sessioncleanupinterceptor.java

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package net.java.workeffort.webapp.support;

import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

/**
 * Cleans up form objects in the session whenever user navigates from the main
 * menu
 * @author Antony Joseph
 */
public class SessionCleanupInterceptor extends HandlerInterceptorAdapter {
    protected static final Log logger = LogFactory
            .getLog(SessionCleanupInterceptor.class);

    public boolean preHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {
        if (logger.isInfoEnabled())
        logger.info("preHandle() invoked");
        
        // The user is navigating from the Menu. cleanup the session attributes
        // (attributes which start with 'FORM.' or end with 'FormHelper'
        if (request.getParameter("fromMenu") != null) {
            Set namesToBeDeleted = new HashSet();
            Enumeration names = request.getSession().getAttributeNames();
            while (names.hasMoreElements()) {
                String name = (String) names.nextElement();
                if (name.startsWith("FORM.") || name.indexOf("FormHelper") > 0) {
                    namesToBeDeleted.add(name);
                }
            }
            Iterator it = namesToBeDeleted.iterator();
            while (it.hasNext()) {
                request.getSession().removeAttribute((String) it.next());
            }
        }
        
        return true;
    }

}