title: Allow caching with Spring MVC mvc:resources tag
body: <p>I've configured the Spring 3 MVC Dispatcher servlet at the root of my webapp, and using mvc:resources for serving static content as described in the docs:
  <a href="http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-static-resources" rel="noreferrer">http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-static-resources</a></p>
  
  <p>Google's Chrome browser Audit tells me that the resources are explicitly non-cacheable.  Here are the headers the same browser says is sent with the response:</p>
  
  <pre><code>Cache-Control:max-age=31556926, must-revalidate
  Content-Length:1022
  Content-Type:image/png
  Date:Tue, 11 Jan 2011 00:20:07 GMT
  Expires:Wed, 11 Jan 2012 06:08:53 GMT
  Last-Modified:Mon, 29 Nov 2010 19:53:48 GMT
  </code></pre>
  
  <p>So, what do I need in order to make the resource cacheable?</p>