public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;
        ServletContext servletContext = getServletContext();
 
        String timerKey = "FilterDispatcher_doFilter: ";
        try {
            UtilTimerStack.push(timerKey);
            request = prepareDispatcherAndWrapRequest(request, response);
            ActionMapping mapping;
            try {
                mapping = actionMapper.getMapping(request, dispatcher.getConfigurationManager());
            } catch (Exception ex) {
                LOG.error("error getting ActionMapping", ex);
                dispatcher.sendError(request, response, servletContext, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, ex);
                return;
            }
 
            if (mapping == null) {
                String resourcePath = RequestUtils.getServletPath(request);
 
                if ("".equals(resourcePath) && null != request.getPathInfo()) {
                    resourcePath = request.getPathInfo();
                }
 
                if (serveStatic && resourcePath.startsWith("/struts")) {
                    findStaticResource(resourcePath, findAndCheckResources(resourcePath), request, response);
                } else {
                    chain.doFilter(request, response);//激活下一个过滤器
                }
                // The framework did its job here
                return;
            }
            dispatcher.serviceAction(request, response, servletContext, mapping);
 
        } finally {
            try {
                ActionContextCleanUp.cleanUp(req);
            } finally {
                UtilTimerStack.pop(timerKey);
            }
        }
    }