PHP controls the page expiration time Code _php skill

Of course, the prerequisite is to open a CDN in a function reload_into_ims on. So the user sent over the No-cache is not afraid. Because it will give No-cache to If-modified-since. So we write the program is mainly to if-modified-since control just fine. Remember, the caching system architecture is best controlled by the backend, so the best approach is to manage the expiration of the program. Oh, I only can php, just write one in PHP, the other program is the same.

See my following procedure, hehe, 5 minutes overdue.

Copy Code code as follows:

<?php
$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);
}
?>