PHP下利用header()函数设置浏览器缓存的代码_php技巧
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 |
// Connect to the database:
$dbc = @mysqli_connect ('localhost', 'username', 'password', 'test') OR die ('
Could not connect to the database!

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