網頁自動登錄（提交Post內容）的用途很多，如驗證身份、程序升級、網絡投票等，以下是用C#實現的方法。
       網頁自動登錄和提交POST信息的核心就是分析網頁的源代碼（HTML），在C#中，可以用來提取網頁HTML的組件比較多，常用的用WebBrowser、WebClient、HttpWebRequest這三個。以下就分別用這三種方法來實現：
      1、WebBrowser是個"迷你"瀏覽器，其特點是Post時不用關心Cookie、內置JS等問題
       WebBrowser是VS2005新提供的組件（其實就是封裝了IE接口），實現POST功能一般在webBrowser的DocumentCompleted中分析HtmlDocument 來實現，代碼如下：
            HtmlElement ClickBtn =null;
           if (e.Url.ToString().ToLower().IndexOf("xxx.htm") > 0)   //登陸頁面
            {
                HtmlDocument doc = webBrowser1.Document;
                for (int i = 0; i < doc.All.Count ; i++)
                {
                    if (doc.All[i].TagName.ToUpper().Equals("INPUT"))
                    {
                        switch (doc.All[i].Name)
                        {
                            case "userCtl":
                                doc.All[i].InnerText = "user01";
                                break;
                            case "passCt1":
                                doc.All[i].InnerText = "mypass";
                                break;
                            case "B1":
                                ClickBtn = doc.All[i]; //提交按鈕
                                break;
                        }
                    }
                }
                ClickBtn.InvokeMember("Click");   //執行按扭操作
            }
 
      2、WebClient封裝了HTTP的一些類，操作簡單，相較于webBrowser，特點是可以自設代理，缺點是對COOKIE的控制
      WebClient的運行全在后臺，并且提供了異步操作的能力，這樣很方便并發多個任務，然后等待結果的返回，再逐個處理。多任務異步調用的代碼如下：
    private void StartLoop(int ProxyNum)
        {
            WebClient [] wcArray = new WebClient[ProxyNum]; //初始化
              for (int idArray = 0; idArray< ProxyNum;idArray++)
            {
                 wcArray[idArray] = new WebClient();
                wcArray[idArray].OpenReadCompleted += new OpenReadCompletedEventHandler(Pic_OpenReadCompleted2);
                wcArray[idArray].UploadDataCompleted += new UploadDataCompletedEventHandler(Pic_UploadDataCompleted2);
                try
                {
                     ......
                    wcArray[idArray].Proxy = new WebProxy(proxy[1], port);
                  wcArray[idArray].OpenReadAsync(new Uri("http://xxxx.com.cn/tp.asp?Id=129")); //打開WEB;
                    proxy = null;
                }
                catch
                {
                }
            }
        }

        private void Pic_OpenReadCompleted2(object sender, OpenReadCompletedEventArgs e)
        {
                if (e.Error == null)
                {
                           string textData = new StreamReader(e.Result, Encoding.Default).ReadToEnd(); //取返回信息
                            .....
                              String cookie = ((WebClient)sender).ResponseHeaders["Set-Cookie"];
                             ((WebClient)sender).Headers.Add("Content-Type", "application/x-www-form-urlencoded");
                            ((WebClient)sender).Headers.Add("Accept-Language", "zh-cn");
                            ((WebClient)sender).Headers.Add("Cookie", cookie);

                            string postData = "......"
                            byte[] byteArray = Encoding.UTF8.GetBytes(postData); // 轉化成二進制數組 
                           ((WebClient)sender).UploadDataAsync(new Uri("http://xxxxxxy.com.cn/tp.asp?Id=129"), "POST", byteArray);
                }
         }

        private void Pic_UploadDataCompleted2(object sender, UploadDataCompletedEventArgs e)
        {
                 if (e.Error == null)
                {
                    string returnMessage = Encoding.Default.GetString(e.Result);
                     ......
                 }
       }
 

      3、HttpWebRequest較為低層，能實現的功能較多，Cookie操作也很簡單

        private bool PostWebRequest()        
        {
                   CookieContainer cc = new CookieContainer();
                    string pos tData = "user=" + strUser + "&pass=" + strPsd;
                    byte[] byteArray = Encoding.UTF8.GetBytes(postData); // 轉化

                    HttpWebRequest webRequest2 = (HttpWebRequest)WebRequest.Create(new Uri("http://www.xxxx.com/chk.asp"));
                    webRequest2.CookieContainer = cc;
                    webRequest2.Method = "POST";
                    webRequest2.ContentType = "application/x-www-form-urlencoded";
                    webRequest2.ContentLength = byteArray.Length;
                    Stream newStream = webRequest2.GetRequestStream();
                    // Send the data.
                    newStream.Write(byteArray, 0, byteArray.Length);    //寫入參數
                    newStream.Close();

                    HttpWebResponse response2 = (HttpWebResponse)webRequest2.GetResponse();
                    StreamReader sr2=new StreamReader(response2.GetResponseStream(), Encoding.Default);
                    string text2 = sr2.ReadToEnd();
                  ......
         }                  
 
              HttpWebRequest同樣提供了異步操作，有興趣的朋友自己查MSDN，實現起來也不難。