c#使用WebClient登錄網站抓取登錄後的網頁

C#登錄網站實際上就是模擬瀏覽器提交表單，然後記錄瀏覽器響應返回的會話Cookie值，再次發送請求時帶著這個會話cookie值去請求就可以實現模擬登錄的效果了。

如下類CookieAwareWebClient實現在發送請求時都帶著cookie。

public class CookieAwareWebClient : WebClient
{/* 何問起 hwq2.com */
    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;
    }
}/* 何問起 hovertree.com */

如下是模擬表單提交登錄的使用示例：

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");/* 何問起 hwq2.com */

推薦：http://www.cnblogs.com/roucheng/p/csharpfetch.html