Jsp中的Application使用
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JSP中Application有两种含义，第一，表示四种属性范围中的“服务器范围”。第二，表示一个内置对象（JSP有九大内置对象）。综合起来也就是说，它是这么一个对象，当服务器打开时它就创建，服务器关闭时，它就消失。
范例：监视器实现，
ServletContextAttribute.jsp：
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<html>
<head>
<title>My JSP 'ServletContextAttribute.jsp' starting page</title>
</head>
<body>
<%
application.setAttribute("name","Hello") ;
application.removeAttribute("name") ;
%>
</body>
</html>
ServletContextListenerDemo.java：
package org.lxh.listener.app;
import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
public class ServletContextListenerDemo implements
ServletContextAttributeListener, ServletContextListener {
public void attributeAdded(ServletContextAttributeEvent arg0) {
System.out.println("** 增加属性：" + arg0.getName() + " --> " + arg0.getValue()) ;
}
public void attributeRemoved(ServletContextAttributeEvent arg0) {
System.out.println("** 删除属性：" + arg0.getName() + " --> " + arg0.getValue()) ;
}
public void attributeReplaced(ServletContextAttributeEvent arg0) {
System.out.println("** 替换属性：" + arg0.getName() + " --> " + arg0.getValue()) ;
}
public void contextDestroyed(ServletContextEvent arg0) {
System.out.println("** 容器销毁：" + arg0.getServletContext().getRealPath("/"));
}
public void contextInitialized(ServletContextEvent arg0) {
System.out.println("** 容器初始化：" + arg0.getServletContext().getRealPath("/"));
}
}
范例：监视器实现，
ServletContextAttribute.jsp：
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<html>
<head>
<title>My JSP 'ServletContextAttribute.jsp' starting page</title>
</head>
<body>
<%
application.setAttribute("name","Hello") ;
application.removeAttribute("name") ;
%>
</body>
</html>
ServletContextListenerDemo.java：
package org.lxh.listener.app;
import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
public class ServletContextListenerDemo implements
ServletContextAttributeListener, ServletContextListener {
public void attributeAdded(ServletContextAttributeEvent arg0) {
System.out.println("** 增加属性：" + arg0.getName() + " --> " + arg0.getValue()) ;
}
public void attributeRemoved(ServletContextAttributeEvent arg0) {
System.out.println("** 删除属性：" + arg0.getName() + " --> " + arg0.getValue()) ;
}
public void attributeReplaced(ServletContextAttributeEvent arg0) {
System.out.println("** 替换属性：" + arg0.getName() + " --> " + arg0.getValue()) ;
}
public void contextDestroyed(ServletContextEvent arg0) {
System.out.println("** 容器销毁：" + arg0.getServletContext().getRealPath("/"));
}
public void contextInitialized(ServletContextEvent arg0) {
System.out.println("** 容器初始化：" + arg0.getServletContext().getRealPath("/"));
}
}
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