php获取客户端ip

    /**
     * 获取访问者IP
     *
     */
    public static function get_client_ip() {
        if (getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), 'unknown')) {
            $CLIENT_IP = getenv('HTTP_CLIENT_IP');
        } elseif (getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), 'unknown')) {
            $CLIENT_IP = getenv('HTTP_X_FORWARDED_FOR');
        } elseif (getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), 'unknown')) {
            $CLIENT_IP = getenv('REMOTE_ADDR');
        } elseif (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], 'unknown')) {
            $CLIENT_IP = $_SERVER['REMOTE_ADDR'];
        }
        return $CLIENT_IP;
    }