<?php
function cache_browser($interval = 60){  
	$now = time(); 
	$pretty_lmtime = gmdate('D, d M Y H:i:s', $now) . ' GMT';  
	$pretty_extime = gmdate('D, d M Y H:i:s', $now + $interval) . ' GMT';  
	//向后兼容HTTP/1.0  
	header("Last Modified: $pretty_lmtime");  
	header("Expires: $pretty_extime");  
	//支持HTTP/1.1
	header("Cache-Control: private,max-age=$interval,s-maxage=0");  
}
cache_browser(60);
echo date("Y-m-d H:i:s");
?>