如何使用控制缓存标头?

问题描述

我为 Google chrome 下载了 Google 速度跟踪器，以查看我的网站在性能方面的表现如何，它告诉我需要为某些文件启用缓存，例如我的 style.css、图像等.

I downloaded Google speed tracer for Google chrome to see how my site does performance wise and it tells me I need to enable caching for certain files like my style.css, images, etc.

我读过下面的 php 代码应该告诉浏览器缓存 html 内容.我写了一个快速的 php 页面，上面有几张图片，并将下面的代码贴在顶部(在发送标题之前)以测试它是如何工作的.

I've read that the below php code should tell browsers to cache html content. I wrote a quick php page with a couple of images on it and stuck the below code at the top (before the headers are sent) to test to see how it worked.

Header("Cache-Control: public, max-age=3600, must-revalidate");

当我回到速度追踪器的分析时，它说...

When I go back to speed tracer's analysis it says...

总结来自缓存:false

请求标头Pragma:没有缓存缓存控制:max-age=0

Request Headers Pragma: no cache Cache-Control: max-age=0

但在响应标头下...Cache-Control: public, max-age=3600, must-revalidate (正是我指定的)

but under Response Headers... Cache-Control: public, max-age=3600, must-revalidate (exactly what I specified)

我有点困惑，这是怎么回事……?当它说 from cache: false 是否意味着来自服务器缓存而不是客户端缓存?

I'm a little confused, what's going on...? When it says from cache: false does that mean from the server cache and not the client's cache?

推荐答案

关键是must-revalidate:这意味着客户端询问服务器文件是否已更改.如果您不处理这种情况，浏览器将获取一个新副本.

The key is must-revalidate: This means, that the client is asking the server if the file has changed. If you don’t handle this case, the browser will fetch a new copy.

阅读 Mark Nottingham 的出色缓存教程 了解更多信息.作为 PHP 实现的示例，您可以使用 我的代码.

Read Mark Nottingham’s fantastic Caching Tutorial for more information. As an example for a PHP implementation you may use my code.

查看 $_SERVER['HTTP_IF_NONE_MATCH'] 和 $_SERVER['HTTP_IF_MODIFIED_SINCE'] 以验证客户端.请注意，这两个标头都可能包含恶意代码.;)

Look into $_SERVER['HTTP_IF_NONE_MATCH']and $_SERVER['HTTP_IF_MODIFIED_SINCE'] for validating clients. And be aware that both headers may contain malicious code. ;)

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