标签：

        监听器分类

        继续接着监听器的分类进行，来看第二种分类中的第二小类。

       ServletContextAttributeListener实例

       MyServletContextAttributeListener.java源代码：

package com.listener;


import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;
import javax.servlet.annotation.WebListener;


/**
 * Application Lifecycle Listener implementation class MyServletContextAttributeListener
 *
 */
@WebListener
public class MyServletContextAttributeListener implements ServletContextAttributeListener {


    /**
     * Default constructor. 
     */
    public MyServletContextAttributeListener() {
    	
    }


	/**
     * @see ServletContextAttributeListener#attributeAdded(ServletContextAttributeEvent)
     */
    public void attributeAdded(ServletContextAttributeEvent servletContextAttributeEvent)  { 
    	System.out.println("ServletContext_attributeAdded:"+servletContextAttributeEvent.getName());
    }


	/**
     * @see ServletContextAttributeListener#attributeRemoved(ServletContextAttributeEvent)
     */
    public void attributeRemoved(ServletContextAttributeEvent servletContextAttributeEvent)  { 
    	System.out.println("ServletContext_attributeRemoved:"+servletContextAttributeEvent.getName());
    }


	/**
     * @see ServletContextAttributeListener#attributeReplaced(ServletContextAttributeEvent)
     */
    public void attributeReplaced(ServletContextAttributeEvent servletContextAttributeEvent)  { 
    	System.out.println("ServletContext_attributeReplaced:"+servletContextAttributeEvent.getName());
    }
	
}

       HttpSessionAttributeListener实例

       MyHttpSessionAttributeListener.java源代码：

package com.listener;


import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;


/**
 * Application Lifecycle Listener implementation class MyHttpSessionAttributeListener
 *
 */
@WebListener
public class MyHttpSessionAttributeListener implements HttpSessionAttributeListener {


    /**
     * Default constructor. 
     */
    public MyHttpSessionAttributeListener() {
    	
    }


	/**
     * @see HttpSessionAttributeListener#attributeAdded(HttpSessionBindingEvent)
     */
    public void attributeAdded(HttpSessionBindingEvent sessionBindingEvent)  { 
    	System.out.println("HttpSession_attributeAdded:"+sessionBindingEvent.getName());
    }


	/**
     * @see HttpSessionAttributeListener#attributeRemoved(HttpSessionBindingEvent)
     */
    public void attributeRemoved(HttpSessionBindingEvent sessionBindingEvent)  { 
    	System.out.println("HttpSession_attributeRemoved:"+sessionBindingEvent.getName());
    }


	/**
     * @see HttpSessionAttributeListener#attributeReplaced(HttpSessionBindingEvent)
     */
    public void attributeReplaced(HttpSessionBindingEvent sessionBindingEvent)  { 
         System.out.println("HttpSession_attributeReplaced:"+sessionBindingEvent.getName());
    }
	
}

       ServletRequestAttributeListener实例

       ServletRequestAttributeListener.java源代码：

package com.listener;


import javax.servlet.ServletRequestAttributeEvent;
import javax.servlet.ServletRequestAttributeListener;
import javax.servlet.annotation.WebListener;


/**
 * Application Lifecycle Listener implementation class MyServletRequestAttributeListener
 *
 */
@WebListener
public class MyServletRequestAttributeListener implements ServletRequestAttributeListener {


    /**
     * Default constructor. 
     */
    public MyServletRequestAttributeListener() {
        
    }


	/**
     * @see ServletRequestAttributeListener#attributeRemoved(ServletRequestAttributeEvent)
     */
    public void attributeRemoved(ServletRequestAttributeEvent servletRequestAttributeEvent)  { 
    	 System.out.println("ServletRequest_attributeRemoved:"+servletRequestAttributeEvent.getName());
    }


	/**
     * @see ServletRequestAttributeListener#attributeAdded(ServletRequestAttributeEvent)
     */
    public void attributeAdded(ServletRequestAttributeEvent servletRequestAttributeEvent)  { 
    	System.out.println("ServletRequest_attributeAdded:"+servletRequestAttributeEvent.getName());
    }


