw8PZBYCHgV2YWx1ZQUgOUJGMzk5RjUyQTJDN0JFMDMyNURDQUREMDY3RTA4REVkGAEFHl9fQ29udHJvbHNSZXF1aXJlUG9zdEJhY2tLZXlfXxYBBQdjYlRydXN0JK18zzTQsBhXx3/E/THqcjXiDMtvMA5/xVWK6vwjVZk=");

            postParams.Add("__EVENTVALIDATION", "/wEWBgL7/qTPBwL64ITXCAKT/Zj2BALg0rm0AwLR5qxWAoLch4YMUR4smh/9EOUQ9f0Eg0KWSFu1KOyQeWNxVFQei1Jfb6w=");
            postParams.Add("txbAccount", "admin_pjcg");
            postParams.Add("txbPassword", "pjcg.12345");
            postParams.Add("cbTrust", "on");
            postParams.Add("rmk", "9BF399F52A2C7BE0325DCADD067E08DE");

            //登陆地址
            string getViewStateAndEventValidationLoginUrl = "http://113.107.142.14:12345/login.aspx";
            //目标地址
            string getDataUrl = "http://113.107.142.14:12345/app/Deal/Pages/replylist.aspx";
            try
            {
                CookieContainer cookieContainer = new CookieContainer();

                ///////////////////////////////////////////////////  
                // 1.打开 MyLogin.aspx 页面，获得 GetVeiwState & EventValidation  
                ///////////////////////////////////////////////////                  
                // 设置打开页面的参数  
                HttpWebRequest request = WebRequest.Create(getViewStateAndEventValidationLoginUrl) as HttpWebRequest;
                request.Method = "GET";
                request.KeepAlive = false;
                request.AllowAutoRedirect = false;

                // 接收返回的页面  
                HttpWebResponse response = request.GetResponse() as HttpWebResponse;
                System.IO.Stream responseStream = response.GetResponseStream();
                System.IO.StreamReader reader = new System.IO.StreamReader(responseStream, Encoding.UTF8);
                string srcString = reader.ReadToEnd();


                ///////////////////////////////////////////////////  
                // 2.自动填充并提交 Login.aspx 页面，提交Login.aspx页面，来保存Cookie  
                ///////////////////////////////////////////////////  


                // 要提交的字符串数据。格式形如:user=uesr1&password=123  
                string postString = "";
                foreach (KeyValuePair<string, string> de in postParams)
                {
                    //把提交按钮中的中文字符转换成url格式，以防中文或空格等信息  
                    postString += System.Web.HttpUtility.UrlEncode(de.Key.ToString()) + "=" + System.Web.HttpUtility.UrlEncode(de.Value.ToString()) + "&";
                }

                // 将提交的字符串数据转换成字节数组  
                byte[] postData = Encoding.ASCII.GetBytes(postString);

                // 设置提交的相关参数  
                request = WebRequest.Create(getViewStateAndEventValidationLoginUrl) as HttpWebRequest;
                request.Method = "POST";
                request.KeepAlive = false;
                request.ContentType = "application/x-www-form-urlencoded";
                request.CookieContainer = cookieContainer;
                request.ContentLength = postData.Length;
                request.AllowAutoRedirect = false;

                // 提交请求数据  
                System.IO.Stream outputStream = request.GetRequestStream();
                outputStream.Write(postData, 0, postData.Length);
                outputStream.Close();

                // 接收返回的页面  
                response = request.GetResponse() as HttpWebResponse;
                responseStream = response.GetResponseStream();
                reader = new System.IO.StreamReader(responseStream, Encoding.UTF8);
                srcString = reader.ReadToEnd();

                ///////////////////////////////////////////////////  
                // 3.打开需要抓取数据的页面  
                ///////////////////////////////////////////////////  
                // 设置打开页面的参数  
                request = WebRequest.Create(getDataUrl) as HttpWebRequest;
                request.Method = "GET";
                request.KeepAlive = false;
                request.CookieContainer = cookieContainer;

                // 接收返回的页面  
                response = request.GetResponse() as HttpWebResponse;
                responseStream = response.GetResponseStream();
                reader = new System.IO.StreamReader(responseStream, Encoding.UTF8);
                srcString = reader.ReadToEnd();
                return srcString;
                ///////////////////////////////////////////////////  
                // 4.分析返回的页面  
                ///////////////////////////////////////////////////  
                // ...... ......  
            }
            catch (WebException we)
            {
                string msg = we.Message;
                return msg;
            }
               
        }