C#：用HttpWebRequest和HttpWebResponse模拟登录网站（用户名、密码）

HttpWebRequest request = null;
string url = "http://?????.com/SvltLogin";
request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "POST";
request.Accept = "*/*;";
request.UserAgent = "Mozilla/5.0";
request.ContentType = "application/x-www-form-urlencoded";
request.AllowAutoRedirect = true;
request.KeepAlive = true;

string postData = string.Format("txtUsr_id=00000001&txtPassword=mima"); 
byte[] postdatabyte = Encoding.GetEncoding("gbk").GetBytes(postData);
request.ContentLength = postdatabyte.Length;
using (Stream stream = request.GetRequestStream())
{
	stream.Write(postdatabyte, 0, postdatabyte.Length);
}

HttpWebResponse response = (HttpWebResponse)request.GetResponse();

string strWebData = string.Empty;
using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("gbk")))
{
	strWebData = reader.ReadToEnd();
}
richTextBox1.Text = strWebData;