C#如何HttpWebRequest模拟登陆，获取服务端返回Cookie以便登录请求后使用

public static string GetCookie(string requestUrlString, Encoding encoding, ref CookieContainer cookie)
{
//向服务端请求
HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(requestUrlString);
myRequest.ContentType = "application/x-www-form-urlencoded";
myRequest.CookieContainer = new CookieContainer();
//将请求的结果发送给客户端(界面、应用)
HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();
cookie.Add(myResponse.Cookies);
StreamReader reader = new StreamReader(myResponse.GetResponseStream(), encoding);
return reader.ReadToEnd();
}

public static string GetHtml(string requestUrlString, Encoding encoding, CookieContainer cookie)
{
string ua = "Mozilla/5.0 (Linux; U; Android 2.2; en-us; Nexus One Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1";
HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(requestUrlString);
myRequest.ContentType = "application/x-www-form-urlencoded";
myRequest.UserAgent = ua;
myRequest.CookieContainer = cookie;
HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();
StreamReader reader = new StreamReader(myResponse.GetResponseStream(), encoding);
return reader.ReadToEnd();
}

public static string PostLogin(string postData, string requestUrlString, ref CookieContainer cookie)
{
ASCIIEncoding encoding = new ASCIIEncoding();
byte[] data = encoding.GetBytes(postData);
//向服务端请求
HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(requestUrlString);
myRequest.Method = "POST";
myRequest.ContentType = "application/x-www-form-urlencoded";
myRequest.ContentLength = data.Length;
myRequest.CookieContainer = new CookieContainer();
Stream newStream = myRequest.GetRequestStream();
newStream.Write(data, 0, data.Length);
newStream.Close();
//将请求的结果发送给客户端(界面、应用)
HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();
cookie.Add(myResponse.Cookies);
StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
return reader.ReadToEnd();
}

public static string PostRequest(string postData, string requestUrlString, CookieContainer cookie)
{
ASCIIEncoding encoding = new ASCIIEncoding();
byte[] data = encoding.GetBytes(postData);
HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(requestUrlString);
myRequest.Method = "POST";
myRequest.ContentType = "application/x-www-form-urlencoded";
myRequest.ContentLength = data.Length;
myRequest.CookieContainer = cookie;
Stream newStream = myRequest.GetRequestStream();
newStream.Write(data, 0, data.Length);
newStream.Close();
HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();
StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
return reader.ReadToEnd();
}