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WebWork is a Java web-application development framework. It is built specifically with developer productivity and code simplicity in mind, providing robust support for building reusable UI templates, such as form controls, UI themes, internationalization, dynamic form parameter mapping to JavaBeans, robust client and server side validation, and much more.

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package com.opensymphony.webwork.dispatcher;

import com.opensymphony.xwork.ActionContext;
import com.opensymphony.xwork.interceptor.component.ComponentManager;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * 
 * Special filter designed to work with the {@link FilterDispatcher} and allow
 * for easier integration with SiteMesh. Normally, ordering your filters to have
 * SiteMesh go first, and then {@link FilterDispatcher} go second is perfectly fine.
 * However, sometimes you may wish to access WebWork-features, including the
 * value stack, from within your SiteMesh decorators. Because {@link FilterDispatcher}
 * cleans up the {@link ActionContext}, your decorator won't have access to the
 * date you want.
 * 
 * 

 * By adding this filter, the {@link FilterDispatcher} will know to not clean up and
 * instead defer cleanup to this filter. The ordering of the filters should then be:
 * 

 * 

 * this filter
 * SiteMesh filter
 * {@link FilterDispatcher}
 * 
 * 
 *
 * @author Patrick Lightbody
 * @author Pete Matern
 * @see FilterDispatcher
 * @since 2.2
 */
public class ActionContextCleanUp implements Filter {

    private static final Log LOG = LogFactory.getLog(ActionContextCleanUp.class);

    private static final String COUNTER = "__cleanup_counter";

    protected FilterConfig filterConfig;

    public FilterConfig getFilterConfig() {
        return filterConfig;
    }

    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
        DispatcherUtils.initialize(filterConfig.getServletContext());
    }

    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;

        // prepare the request no matter what - this ensures that the proper character encoding
        // is used before invoking the mapper (see WW-9127)
        DispatcherUtils du = DispatcherUtils.getInstance();
        du.prepare(request, response);


        ServletContext servletContext = filterConfig.getServletContext();
        try {
            request = du.wrapRequest(request, servletContext);
        } catch (IOException e) {
            String message = "Could not wrap servlet request with MultipartRequestWrapper!";
            LOG.error(message, e);
            throw new ServletException(message, e);
        }

        try {

            Integer count = (Integer)request.getAttribute(COUNTER);
            if (count == null) {
                count = new Integer(1);
            }
            else {
                count = new Integer(count.intValue()+1);
            }
            request.setAttribute(COUNTER, count);

            chain.doFilter(request, response);
        } finally {

            int counterVal = ((Integer)request.getAttribute(COUNTER)).intValue();
            counterVal -= 1;
            request.setAttribute(COUNTER, new Integer(counterVal));

            cleanUp(request);
        }

    }

    protected static void cleanUp(ServletRequest req) {
        // should we clean up yet
         if (req.getAttribute(COUNTER) != null &&
                 ((Integer)req.getAttribute(COUNTER)).intValue() > 0 ) {
             return;
         }

        // tear down the component manager if it was created
        ComponentManager componentManager = (ComponentManager) req.getAttribute(ComponentManager.COMPONENT_MANAGER_KEY);
        if (componentManager != null) {
            componentManager.dispose();
        }

        // always clean up the thread request, even if an action hasn't been executed
        ActionContext.setContext(null);
    }

    public void destroy() {
    }
}