php - HTTP header : Expires

Question

Expires Headers are rather simple in how they work. They tell the browser how long to store a file in the cache so subsequent page views and visits they don't have to download the file again. You are right to assume Expires Headers don't improve page speed for a first time visit as this visitor would have to download all the files for the first time. Using Expires Headers helps increase load times for returning visitors

当我运行下面的代码然后在浏览器中检查标题时，过期日期真的让我感到困惑 -> Expires:Thu, 19 Nov 1981 08:52:00 GMT<-，因为我几分钟前创建了这个文件。你能告诉我这是什么意思吗？

<?php 
session_cache_limiter('private');
session_start();  
 ?>

谢谢!

Answer 1

这个日期的意义在于开发此代码的 Sascha Schumann 生日。

您可以从 session.c 更改它:

Authors: Sascha Schumann <sascha@schumann.cx> 
         Andrei Zmievski <andrei@php.net> 
// ...
CACHE_LIMITER_FUNC(private)
{
    ADD_HEADER("Expires: Thu, 19 Nov 1981 08:52:00 GMT");
    CACHE_LIMITER(private_no_expire)(TSRMLS_C);
}