public function getCachedFile($cacheKey) {

        // Get directory and filename
        list($directory, $filename) = $this->getDirectoryAndFilenameFromKey($cacheKey);

        if (file_exists($directory . "/" . $filename) && !is_dir($directory . "/" . $filename)) {
            return file_get_contents($directory . "/" . $filename);
        }

        return null;


    }