picturebox加载图片的三种方法与网站验证码的抓取

//默认页面请求
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(DefaultUrl);
            request.Method = "GET";
            request.ContentType = "application/x-www-form-urlencoded";
            request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:5.0.1) Gecko/20100101 Firefox/5.0.1";
            request.Accept = "image/webp,*/*;q=0.8";
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            Stream stream = response.GetResponseStream();
            string WebContent = new StreamReader(stream, System.Text.Encoding.UTF8).ReadToEnd();
            //验证码请求
            request = (HttpWebRequest)WebRequest.Create(CodeUrl);
            request.Method = "GET";
            request.ContentType = "application/x-www-form-urlencoded";
            request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:5.0.1) Gecko/20100101 Firefox/5.0.1";
            request.Accept = "image/webp,*/*;q=0.8";
            request.CookieContainer = lCC;//!Very Important.!!!
            response = (HttpWebResponse)request.GetResponse();
            response.Cookies = lCC.GetCookies(request.RequestUri);
            stream = response.GetResponseStream();
            picCode.Image = Image.FromStream(stream);
            //stream.Dispose();