php 禁止页面缓存输出

<?php 
header('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); 
header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . 'GMT'); 
header('Cache-Control: no-cache, must-revalidate'); 
header('Pragma: no-cache'); 
?>