It would be nice to add some improvements to the CacheFilter class in order to make it easier to have a sub-class.

Another good point would be to have a method called to decide whether a cache entry sould be used or not.

/**
     * useCache is a method allowing subclass to decide if the use
     * of the cache is requested or not.
     *
     * @param request The HTTP servlet request
     * @param response The HTTP servlet response
     * @param key The cache key used to access the cache
     * @param cache The cache object
     * @return Returns a boolean indicating if the caching is requested or not.
     */
    protected boolean useCache(HttpServletRequest request,
                               HttpServletResponse response,
                               String key,
                               Cache cache) {
        boolean useIt = true ;

if (log.isDebugEnabled()) {
            log.debug("<cache>: the cache " + ((useIt) ? "will" : "will not") + " be used.");
        }
        return useIt ;
    }