ASP.NET获取客户端IP方法

string requestClientIpAddress = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (string.IsNullOrEmpty(requestClientIpAddress))
 requestClientIpAddress = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
if (string.IsNullOrEmpty(requestClientIpAddress))
 requestClientIpAddress = HttpContext.Current.Request.UserHostAddress;