Authorization filter,2 questions...

Hi guys,
i need your help to solve my question..
i'm developing a jsf application and i've created an authorization
filter...
My filter must checking for each page access if a registered user is
stored in the session,if not redirect to login page. I've a bit
experience on servlet and filter and i've solved this question with
this filter.

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

public class AuthorizationFilter implements Filter {
    /**
     * @uml.property name="config"
     * @uml.associationEnd
     */
    FilterConfig config = null;

    /**
     * @uml.property name="servletContext"
     * @uml.associationEnd
     */
    ServletContext servletContext = null;

    public AuthorizationFilter() {
    }

    public void init(FilterConfig filterConfig) throws ServletException {
        config = filterConfig;
        servletContext = config.getServletContext();
    }

    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        Utils.log(servletContext, "Inside the filter");

        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletResponse httpResponse = (HttpServletResponse) response;
        HttpSession session = httpRequest.getSession();

        String requestPath = httpRequest.getPathInfo();
        Visit visit = (Visit) session.getAttribute("visit");

        if (visit == null) {
            System.out.println("Visit Nullo");
            session.setAttribute("originalTreeId", httpRequest
                    .getPathInfo());
            Utils.log(servletContext, "redirecting to "
                    + httpRequest.getContextPath() + "/faces/Login.jsp");
            httpResponse.sendRedirect(httpRequest.getContextPath()
                    + "/index.jsp");
        }

        else {

            chain.doFilter(request, response);
        }

        Utils.log(servletContext, "Exiting the filter");
    }

    public void destroy() {
    }
}

in my authentication bean,after user has logged in i've

loggedIn=true;

User newUser = new User(loginName, password,teamName, role);
Visit visit = new Visit();
visit.setUser(newUser);
visit.setAuthenticationBean(this);
visit.setLoggedIn(loggedIn);
setVisit(visit);
getApplication().createValueBinding("#{sessionScope.visit}").setValue(facesContext,visit);

to store values into visit object.

and this is my logout function

FacesContext facesContext = getFacesContext();
        Utils.log(facesContext, "Executing AuthenticationBean.logout()");

        HttpSession session = (HttpSession) facesContext.getExternalContext()
                .getSession(false);
        session.removeAttribute("sessionScope.visit");

        if (session != null) {
            session.invalidate();
        }

My 2 questions are:

1) how can i redirect to login page a user that tries to log in with
the same data of a user stored in the session?
2) how can i handling browser closing?I need a listener?
Please help me,i'm trying to learn about it and i need your help.
Thanks