本文实例讲述了C#使用WebClient登录网站并抓取登录后的网页信息实现方法。分享给大家供大家参考，具体如下：
C#登录网站实际上就是模拟浏览器提交表单，然后记录浏览器响应返回的会话Cookie值，再次发送请求时带着这个会话cookie值去请求就可以实现模拟登录的效果了。
如下类CookieAwareWebClient实现在发送请求时都带着cookie。
public class CookieAwareWebClient : WebClient
{
private CookieContainer cookie = new CookieContainer();
protected override WebRequest GetWebRequest(Uri address)
{
WebRequest request = base.GetWebRequest(address);
if (request is HttpWebRequest)
{
(request as HttpWebRequest).CookieContainer = cookie;
}
return request;
}
}
如下是模拟表单提交登录的使用示例：
var client = new CookieAwareWebClient();
client.BaseAddress = @"https://hovertree.net/any/base/url/";
var loginData = new NameValueCollection();
loginData.Add("login", "YourLogin");
loginData.Add("password", "YourPassword");
client.UploadValues("login.php", "POST", loginData);
//Now you are logged in and can request pages
string htmlSource = client.DownloadString("index.php");
希望本文所述对大家C#程序设计有所帮助。
