用asp.net c# HttpWebRequest获取网页源代码

该方法需要传递目标网页的编码方式，比如System.Text.Encoding.Default或者System.Text.Encoding.UTF8

如果哪位高手知道如何自动判断目标页面的编码格式，请在评论中告知。谢谢！

/// <summary>

        /// 获取源代码

        /// </summary>

        /// <param name="url"></param>

        /// <param name="encoding"></param>

        /// <returns></returns>

        public static string GetPage(string url, Encoding encoding)

        {

            HttpWebRequest request = null;

            HttpWebResponse response = null;

            StreamReader reader = null;

            try

            {

                request = (HttpWebRequest)WebRequest.Create(url);

                request.UserAgent = "www.svnhost.cn";

                request.Timeout = 20000;

                request.AllowAutoRedirect = false;



                response = (HttpWebResponse)request.GetResponse();

                if (response.StatusCode == HttpStatusCode.OK && response.ContentLength < 1024 * 1024)

                {

                    reader = new StreamReader(response.GetResponseStream(), encoding);

                    string html = reader.ReadToEnd();



                    return html;

                }

            }

            catch

            {

            }

            finally

            {



                if (response != null)

                {

                    response.Close();

                    response = null;

                }

                if (reader != null)

                    reader.Close();



                if (request != null)

                    request = null;



            }



            return string.Empty;

        }