/// <summary>    
/// 获取IPv4地址    
/// </summary>    
/// <returns>
</returns>  
public static string GetIP4Address(HttpRequest request = null)    
{      
Func<IPAddress, bool> f = e => e.AddressFamily.ToString() == "InterNetwork";      
IPAddress ipa = Dns.GetHostAddresses((request
?? HttpContext.Current.Request).UserHostAddress).FirstOrDefault(f)        
?? Dns.GetHostAddresses(Dns.GetHostName()).FirstOrDefault(f);      
if (ipa != null)     
{       
return ipa.ToString();    
}      
return HttpContext.Current.Request.UserHostAddress;   
}