MVC4 获取IP

private string GetClientIp(HttpRequestMessage request){    if (request.Properties.ContainsKey("MS_HttpContext"))    {        return ((HttpContextWrapper)request.Properties["MS_HttpContext"]).Request.UserHostAddress;    }    else if (request.Properties.ContainsKey(RemoteEndpointMessageProperty.Name))    {        RemoteEndpointMessageProperty prop;        prop = (RemoteEndpointMessageProperty)this.Request.Properties[RemoteEndpointMessageProperty.Name];        return prop.Address;    }    else    {        return null;    }}