如何停止在Apache服务器上缓存图像

Question

I have been looking everywhere to solve the caching problem on a part of my website that requires the most current version of a file. This file is a background image that can be uploaded by the user. It uses a form to upload an image to a certain folder on the server. Everytime the user's page is loaded the php script echos CSS into the head tag of the page.

I know about tricks like appending a random string or time stamp to the end of the source file in the src attribute of an image. However, in my case there is no img tag. The background image is applied to a wrapper div via css:

#wrapper{
   background-image:url('dir/imagename.jpg');
}

In terms of stopping the browser caching I have tried the following:

 <meta Http-Equiv="Cache-Control" Content="no-cache"> <meta Http-Equiv="Pragma" Content="no-cache"> <meta Http-Equiv="Expires" Content="0"> <meta Http-Equiv="Pragma-directive: no-cache"> <meta Http-Equiv="Cache-directive: no-cache"> 

That code has been added in to the head tag of the page.

I have also tried this with php:

 header("Expires: Tue, 01 Jan 2000 00:00:00 GMT"); header("Last-Modified: " . gmdate("D, d MYH:i:s") . " GMT"); header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0"); header("Cache-Control: post-check=0, pre-check=0", false); header("Pragma: no-cache"); 

Even after all these changes, I have to refresh the page at least a dozen times for the image to update. When downloading the image via ftp client or built in file manager I can see that the image has been updated instantly. So, I conclude that the browser (Google Chrome) is caching these images and I can't seem to interrupt or prevent this process.

Any ideas?

Answer 1

You need to "uncache" the static assets like images, CSS and JavaScript. I don't know how you are sending the headers for those, coz they don't work that way. Using .htaccess add this rule to tell browsers not to cache .jpg , .jpeg , .png , .gif :

<FilesMatch "\.(jpg|jpeg|png|gif)$">
Header set Expires "Tue, 01 Jan 2000 00:00:00 GMT"
</FilesMatch>