Home Backend Development PHP Tutorial PHP下利用header()函数设置浏览器缓存的代码_php技巧

PHP下利用header()函数设置浏览器缓存的代码_php技巧

May 17, 2016 am 09:23 AM
header php browser cache

这涉及到4种头标类型:

Last-Modified(最后修改时间);
Expires(有效期限);
Pragma(编译指示);
Cache-Control(缓存控制);
  前三个头标属于HTTP1.0标准。头标Last-Modified使用UTC日期时间值。如果缓存系统发现Last-Modified值比页面缓存版本的更接
近当前时间,他就知道应该使用来自服务器的新版本。

  Expires 表明了缓存版本何时应该过期(格林威治标准时间)。把它设置为一个以前的时间就会强制使用服务器上的页面。

  Pragma生命了页面数据应该如何被处理。可以这样避免对页面进行缓存:

  header("Pragma:no-cache");

  Cache-Co0ntrol 头标是在HTTP1.1里添加的,能够实现更细致的控制(还应该继续使用HTTP1.0头标)。Cache-Control的设置有
很多,如下表:

指令 含义
public 可以在任何地方缓存
private 只能被浏览器缓存
no-cache 不能在任何地方缓存
must-revalidate 缓存必须检查更新版本
proxy-revalidate 代理缓存必须检查更新版本
max-age 内容能够被缓存的时期,以秒表示
s-maxage 覆盖共享缓存的max-age设置
下面实例利用header()设置浏览器的缓存:
复制代码 代码如下:

// Connect to the database:
$dbc = @mysqli_connect ('localhost', 'username', 'password', 'test') OR die ('

Could not connect to the database!

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