c# - 将 WebClient 与 cookie 一起使用

Question

我正在使用 WebClient 尝试访问网页。我必须先登录，然后网站设置 cookie。我正在使用这个问题 的代码 cookie 设置正确，但是当我尝试访问第二个页面时，我只是返回到登录页面。

private WebClientEx client;
public string GetFile(string URL)
    {
        Login();
        // Download desired page
        return client.DownloadString(URL);
    }

    private void Login()
    {
        using (client)
        {
            var values = new NameValueCollection
            {
                { "Login", "xxxx" },
                { "Password", "xxxx" },
            };
            // Authenticate
            client.UploadValues("http://www.xxxxxx.com/backoffice/login.php");
        }
        return;
    }
}


/// <summary>
/// A custom WebClient featuring a cookie container
/// </summary>
public class WebClientEx : WebClient
{
    public CookieContainer CookieContainer { get; private set; }

    public WebClientEx()
    {
        CookieContainer = new CookieContainer();
    }

    protected override WebRequest GetWebRequest(Uri address)
    {
        WebRequest request = base.GetWebRequest(address);

        if (request.GetType() == typeof(HttpWebRequest))
            ((HttpWebRequest)request).CookieContainer = CookieContainer;

        return request;
    }
}