HttpWebRequest webrequest = WebRequest.Create("http://passport.csdn.net/account/login") as HttpWebRequest;
        webrequest.ContentType = "application/x-www-form-urlencoded";
        webrequest.CookieContainer = new CookieContainer();
        webrequest.Method = "POST";
        string arg = string.Format("u={0}&p={1}", "tiandiyuzhou1", "abcdefg");
        byte[] data = Encoding.ASCII.GetBytes(arg);
        webrequest.ContentLength = data.Length;
        using (Stream reqStream = webrequest.GetRequestStream())
        {
            reqStream.Write(data, 0, data.Length);
        }
        HttpWebResponse webresponse = webrequest.GetResponse() as HttpWebResponse;
        using (StreamReader reader = new StreamReader(webresponse.GetResponseStream()))
        {
            Response.Write(reader.ReadToEnd());
        }
/*
这里第1点：为什么不管用户密码输入是否正确，返回的都是下面那个图？
怎么获取不到是否登陆成功或失败？
—/
        foreach (Cookie coo in webresponse.Cookies)
            Response.Write(coo.Name + "==" + coo.Value + "<br/>");
/*
这里第2点：我把地址改为http://community.csdn.net/WebNavigation/ForumContent.aspx这个，
为什么获取到的Cookie总是
UserName==
UserInfo==
获取不到value值呢？
*/