public  void destroy() 
{
        // NoOp
}

Destroy method for this filter

 public  void doFilter(ServletRequest request,
    ServletResponse response,
    FilterChain chain) throws IOException, ServletException 
{
        if(request.getAttribute(DOFILTER_CALLED)!=null)
        {
            chain.doFilter(request, response);
            return;
        }
        request.setAttribute(DOFILTER_CALLED,"true");
        if (!(response instanceof HttpServletResponse)) {
            chain.doFilter(request, response);
            return;
        }
        HttpServletResponse httpResponse = (HttpServletResponse) response;
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletRequest extendedRequest = httpRequest;
        // For multipart/form-data requests
        if (FileUpload.isMultipartContent(httpRequest)) {
            extendedRequest = new MultipartRequestWrapper(httpRequest, _uploadMaxFileSize, _uploadThresholdSize, _uploadRepositoryPath);
        }
        // Serve resources
        AddResource addResource;
        try
        {
            addResource=AddResourceFactory.getInstance(httpRequest);
            if( addResource.isResourceUri(_servletContext, httpRequest ) ){
                addResource.serveResource(_servletContext, httpRequest, httpResponse);
                return;
            }
        }
        catch(Throwable th)
        {
            log.error("Exception wile retrieving addResource",th);
            throw new ServletException(th);
        }
        try
        {
        	addResource.responseStarted();
	        if (addResource.requiresBuffer())
	        {
		        ExtensionsResponseWrapper extendedResponse = new ExtensionsResponseWrapper((HttpServletResponse) response);
		        // Standard request
		        chain.doFilter(extendedRequest, extendedResponse);
		        extendedResponse.finishResponse();
		        // write the javascript stuff for myfaces and headerInfo, if needed
		        HttpServletResponse servletResponse = (HttpServletResponse)response;
		        // only parse HTML responses
		        if (extendedResponse.getContentType() != null && isValidContentType(extendedResponse.getContentType()))
		        {
		            addResource.parseResponse(extendedRequest, extendedResponse.toString(),
		                    servletResponse);
		            addResource.writeMyFacesJavascriptBeforeBodyEnd(extendedRequest,
		                    servletResponse);
		            if( ! addResource.hasHeaderBeginInfos() ){
		                // writes the response if no header info is needed
		                addResource.writeResponse(extendedRequest, servletResponse);
		                return;
		            }
		            // Some headerInfo has to be added
		            addResource.writeWithFullHeader(extendedRequest, servletResponse);
		            // writes the response
		            addResource.writeResponse(extendedRequest, servletResponse);
		        }
		        else
		        {
		        	byte[] responseArray = extendedResponse.getBytes();
                    if(responseArray.length  > 0)
                    {
 			        	// When not filtering due to not valid content-type, deliver the byte-array instead of a charset-converted string.
 			        	// Otherwise a binary stream gets corrupted.
 			            servletResponse.getOutputStream().write(responseArray);
 		        	}
                }
	        }
	        else
	        {
		        chain.doFilter(extendedRequest, response);
	        }
        }
        finally
        {
        	addResource.responseFinished();        	
        }
}

 public  void init(FilterConfig filterConfig) 
{
              
        String param = filterConfig.getInitParameter("uploadMaxFileSize");
        _uploadMaxFileSize = resolveSize(param, _uploadMaxFileSize);
        param = filterConfig.getInitParameter("uploadThresholdSize");
        _uploadThresholdSize = resolveSize(param, _uploadThresholdSize);
        _uploadRepositoryPath = filterConfig.getInitParameter("uploadRepositoryPath");
        _servletContext = filterConfig.getServletContext();
}

Init method for this filter

 public boolean isValidContentType(String contentType) 
{
        return contentType.startsWith("text/html") ||
                contentType.startsWith("text/xml") ||
                contentType.startsWith("application/xhtml+xml") ||
                contentType.startsWith("application/xml");
}