获取用户的ip

public  function getClientIP()
    {
        if (isset($_SERVER)) {
            if (isset($_SERVER["HTTP_X_FORWARDED_FOR"])) {
                $realip = $_SERVER["HTTP_X_FORWARDED_FOR"];
            } else 
                if (isset($_SERVER["HTTP_CLIENT_IP"])) {
                    $realip = $_SERVER["HTTP_CLIENT_IP"];
                } else {
                    $realip = $_SERVER["REMOTE_ADDR"];
                }
        } else {
            if (getenv("HTTP_X_FORWARDED_FOR")) {
                $realip = getenv("HTTP_X_FORWARDED_FOR");
            } else 
                if (getenv("HTTP_CLIENT_IP")) {
                    $realip = getenv("HTTP_CLIENT_IP");
                } else {
                    $realip = getenv("REMOTE_ADDR");
                }
        }

        return addslashes($realip);
    }