浏览器不缓存生成的图像 [英] Browser not caching generated images

问题描述

似乎在某些测试中，Firefox不会缓存动态生成（或从缓存服务器端加载）的图像。

It seems that during some tests, Firefox will not cache images that are dynamically generated (or loaded from the cache serverside).

我尝试使用标头启用缓存：

I tried enabling caching using headers:

$expires = 60*60*24*14;
header("Pragma: public");
header("Cache-Control: maxage=".$expires);
header('Expires: ' . gmdate('D, d M Y H:i:s', time()+$expires) . ' GMT');

但无济于事。我仍然得到200 OK而不是304 Not Modified。

But to no avail. I still get a "200 OK" instead of "304 Not Modified".

使用Stackoverflow上的搜索寻求答案，我发现有人暗示他们宁愿直接将浏览器重新定位到图像。

Seeking an answer using the search on Stackoverflow, i discovered a hint by someone that they would rather relocate the browser to the image directly.

喜欢：

header("Location: /img/generated/whatever.png");

我不喜欢这种方法，因为它会导致两个请求。

I don't like the approach because it causes two requests.

任何人都可以帮助我，让我知道如何让浏览器缓存这些文件？

Could anyone help me out and let me know how i could just get the browser to cache these files?

请求URL未更改，并且不包含任何种子或时间戳。

The Request URL is not changing and it does not contain any seeds or timestamps.

推荐答案

此处缺少的是您的响应标头中的最后修改标头。 ex Last-Modified：Wed，15 Feb 2012 10:07:48 GMT 。您可以通过在标题中使用此行来解决此问题。

What you are missing here is last modified header in your reponse header. ex Last-Modified:Wed, 15 Feb 2012 10:07:48 GMT. you can solve this by using this line with your headers.

    header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . ' GMT');

你之所以应该拥有这个，是因为浏览器使用最后一个modidfied标头来比较文件是不是修改后无需重新下载文件。 ：

The reason why you should have this because the browser uses last modidfied header to compare if the file is not modified thus no need to re download the file. :

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