如何使用HttpWebRequest、HttpWebResponse模拟浏览器抓取网页内容

public string GetHtml(string url, Encoding ed)
        {
            string Html = string.Empty;//初始化新的webRequst
            HttpWebRequest Request = (HttpWebRequest)WebRequest.Create(url);

            Request.KeepAlive = true;
            Request.ProtocolVersion = HttpVersion.Version11;
            Request.Method = "GET";
            Request.Accept = "*/* ";
            Request.UserAgent = "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.56 Safari/536.5";
            Request.Referer = url;

            HttpWebResponse htmlResponse = (HttpWebResponse)Request.GetResponse();
            //从Internet资源返回数据流
            Stream htmlStream = htmlResponse.GetResponseStream();
            //读取数据流
            StreamReader weatherStreamReader = new StreamReader(htmlStream, ed);
            //读取数据
            Html = weatherStreamReader.ReadToEnd();
            weatherStreamReader.Close();
            htmlStream.Close();
            htmlResponse.Close();
            //针对不同的网站查看html源文件
            return Html;
        }

        public string GetHtml(string url)
        {
            return GetHtml(url, Encoding.UTF8);
        }