acdsee2009 license code PHP web page expiration time control code

Of course, the prerequisite is to turn on reload_into_ims on, a function in CDN. In this way, users will not be afraid of sending no-cache. Because this will convert no-cache into If-Modified-Since. So we write programs mainly for If-Modified -Since control is fine. Remember, in the cache system architecture, it is best to be controlled by the backend, so the best way is to manage expiration by program. Hehe, I only know PHP, so I will use PHP to write one. The same goes for programs.
See my program below, haha, it expires in 5 minutes.

Copy the code The code is as follows:

$headers = apache_request_headers();
$client_time = (isset($headers[' If-Modified-Since']) ? strtotime($headers['If-Modified-Since']) : 0);
$now=gmmktime();
$now_list=gmmktime()-60*5;
if ( $client_time<$now and $client_time >$now_list){
header('Last-Modified: '.gmdate('D, d M Y H:i:s', $client_time).' GMT', true, 304);
exit(0);
}else{
header('Last-Modified: '.gmdate('D, d M Y H:i:s', $now).' GMT', true, 200);
}
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