1.作用：监听Session创建或销毁，即生命周期监听

2.相关方法：

//void sessionCreated(HttpSessionEvent se):创建session时调用
//void sessionDestroyed(HttpSessionEvent se):销毁sessio时调用

3.使用场景：

和前面的ServletContextListener等一样，可以用于监控用户上线和离线

4.代码

HttpSessionListener监听器

package com.listener;import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;public class hspHttpSessionListener implements HttpSessionListener {@Overridepublic void sessionCreated(HttpSessionEvent se) {HttpSession session = se.getSession();//当session被创建时，设置一个统一的生命周期session.setMaxInactiveInterval(30);System.out.println("hspHttpSessionListener 监听到session创建="+session.getId());}@Overridepublic void sessionDestroyed(HttpSessionEvent se) {HttpSession session = se.getSession();System.out.println("hspHttpSessionListener 监听到session销毁="+session.getId());}
}

实现类

package com.servlet;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;@WebServlet(name = "HiServlet",urlPatterns = "/HiServlet")
public class HiServlet extends HttpServlet {@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取session对象HttpSession session = request.getSession();}@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}
}

HttpSessionAttributeListener监听器

1.作用：监听Session属性的变化,使用少

2.相关方法：

//void attributeAdded(ServletRequestAttritubeEvent srae):添加属性时
//void attributeReplaced(ServletRequestAttritubeEvent srae)：替换属性时
//void attributeRemoved(ServletRequestAttritubeEvent srae):移除属性时

3.代码

监听器

package com.listener;import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;public class hspHttpServletAttributeListener implements HttpSessionAttributeListener {@Overridepublic void attributeAdded(HttpSessionBindingEvent se) {System.out.println("hspHttpServletAttributeListener 监听到session添加属性="+se.getName()+"="+se.getValue());}@Overridepublic void attributeRemoved(HttpSessionBindingEvent se) {System.out.println("hspHttpServletAttributeListener 监听到session删除属性="+se.getName());}@Overridepublic void attributeReplaced(HttpSessionBindingEvent se) {System.out.println("hspHttpServletAttributeListener 监听到session修改属性="+se.getName()+"="+se.getValue());}
}

实现类

package com.servlet;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;@WebServlet(name = "HiServlet",urlPatterns = "/HiServlet")
public class HiServlet extends HttpServlet {@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取session对象HttpSession session = request.getSession();//添加数据session.setAttribute("age",100);session.setAttribute("age",40);session.removeAttribute("age");System.out.println("HiServlet操作完毕...");}@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}
}