简单的IPHelper.cs 访客IP获取类

public class IPHelper
{
    public static string GetVisitorsIPAddress()
    {
        string result = String.Empty;
 
        result = System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
 
        // 如果使用代理，获取真实IP
        if (result != null && result.IndexOf(".") == -1)    //没有“.”肯定是非IPv4格式
            result = null;
        else if (result != null)
        {
            if (result.IndexOf(",") != -1)
            {
                //有“,”，估计多个代理。取第一个不是内网的IP。
                result = result.Replace(" ", "").Replace("'", "");
                string[] temparyip = result.Split(",;".ToCharArray());
                for (int i = 0; i < temparyip.Length; i++)
                {
                    if (IsIPAddress(temparyip[i])
                        && temparyip[i].Substring(0, 3) != "10."
                        && temparyip[i].Substring(0, 7) != "192.168"
                        && temparyip[i].Substring(0, 7) != "172.16.")
                    {
                        return temparyip[i];    //找到不是内网的地址
                    }
                }
            }
            else if (IsIPAddress(result)) //代理即是IP格式
                return result;
            else
                result = null;    //代理中的内容 非IP，取IP
        }
        if (null == result || result == String.Empty)
            result = System.Web.HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
 
        if (result == null || result == String.Empty)
            result = System.Web.HttpContext.Current.Request.UserHostAddress;
 
        return result;
    }
 
    /// <summary>
    /// 判断是否是IP地址格式 0.0.0.0
    /// </summary>
    /// <param name="str1">待判断的IP地址</param>
    /// <returns>true or false</returns>
    private static bool IsIPAddress(string str1)
    {
        if (str1 == null || str1 == string.Empty || str1.Length < 7 || str1.Length > 15) return false;
 
        string regformat = @"^\d{1,3}[\.]\d{1,3}[\.]\d{1,3}[\.]\d{1,3}$";
 
        Regex regex = new Regex(regformat, RegexOptions.IgnoreCase);
        return regex.IsMatch(str1);
    }
}