PHP获取真实的ip地址

 public static function get_real_ip()
    {
        if (isset($_SERVER)) {
            static $realip = NULL;
            if ($realip !== NULL) {
                return $realip;
            }
            if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) { //阿里云接入云盾高防,第一个值是用户真实IP,后面的值都是代理IP,包括HTTP_X_REAL_IP都有可能(运营商不同)是代理IP
                $arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
                /* 取X-Forwarded-For中第一个非unknown的有效IP字符串 */
                foreach ($arr AS $ip) {
                    $ip = trim($ip);
                    if ($ip != 'unknown') {
                        $realip = $ip;
                        break;
                    }
                }
            } elseif (isset($_SERVER['HTTP_X_REAL_IP'])) {
                $realip = $_SERVER['HTTP_X_REAL_IP'];
            } elseif (isset($_SERVER['REMOTE_ADDR'])) {
                $realip = $_SERVER['REMOTE_ADDR'];
            } elseif (isset($_SERVER['HTTP_CLIENT_IP'])) {
                $realip = $_SERVER['HTTP_CLIENT_IP'];
            } else {
                $realip = '0.0.0.0';
            }
        } else {
            if (getenv('REMOTE_ADDR')) {
                $realip = getenv('REMOTE_ADDR');
            } elseif (getenv('HTTP_X_FORWARDED_FOR')) {
                $realip = getenv('HTTP_X_FORWARDED_FOR');
            } else {
                $realip = getenv('HTTP_CLIENT_IP');
            }
        }
        preg_match("/[\d\.]{7,15}/", $realip, $onlineip);
        $realip = !empty($onlineip[0]) ? $onlineip[0] : '0.0.0.0';
        return $realip;
    }