string strUrl = "http://www.ip138.com/ip2city.asp"; //获得IP的网址了   
            Uri uri = new Uri(strUrl);   
            WebRequest wr = WebRequest.Create(uri);   
            Stream s = wr.GetResponse().GetResponseStream();   
            StreamReader sr = new StreamReader(s, Encoding.Default);   
            string all = sr.ReadToEnd(); //读取网站的数据   
            int i = all.IndexOf("[") + 1;   
            string tempip = all.Substring(i, 15);   
            string ip = tempip.Replace("]", "").Replace(" ", "");   
            return ip;