监听器实例jsp编写望大家喜欢

package edu.j2ee.servlet; import javax.servlet.ServletContext; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import javax.servlet.http.HttpSessionAttributeListener; import javax.servlet.http.HttpSessionBindingEvent; import javax.servlet.http.HttpSessionEvent; import javax.servlet.http.HttpSessionListener; import javax.servlet.http.HttpSessionActivationListener; import javax.servlet.http.HttpSessionBindingListener; import java.io.PrintWriter; import java.io.FileOutputStream; public final class MySessionListener implements HttpSessionActivationListener ,HttpSessionAttributeListener, HttpSessionListener,ServletContextListener { ServletContext context; int users=0; //HttpSessionActivationListener public void sessionDidActivate(HttpSessionEvent se) { logout("sessionDidActivate("+se.getSession().getId()+")"); } public void sessionWillPassivate(HttpSessionEvent se) { logout("sessionWillPassivate("+se.getSession().getId()+")"); }//HttpSessionActivationListener //HttpSessionAttributeListener public void attributeAdded(HttpSessionBindingEvent event) { logout("attributeAdded('" + event.getSession().getId() + "', '" + event.getName() + "', '" + event.getValue() + "')"); } public void attributeRemoved(HttpSessionBindingEvent event) { logout("attributeRemoved('" + event.getSession().getId() + "', '" + event.getName() + "', '" + event.getValue() + "')"); } public void attributeReplaced(HttpSessionBindingEvent se) { logout("attributeReplaced('"+se.getSession().getId()+",'"+se.getName()+"','"+se.getValue()+"')"); }//HttpSessionAttributeListener //HttpSessionListener public void sessionCreated(HttpSessionEvent event) { users++; logout("sessionCreated('" + event.getSession().getId() + "'),目前有"+users+"个用户"); context.setAttribute("users",new Integer(users)); } public void sessionDestroyed(HttpSessionEvent event) { users--; logout("sessionDestroyed('" + event.getSession().getId() + "'),目前有"+users+"个用户"); context.setAttribute("users",new Integer(users)); }//HttpSessionListener //ServletContextListener public void contextDestroyed(ServletContextEvent sce) { logout("contextDestroyed()-->ServletContext被销毁"); this.context = null; } public void contextInitialized(ServletContextEvent sce) { this.context = sce.getServletContext(); logout("contextInitialized()-->ServletContext初始化了"); }//ServletContextListener private void logout(String message) { PrintWriter out=null; try { out=new PrintWriter(new FileOutputStream("c:\\session.txt",true)); out.println(new java.util.Date().toLocaleString()+"::Form MySessionListener: " + message); out.close(); } catch(Exception e) { out.close(); e.printStackTrace(); } } }