Java教程
JavaWeb Listener 监听器(第十一次作业)
1.创建监听器:
在chepter11创建一个chapter11.listener包,编写一个mylistener类,用来实现若干个监听器接口
mylistener.java如下：
package chapter11.listener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
/**
* Application Lifecycle Listener implementation class mylistener
*
*/
@WebListener
public class mylistener implements ServletContextListener, HttpSessionListener, ServletRequestListener {
/**
* Default constructor.
*/
/**
* @see HttpSessionListener#sessionCreated(HttpSessionEvent)
*/
public void sessionCreated(HttpSessionEvent arg0) {
// TODO Auto-generated method stub
System.out.println("servletsession被创建了");
}
/**
* @see ServletRequestListener#requestDestroyed(ServletRequestEvent)
*/
public void requestDestroyed(ServletRequestEvent arg0) {
// TODO Auto-generated method stub
System.out.println("servletrequest被销毁了");
}
/**
* @see ServletRequestListener#requestInitialized(ServletRequestEvent)
*/
public void requestInitialized(ServletRequestEvent arg0) {
// TODO Auto-generated method stub
System.out.println("servletrequest被创建了");
}
/**
* @see HttpSessionListener#sessionDestroyed(HttpSessionEvent)
*/
public void sessionDestroyed(HttpSessionEvent arg0) {
// TODO Auto-generated method stub
System.out.println("servletsession被销毁了");
}
/**
* @see ServletContextListener#contextDestroyed(ServletContextEvent)
*/
public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub
System.out.println("servletcontext被销毁了");
}
/**
* @see ServletContextListener#contextInitialized(ServletContextEvent)
*/
public void contextInitialized(ServletContextEvent arg0) {
// TODO Auto-generated method stub
System.out.println("servletcontext被创建了");
}
}
2.添加监听信息类,在web.xml文件中添加 mylistener事件监听器信息;
<listener>
<listener-class>
chapter11.listener.mylistener
</listener-class>
</listener>
运行mylistener.java结果:
3.设置监听超时信息;
在web.xml文件中设置session的超时时间为2min
<session-config>
<session-timeout>2</session-timeout>
</session-config>
运行结果:
2.创建测试页面:
在chepter11中新建一个testattribute.jsp用来观察属性事件监听器的作用
<?xml version="1.0" encoding="UTF-8" ?>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Insert title here</title>
</head>
<body>
<h3>这是个测试对象属性信息监听器的页面</h3>
<%
getServletContext().setAttribute("username", "itcast");
getServletContext().setAttribute("username", "itheima");
getServletContext().removeAttribute("username");
session.setAttribute("username", "itcast");
session.setAttribute("username", "itheima");
session.removeAttribute("username");
request.setAttribute("username", "itcast");
request.setAttribute("username", "itheima");
request.removeAttribute("username");
%>
</body>
</html>
创建监听器,在chapter11.listener里创建myattributelistener.java的监听类;
package chapter11.listener;
import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;
import javax.servlet.ServletRequestAttributeEvent;
import javax.servlet.ServletRequestAttributeListener;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
/**
* Application Lifecycle Listener implementation class myattributelistener
*
*/
@WebListener
public class myattributelistener implements ServletContextAttributeListener, HttpSessionAttributeListener, ServletRequestAttributeListener {
/**
* Default constructor.
*/
public myattributelistener() {
// TODO Auto-generated constructor stub
}
/**
* @see ServletContextAttributeListener#attributeAdded(ServletContextAttributeEvent)
*/
public void attributeAdded(ServletContextAttributeEvent sae) {
// TODO Auto-generated method stub
String name = sae.getName();
System.out.println("servletcontext添加属性:"+ name + "="+sae.getServletContext().getAttribute(name));
}
/**
* @see ServletContextAttributeListener#attributeRemoved(ServletContextAttributeEvent)
*/
public void attributeRemoved(ServletContextAttributeEvent sae) {
// TODO Auto-generated method stub
String name = sae.getName();
System.out.println("servletcontext移除属性:"+name);
}
/**
* @see ServletRequestAttributeListener#attributeRemoved(ServletRequestAttributeEvent)
*/
public void attributeRemoved(ServletRequestAttributeEvent sra) {
// TODO Auto-generated method stub
String name = sra.getName();
System.out.println("servletrequest移除属性"+name);
}
/**
* @see ServletRequestAttributeListener#attributeAdded(ServletRequestAttributeEvent)
*/
public void attributeAdded(ServletRequestAttributeEvent sra) {
// TODO Auto-generated method stub
String name = sra.getName();
System.out.println("servletrequest添加属性:"+ name + "="+sra.getServletRequest().getAttribute(name));
}
/**
* @see ServletRequestAttributeListener#attributeReplaced(ServletRequestAttributeEvent)
*/
public void attributeReplaced(ServletRequestAttributeEvent sra) {
// TODO Auto-generated method stub
String name = sra.getName();
System.out.println("servletrequest替换属性:"+ name + "="+sra.getServletRequest().getAttribute(name));
}
/**
* @see HttpSessionAttributeListener#attributeAdded(HttpSessionBindingEvent)
*/
public void attributeAdded(HttpSessionBindingEvent hbe) {
// TODO Auto-generated method stub
String name = hbe.getName();
System.out.println("httpsession添加属性:"+ name + "="+hbe.getSession().getAttribute(name));
}
/**
* @see HttpSessionAttributeListener#attributeRemoved(HttpSessionBindingEvent)
*/
public void attributeRemoved(HttpSessionBindingEvent hbe) {
// TODO Auto-generated method stub
String name = hbe.getName();
System.out.println("httpsession移除属性:"+name);
}
/**
* @see HttpSessionAttributeListener#attributeReplaced(HttpSessionBindingEvent)
*/
public void attributeReplaced(HttpSessionBindingEvent hbe) {
// TODO Auto-generated method stub
String name = hbe.getName();
System.out.println("httpsession替换属性:"+ name + "="+hbe.getSession().getAttribute(name));
}
/**
* @see ServletContextAttributeListener#attributeReplaced(ServletContextAttributeEvent)
*/
public void attributeReplaced(ServletContextAttributeEvent sea) {
// TODO Auto-generated method stub
String name = sea.getName();
System.out.println("servletcontext替换属性:"+ name + "="+sea.getServletContext().getAttribute(name));
}
}添加监听信息,在web.xml文件中输入一下内容:
<listener>
<listener-class>
chapter11.listener.myattributelistener
</listener-class>
</listener>
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