蜘蛛抓取页面的转码问题

public class Network
{
    /// 获得页面的html代码
    /// </summary>
    /// <paramname='url'>页面地址</param>
    public static string GetHtml(string url)
    {
        string html = '';
        try
        {
           WebClient MyWebClient = new WebClient();

           Encoding utf8 = Encoding.UTF8;

           Encoding defaultCode = Encoding.Default;

           MyWebClient.Credentials =CredentialCache.DefaultCredentials;//获取或设置用于对向Internet资源的请求进行身份验证的网络凭据
        }
    }