javaweb . 页面登出 操作

对于 监听器的使用

 

package com.itstaredu.bookstore.listener;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
import javax.servlet.http.HttpSessionBindingEvent;

public class MySessionListener implements ServletContextListener,
        HttpSessionListener, HttpSessionAttributeListener {

    // Public constructor is required by servlet spec
    public MySessionListener() {
    }

    // -------------------------------------------------------
    // ServletContextListener implementation
    // -------------------------------------------------------
    @Override
    public void contextInitialized(ServletContextEvent sce) {
      /* This method is called when the servlet context is
         initialized(when the Web application is deployed). 
         You can initialize servlet context related data here.
      */
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
      /* This method is invoked when the Servlet Context 
         (the Web application) is undeployed or 
         Application Server shuts down.
      */
    }

    // -------------------------------------------------------
    // HttpSessionListener implementation
    // -------------------------------------------------------
    @Override
    public void sessionCreated(HttpSessionEvent se) {
        /* Session is created. */
        ServletContext sc = se.getSession().getServletContext();
        Object count = sc.getAttribute("count");
        if (count == null) {
            sc.setAttribute("count", 1);
        } else {
            sc.setAttribute("count", (Integer) count + 1);
        }
    }

    @Override
    public void sessionDestroyed(HttpSessionEvent se) {
        /* Session is destroyed. */
        ServletContext sc = se.getSession().getServletContext();
        sc.setAttribute("count", (Integer) (sc.getAttribute("count")) - 1);
    }

    // -------------------------------------------------------
    // HttpSessionAttributeListener implementation
    // -------------------------------------------------------

    @Override
    public void attributeAdded(HttpSessionBindingEvent sbe) {
      /* This method is called when an attribute 
         is added to a session.
      */
    }

    @Override
    public void attributeRemoved(HttpSessionBindingEvent sbe) {
      /* This method is called when an attribute
         is removed from a session.
      */
    }

    @Override
    public void attributeReplaced(HttpSessionBindingEvent sbe) {
      /* This method is invoked when an attibute
         is replaced in a session.
      */
    }
}

　　

跳转到登出页面时候，无论是分发 或是 重定向，服务器会判定该用户的再一次访问，所以把对session的销毁放在最后面

package com.itstaredu.bookstore.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

/**
 * @author 
 */
public class LogoutServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();
        // go to login page
        System.out.println("logout");
        System.out.println(session.getServletContext().getAttribute("count"));
        request.getRequestDispatcher("/login.jsp").forward(request, response);
        session.invalidate();
    }
}