	/**
     * @see ServletRequestAttributeListener#attributeReplaced(ServletRequestAttributeEvent)
     */
    public void attributeReplaced(ServletRequestAttributeEvent servletRequestAttributeEvent)  { 
    	System.out.println("ServletRequest_attributeReplaced:"+servletRequestAttributeEvent.getName());
    }
	
}

       我们使用的JSP页面包括：

       index.jsp页面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
     <h1>我是JSP页面</h1>
     <hr/>
     <button onclick="location.href=‘<%=request.getContextPath()%>/init.jsp‘;">Init</button>
     <button onclick="location.href=‘<%=request.getContextPath()%>/destory.jsp‘;">Destory</button>
</body>
</html>

       init.jsp页面：

<%@page import="com.domain.Admin"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
      <h1>这是初始化值的页面</h1>
      <hr/>
      
      <%
           request.setAttribute("requestName", "requestValue");
           request.getSession().setAttribute("sessionName", "sessionValue");
           request.getSession().getServletContext().setAttribute("contextName", "contextValue");
      %>
      
      <button onclick="location.href=‘<%=request.getContextPath()%>/init.jsp‘;">Init</button>
      <button onclick="location.href=‘<%=request.getContextPath()%>/destory.jsp‘;">Destory</button>
</body>
</html>

       destory.jsp页面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
      <h1>这是销毁值的页面</h1>
      <hr/>
      
      <%
           request.removeAttribute("requestName");
           request.getSession().removeAttribute("sessionName");
           request.getSession().getServletContext().removeAttribute("contextName");
      %>
      
      <button onclick="location.href=‘<%=request.getContextPath()%>/init.jsp‘;">Init</button>
      <button onclick="location.href=‘<%=request.getContextPath()%>/destory.jsp‘;">Destory</button>
</body>
</html>

       运行结果：

       我们通过访问index页面开始：

       点击init按钮：

       再次点击init按钮：

       点击destory按钮：

       我们来看第三小类。

       session钝化机制

       本质就在于把服务器中不经常使用的Session对象暂时序列化到系统文件系统或者数据库系统中，当使用时反序

列化到内存中，整个过程由服务器自动完成。使用的并不是很多。

       示意图：

       Tomcat中两种session钝化管理器

       session钝化机制由SessionManager管理。

       第一种：

       第二种：

       Servlet规范

       包括两个监听器，都不需要再web.xml中注册。

       HttpSessionBindingListener监听器

       绑定：vlaueBound()方法

       解除绑定：valueUnbound()方法

       HttpSessionActivationListener监听器

       钝化：sessionWillPassivate()方法

       活化：sessionDidActivate()方法

       只提供上述两个监听器的实例源码：

package com.domain;


import java.io.Serializable;


import javax.servlet.http.HttpSessionActivationListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionBindingListener;
import javax.servlet.http.HttpSessionEvent;


public class User implements HttpSessionBindingListener,HttpSessionActivationListener,Serializable {


	private String username;
	private String password;


	public String getUsername() {
		return username;
	}


	public void setUsername(String username) {
		this.username = username;
	}


	public String getPassword() {
		return password;
	}


	public void setPassword(String password) {
		this.password = password;
	}
	
	public void valueBound(HttpSessionBindingEvent httpsessionbindingevent) {
		System.out.println("valueBound Name:"+httpsessionbindingevent.getName());
	}


	public void valueUnbound(HttpSessionBindingEvent httpsessionbindingevent) {
		System.out.println("valueUnbound Name:"+httpsessionbindingevent.getName());
	}


	public void sessionWillPassivate(HttpSessionEvent httpsessionevent) {
		System.out.println("sessionWillPassivate "+httpsessionevent.getSource());
	}
	
	public void sessionDidActivate(HttpSessionEvent httpsessionevent) {
		System.out.println("sessionDidActivate "+httpsessionevent.getSource());
	}


}

Java Web学习(38)：Listener学习(二)

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原文地址：http://blog.csdn.net/erlian1992/article/details/52219885