c# 获取公网IP

引用Nuget包

HtmlAgilityPack

根据HtmlAgilityPack 获取公网IP

        /// <summary>
        /// 获取本地电脑公网IP
        /// </summary>
        /// <returns></returns>
        public static string GetExtranetIpAddress()
        {
            string ExtranetIp = string.Empty;
            try
            {
                string Url = "https://2021.ip138.com/";
                WebClient webClient = new WebClient();
                webClient.Encoding = UTF8Encoding.UTF8;
                string html = webClient.DownloadString(Url);
                HtmlDocument doc = new HtmlDocument();

                doc.LoadHtml(html);
                //下面的意思是：通过属性id的值，来定位A标签
                IEnumerable<HtmlNode> node = doc.DocumentNode.Descendants("a");
                foreach (var item in node)
                {
                    //获取A标签html文本
                    ExtranetIp = item.InnerText;
                    break;
                }
            }
            catch
            {
                ExtranetIp = "";
            }
            return ExtranetIp;
        }