public  void destroy() 
{
        this.attribute = null;
        this.filterConfig = null;
}

Take this filter out of service.

 public  void doFilter(ServletRequest request,
    ServletResponse response,
    FilterChain chain) throws IOException, ServletException 
{
	// Store ourselves as a request attribute (if requested)
	if (attribute != null)
	    request.setAttribute(attribute, this);
	// Time and log the subsequent processing
	long startTime = System.currentTimeMillis();
        chain.doFilter(request, response);
	long stopTime = System.currentTimeMillis();
	filterConfig.getServletContext().log
	    (this.toString() + ": " + (stopTime - startTime) +
	     " milliseconds");
}

Time the processing that is performed by all subsequent filters in the current filter stack, including the ultimately invoked servlet.

 public  void init(FilterConfig filterConfig) throws ServletException 
{
	this.filterConfig = filterConfig;
        this.attribute = filterConfig.getInitParameter("attribute");
}

Place this filter into service.

 public String toString() 
{
	if (filterConfig == null)
	    return ("InvokerFilter()");
	StringBuffer sb = new StringBuffer("InvokerFilter(");
	sb.append(filterConfig);
	sb.append(")");
	return (sb.toString());
}

Return a String representation of this object.