1. 访问你需要站外提交的页面，比如 CSDN 登陆页 http://www.csdn.net/member/UserLogin.aspx
2. 填写好需要的资料，比如用户名和密码，
3. 打开 Visual Sniffer, 点“开始拦截”
4. 在访问的页面中提交。
5. 等提交成功之后，在 Visual Sniffer 中“停止拦截”
6. 在 Visual Sniffer 的左侧栏的加号中依次点开，右边是它拦截到的内容：
拦截的内容如下
POST http://www.csdn.net/member/UserLogin.aspx HTTP/1.0Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, application/x-shockwave-flash, */*Referer: http://www.csdn.net/member/UserLogin.aspxAccept-Language: zh-cnContent-Type: application/x-www-form-urlencodedUA-CPU: x86Pragma: no-cacheUser-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; InfoPath.1)Host: www.csdn.netContent-Length: 355Proxy-Connection: Keep-AliveCookie: ASPSESSIONIDAAAATBQC=FMEGGCKDBKHAMMCGKPFDMBFG; ASP.NET_SessionId=lusprmnom05lr445tmteaf55; userid=699879__EVENTTARGET=&__EVENTARGUMENT=&__VIEWSTATE=dDwtMTcwMzgxNjQ2Mjs7bDxDU0ROVXNlckxvZ2luOmNiX1NhdmVTdGF0ZTtDU0ROVXNlckxvZ2luOkltYWdlX0xvZ2luOz4%2Btu1q2wmRZoAJTi9L73w1zBleylY%3D&CSDNUserLogin%3Atb_UserName=testusername&CSDNUserLogin%3Atb_Password=testpassword&CSDNUserLogin%3Atb_ExPwd=9232&from=&CSDNUserLogin%3AImage_Login.x=36&CSDNUserLogin%3AImage_Login.y=6GET http://www.csdn.net/mycustompage.htm?aspxerrorpath=/member/UserLogin.aspx HTTP/1.0Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, application/x-shockwave-flash, */*Referer: http://www.csdn.net/member/UserLogin.aspxAccept-Language: zh-cnUA-CPU: x86Pragma: no-cacheUser-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; InfoPath.1)Host: www.csdn.netProxy-Connection: Keep-AliveCookie: ASPSESSIONIDAAAATBQC=FMEGGCKDBKHAMMCGKPFDMBFG; ASP.NET_SessionId=lusprmnom05lr445tmteaf55; userid=699879__EVENTTARGET=&__EVENTARGUMENT=&__VIEWSTATE=dDwtMTcwMzgxNjQ2Mjs7bDxDU0ROVXNlckxvZ2luOmNiX1NhdmVTdGF0ZTtDU0ROVXNlckxvZ2luOkltYWdlX0xvZ2luOz4%2Btu1q2wmRZoAJTi9L73w1zBleylY%3D&CSDNUserLogin%3Atb_UserName=testusername&CSDNUserLogin%3Atb_Password=testpassword&CSDNUserLogin%3Atb_ExPwd=9232
自动登录网站 protected static string cookieHeader; private void Page_Load(object sender, System.EventArgs e) 
{
string strReContent = string.Empty; //登录 strReContent = PostLogin("http://www.mystand.com.cn/login/submit.jsp提交的页面","提交的参数：userid=hgj0000&password=06045369","引用地址：http://www.mystand.com.cn/"); //asp.net登录传递的参数需注意 //strReContent = PostLogin("http://www.mystand.com.cn/login.aspx","__VIEWSTATE=dDwtNjkzMjUyNDczO3Q8O2w8aTwzPjs%2BO2w8dDxwPHA8bDxUZXh0Oz47bDxcZTs%2BPjs%2BOzs%2BOz4%2BOz6aX2dtqkJTK%2BKbNPsjd7Op%2Fl26Iw%3D%3D&txtUserName=hxf&txtPassword=hxf0000&btnEnter=%E7%99%BB%E5%BD%95","http://www.mystand.com.cn/login.aspx"); //获取页面 strReContent = GetPage("http://www.mystand.com.cn/company/getdata.jsp?code=","引用地址：http://www.mystand.com.cn/"); //strReContent = GetPage("http://www.mystand.com.cn/Modules/index.aspx","http://www.mystand.com.cn/login.aspx"); //可以对获得的内容进行处理：strReContent
} /**//// <summary> /// 功能描述：模拟登录页面，提交登录数据进行登录，并记录Header中的cookie /// </summary> /// <param name="strURL">登录数据提交的页面地址</param> /// <param name="strArgs">用户登录数据</param> /// <param name="strReferer">引用地址</param> /// <returns>可以返回页面内容或不返回</returns> public static string PostLogin(string strURL,string strArgs,string strReferer) { string strResult = ""; HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(strURL); myHttpWebRequest.AllowAutoRedirect = true; myHttpWebRequest.KeepAlive = true; myHttpWebRequest.Accept = "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/vnd.ms-excel, application/msword, application/x-shockwave-flash, */*"; myHttpWebRequest.Referer = strReferer; myHttpWebRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 2.0.50727)"; myHttpWebRequest.ContentType = "application/x-www-form-urlencoded"; myHttpWebRequest.Method = "POST"; CookieCollection myCookies = null; CookieContainer myCookieContainer = new CookieContainer(); myHttpWebRequest.CookieContainer = myCookieContainer; Stream MyRequestStrearm = myHttpWebRequest.GetRequestStream(); StreamWriter MyStreamWriter = new StreamWriter(MyRequestStrearm,Encoding.ASCII); //把数据写入HttpWebRequest的Request流 MyStreamWriter.Write(strArgs); //关闭打开对象 MyStreamWriter.Close(); MyRequestStrearm.Close(); HttpWebResponse response = null; System.IO.StreamReader sr = null; response = (HttpWebResponse)myHttpWebRequest.GetResponse(); cookieHeader = myHttpWebRequest.CookieContainer.GetCookieHeader(new Uri(strURL)); HttpContext.Current.Application.Lock(); HttpContext.Current.Application["cookieHeader"] = cookieHeader; HttpContext.Current.Application.UnLock(); myCookies = response.Cookies; sr = new System.IO.StreamReader(response.GetResponseStream(),Encoding.GetEncoding("gb2312")); // //utf-8 strResult = sr.ReadToEnd(); return strResult; } /**//// <summary> /// 功能描述：在PostLogin成功登录后记录下Headers中的cookie，然后获取此网站上其他页面的内容 /// </summary> /// <param name="strURL">获取网站的某页面的地址</param> /// <param name="strReferer">引用的地址</param> /// <returns>返回页面内容</returns> public static string GetPage(string strURL,string strReferer) { string strResult = ""; HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(strURL); myHttpWebRequest.ContentType = "text/html"; myHttpWebRequest.Method = "GET"; myHttpWebRequest.Referer = strReferer; myHttpWebRequest.Headers.Add("cookie:"+ cookieHeader); HttpWebResponse response = null; System.IO.StreamReader sr = null; response = (HttpWebResponse)myHttpWebRequest.GetResponse(); sr = new System.IO.StreamReader(response.GetResponseStream(), Encoding.GetEncoding("gb2312")); // //utf-8 strResult = sr.ReadToEnd(); return strResult; }