public static  string AutoHtml(string url)
      {
          if (url.ToLower().IndexOf("http://")==-1)
          {
              url = "http://" + url;
          }
          WebClient myWebClient = new WebClient();
          myWebClient.Credentials = CredentialCache.DefaultCredentials;
          byte[] myDataBuffer = null;
          try
          {
             myDataBuffer=myWebClient.DownloadData(url);
          }
          catch { return null; }
         //
          string dd = System.Text.Encoding.UTF8.GetString(myDataBuffer);
         //
         
          string strWebData = Encoding.Default.GetString(myDataBuffer);
         // strWebData = " <title></title><meta  charset=gb2312 />";
         // string strRegex = @"charset=['""]?(.*?)['""]?\r\n/>";
          //Match charSetMatchs = Regex.Match(strWebData, strRegex, RegexOptions.IgnoreCase); 
          //Regex r = new Regex(strRegex, RegexOptions.IgnoreCase);
          //MatchCollection m = r.Matches(strWebData);
          //获取网页字符编码描述信息
          Match charSetMatch = Regex.Match(strWebData, @"charset=['""]?(.*?)['""]?\s?/>", RegexOptions.IgnoreCase); 
          string webCharSet = charSetMatch.Groups[1].Value;
          if (string.IsNullOrEmpty(webCharSet))
          {
              webCharSet = "utf-8";
          }   //换一个编码
          strWebData = Encoding.GetEncoding(webCharSet).GetString(myDataBuffer);
          return strWebData;
      }