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Session监听器

该接口继承于javax.servlet.http

HttpSessionListener 该接口是监听session对象的创建以及销毁

package 监听器;import javax.servlet.annotation.WebListener;import javax.servlet.http.HttpSessionAttributeListener;import javax.servlet.http.HttpSessionBindingEvent;import javax.servlet.http.HttpSessionEvent;import javax.servlet.http.HttpSessionListener;import javax.websocket.Session;public class HttpSession implements HttpSessionListener,		HttpSessionAttributeListener {
   	public void sessionCreated(HttpSessionEvent arg0) {
   		System.out.println("创建session");	}	public void sessionDestroyed(HttpSessionEvent arg0) {
   		System.out.println("销毁session");	}	public void attributeAdded(HttpSessionBindingEvent arg0) {
   		System.out.println("给session添加属性：");		System.out.println("session对象名"+arg0.getName());//输出session对象的属性		System.out.println("session对象值"+arg0.getValue());//输出session对象的值	}	public void attributeRemoved(HttpSessionBindingEvent arg0) {
   		System.out.println("删除值");		System.out.println("(删除后)对象名："+arg0.getName());		System.out.println("session的值(删除后):"+arg0.getSession().getAttribute(arg0.getName()));	}	public void attributeReplaced(HttpSessionBindingEvent arg0) {
   		System.out.println("session对象名(修改后):"+arg0.getName());				System.out.println("session的值(修改后):"+arg0.getSession().getAttribute(arg0.getName()));	}}

2.0 测试的servlet，对session对象的创建以及属性的修改

package 监听器;import java.io.IOException;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;@WebServlet("/testHttpSession")public class testHttpSession extends HttpServlet {
   		protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   				HttpSession session=request.getSession();		//对session对象添加值，attributeAdded()方法		session.setAttribute("name", "ysdqh123");		//对session值进行修改，对应的是attributeReplaced()方法		session.setAttribute("name", "ysdqh456");		session.removeAttribute("name");	//删除值	}		protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   		doGet(request, response);	}}

在web.xml配置文件当中添加此段代码，配置监听器代码

       
    
     监听器2
        
    
     监听器.HttpSession
      
   

Context监听器

ServletContextListener

ServletContextAttributeListener

在此下代码中，俩个接口，以及其共5个方法，皆已实现，代码如下：

package 监听器;import javax.servlet.ServletContextAttributeEvent;import javax.servlet.ServletContextAttributeListener;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import javax.servlet.annotation.WebListener;public class ServletContext implements ServletContextAttributeListener, ServletContextListener {
           public void attributeAdded(ServletContextAttributeEvent arg0) {
       	System.out.println("属性添加方法");    	System.out.println("对象名、即属性名 ："+arg0.getName());    	System.out.println("对象的值 ："+arg0.getServletContext().getAttribute(arg0.getName()));    }	    public void attributeRemoved(ServletContextAttributeEvent arg0) {
       	System.out.println("属性删除方法");    	System.out.println("（删除后）属性名："+arg0.getName());    	System.out.println("（删除后） 值："+arg0.getServletContext().getAttribute(arg0.getName()));    }		public void contextDestroyed(ServletContextEvent arg0) {
   		System.out.println("监听器销毁方法");	}    public void attributeReplaced(ServletContextAttributeEvent arg0) {
       	System.out.println("属性更新方法");    	System.out.println("（修改后）属性名 :"+arg0.getName());    	System.out.println("（修改后）值："+arg0.getServletContext().getAttribute(arg0.getName()));    }	    public void contextInitialized(ServletContextEvent arg0) {
       	System.out.println("监听器创建方法");    }	}

测试的servlet

package 监听器;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/testcontext")public class testcontext extends HttpServlet {
   		protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   		this.getServletContext().setAttribute("name", "yueyueniao1");		this.getServletContext().setAttribute("name", "yueyueniao2");		this.getServletContext().removeAttribute("name");	}	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   		doGet(request, response);	}}

在web.xml配置文件当中添加此段代码

       
    
     监听器1
        
    
     监听器.ServletContext
      
   

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