C#根据第三方提供的IP查询服务获取公网外网IP地址

/// <summary>
/// C#根据第三方提供的IP查询服务获取公网外网IP地址
/// </summary>
/// <returns></returns>
public static string GetInterNetIPFromAPI()
{
  //测试OK, 此接口查询速度最快
   var html2 = HttpGetPageHtml("http://www.net.cn/static/customercare/yourip.asp", "gbk");
  var ip2 = GetIPFromHtml(html2);
  if (!String.IsNullOrEmpty(ip2)) return ip2;
  
  //测试OK
   var html1 = HttpGetPageHtml("https://www.ip.cn", "utf-8");
  var ip1 = GetIPFromHtml(html1);
  if (!String.IsNullOrEmpty(ip1)) return ip1;
  
  //测试失败，不提供查询服务，需要购买api服务
   var html3 = HttpGetPageHtml("http://www.ip138.com/ips138.asp", "gbk");
  var ip3 = GetIPFromHtml(html3);
  if (!String.IsNullOrEmpty(ip3)) return ip3;
  
  return "";
}

/// <summary>
/// 获取页面html
/// </summary>
/// <param name="url">请求的地址</param>
/// <param name="encoding">编码方式</param>
/// <returns></returns>
private static string HttpGetPageHtml(string url, string encoding)
{
  string pageHtml = string.Empty;
  try
  {
    using (WebClient MyWebClient = new WebClient())
    {
      Encoding encode = Encoding.GetEncoding(encoding);
      MyWebClient.Headers.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.84 Safari/537.36");
      MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据
       Byte[] pageData = MyWebClient.DownloadData(url); //从指定网站下载数据
       pageHtml = encode.GetString(pageData);
    }
  }
  catch (Exception e)
  {
    
  }
  return pageHtml;
}

/// <summary>
/// 从html中通过正则找到ip信息(只支持ipv4地址)
/// </summary>
/// <param name="pageHtml"></param>
/// <returns></returns>
private static string GetIPFromHtml(String pageHtml)
{
  //验证ipv4地址
   string reg = @"(?:(?:(25[0-5])|(2[0-4]\d)|((1\d{2})|([1-9]?\d)))\.){3}(?:(25[0-5])|(2[0-4]\d)|((1\d{2})|([1-9]?\d)))";
  string ip = "";
  Match m = Regex.Match(pageHtml, reg);
  if (m.Success)
  {
    ip = m.Value;
  }
  return ip;
}

//来源:C/S框架网 | www.csframework.com | QQ:23404761