c#抓取网页有时是乱码，有时是好的，求教高手
WebRequest wrq = WebRequest.Create(webaddr);
WebResponse wrs = wrq.GetResponse();
Stream strm = wrs.GetResponseStream();
StreamReader sr_1 = new StreamReader(strm,System.Text.Encoding.GetEncoding("gb2312"));
pagedata_1 = sr_1.ReadToEnd();

上面是代码，pagedata_1有时读到的是乱码，有时可以读到数据，试了很多编码，问题一直未解决，请教高手，怎样才能稳定可靠地读到网页中的数据？万分感谢
[解决办法]
public static string GetEncoding(string Url)
{
try
{
HttpWebRequest myHttpWebRequest = (HttpWebRequest)HttpWebRequest.Create(Url);
myHttpWebRequest.AllowAutoRedirect = false;
HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse();
myHttpWebResponse.Close();
return Regex.Match(myHttpWebResponse.Headers.Get("Content-Type"), @"(?is)(?<=char\-?set[:=])\S+").Value;
}
catch { return ""; }
}
[解决办法]

using (HttpWebResponse response = (HttpWebResponse)webrequest.GetResponse())
                {

                    if (response.ContentEncoding.ToLower().Contains("gzip"))
                    {
                        using (GZipStream stream = new GZipStream(response.GetResponseStream(), CompressionMode.Decompress))
                        {
                            using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
                            {

                                model.html = reader.ReadToEnd();
                            }
                        } 
 
                    }
                    else if (response.ContentEncoding.ToLower().Contains("deflate"))
                    {
                        using (DeflateStream stream = new DeflateStream(response.GetResponseStream(), CompressionMode.Decompress))
                        {
                            using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
                            {

                                model.html = reader.ReadToEnd();
                            }

                        }
                    }
                    else
                    {
                        using (Stream stream = response.GetResponseStream())
                        {
                            using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
                            {

                                model.html = reader.ReadToEnd();
                            }
                        }
                    }
                }