public void init(FilterConfig filterConfig) throws ServletException {
   super.init(filterConfig);
   String excludedExtensionsParam = filterConfig.getInitParameter("excludedExtensions");
   if (excludedExtensionsParam != null) {
     StringTokenizer tokenizer = new StringTokenizer(excludedExtensionsParam, ",", false);
     while (tokenizer.hasMoreTokens()) {
       excludedExtensions.add(tokenizer.nextToken().trim());
     }
   }
 }
 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
     throws IOException, ServletException {
   HttpServletRequest httpRequest = (HttpServletRequest) request;
   // do not use the filter if this is a server-side include, JSP, or image file
   if (httpRequest.getAttribute(INCLUDE_REQUEST_URI_ATTRIBUTE) == null
       && (!isExcludedFileExtension(httpRequest.getPathInfo()))) {
     super.doFilter(request, response, chain);
   } else {
     chain.doFilter(request, response);
   }
 }