javaweb监听器和juery技术

监听servlet创建

package com.hspedu.listener;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/**
 * 老韩解读
 * 1. 当一个类实现了 ServletContextListener
 * 2. 该类就是一个监听器
 * 3. 该类可以监听的事件 由该类实现的监听接口决定 ，比如 实现ServletContextListener
 *    , 则该类就可以监听 ServletContext对象的创建和销毁, 以此类推
 * 4. HspServletContextListener 就是一个监听者
 * 5. 当web应用启动时，就会产生 ServletContextEvent 事件, 会调用监听器的对应事件处理方法
 *    contextInitialized, 同时会传递 事件对象
 * 6. 程序员可以通过 ServletContextEvent 事件对象，来获取需要的信息, 然后再进行业务处理
 * 7. tomcat怎么知道这个监听器存在 ? 因为我们需要在web.xml中配置
 */
public class HspServletContextListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        ServletContext servletContext = servletContextEvent.getServletContext();
        System.out.println("HspServletContextListener 监听到 " +
                servletContext + " 被创建..");
        //如果我们获取到ServletContext 对象..进行业务处理

    }

    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {
        ServletContext servletContext = servletContextEvent.getServletContext();
        System.out.println("HspServletContextListener 监听到 " +
                servletContext + " 被销毁..");

        //比如可以对servletContext 数据进行处理， 或者日志的管理...
        System.out.println("进行处理工作.....");
    }
}

HspHttpSessionListener 监听到 session销毁= FAEC215D4C92B5325848CF7438FC7138
用户id=FAEC215D4C92B5325848CF7438FC7138 离线
HspHttpSessionListener 监听到 session销毁= 2785B79C0D9A36C33CA215EA5C23D254
用户id=2785B79C0D9A36C33CA215EA5C23D254 离线

监听文本属性的变化

package com.hspedu.listener;

import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;

public class HspServletContextAttributeListener implements ServletContextAttributeListener {
    @Override
    public void attributeAdded(ServletContextAttributeEvent servletContextAttributeEvent) {

        System.out.println("HspServletContextAttributeListener 监听到添加属性.."
                + servletContextAttributeEvent.getName() + "=" + servletContextAttributeEvent.getValue() );
    }

    @Override
    public void attributeRemoved(ServletContextAttributeEvent servletContextAttributeEvent) {

        System.out.println("HspServletContextAttributeListener 监听到删除属性.."
                + servletContextAttributeEvent.getName() + "=" + servletContextAttributeEvent.getValue() );
    }

    @Override
    public void attributeReplaced(ServletContextAttributeEvent servletContextAttributeEvent) {

        System.out.println("HspServletContextAttributeListener 监听到修改属性.."
                + servletContextAttributeEvent.getName() + "=" + servletContextAttributeEvent.getValue() );

    }
}

package com.hspedu.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

public class HiServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        
        //给servletContext 对象操作属性
        ServletContext servletContext = request.getServletContext();
        servletContext.setAttribute("name", "韩顺平教育");
        servletContext.setAttribute("name", "老韩教育");
        servletContext.removeAttribute("name");

        //获取session对象
        //Filter

        HttpSession session = request.getSession();
        session.setAttribute("age", 100);
        session.setAttribute("age", 400);
        session.removeAttribute("age");

        System.out.println("HiServlet 处理完毕....");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

HspHttpSessionListener 监听到 session销毁= FAEC215D4C92B5325848CF7438FC7138
用户id=FAEC215D4C92B5325848CF7438FC7138 离线
HspHttpSessionListener 监听到 session销毁= 2785B79C0D9A36C33CA215EA5C23D254
用户id=2785B79C0D9A36C33CA215EA5C23D254 离线
HspRequestListener 监听到 request对象创建
记录访问日志....
访问IP= 127.0.0.1
访问的资源= http://localhost:8080/filter/hi
HspServletContextAttributeListener 监听到添加属性..name=韩顺平教育
HspServletContextAttributeListener 监听到修改属性..name=韩顺平教育
HspServletContextAttributeListener 监听到删除属性..name=老韩教育
HspHttpSessionListener 监听到 session创建= A8714B2384A7FF7505EA20A456952DAC
用户id=A8714B2384A7FF7505EA20A456952DAC 上线
HspHttpSessionAttributeListener 监听到session添加属性age=100
HspHttpSessionAttributeListener 监听到session修改属性age=100
HspHttpSessionAttributeListener 监听到session删除属性age
HiServlet 处理完毕....
HspRequestListener 监听到 request对象被销毁

监听session创建

package com.hspedu.listener;

import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

public class HspHttpSessionListener implements HttpSessionListener {
    @Override
    public void sessionCreated(HttpSessionEvent httpSessionEvent) {
        HttpSession session = httpSessionEvent.getSession();
        //当session创建时，我们给它设置一个生命周期 30s
        session.setMaxInactiveInterval(30);
        System.out.println("HspHttpSessionListener 监听到 session创建= " +
                session.getId());
        System.out.println("用户id=" + session.getId() + " 上线");
    }

    @Override
    public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {
        HttpSession session = httpSessionEvent.getSession();
        System.out.println("HspHttpSessionListener 监听到 session销毁= " +
                session.getId());
        System.out.println("用户id=" + session.getId() + " 离线");
    }
}

监听session属性改变

package com.hspedu.listener;

import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;

public class HspHttpSessionAttributeListener implements HttpSessionAttributeListener {
    @Override
    public void attributeAdded(HttpSessionBindingEvent httpSessionBindingEvent) {
        //HttpSession session = httpSessionBindingEvent.getSession();
        System.out.println("HspHttpSessionAttributeListener 监听到session添加属性" +
                httpSessionBindingEvent.getName() + "=" + httpSessionBindingEvent.getValue());
    }

    @Override
    public void attributeRemoved(HttpSessionBindingEvent httpSessionBindingEvent) {
        HttpSession session = httpSessionBindingEvent.getSession();

        System.out.println("HspHttpSessionAttributeListener 监听到session删除属性" +
                httpSessionBindingEvent.getName());
    }

    @Override
    public void attributeReplaced(HttpSessionBindingEvent httpSessionBindingEvent) {

        System.out.println("HspHttpSessionAttributeListener 监听到session修改属性" +
                httpSessionBindingEvent.getName() + "=" + httpSessionBindingEvent.getValue());
    }
}

监听request

package com.hspedu.listener;

import javax.servlet.ServletRequest;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.http.HttpServletRequest;

public class HspRequestListener implements ServletRequestListener {

    @Override
    public void requestInitialized(ServletRequestEvent servletRequestEvent) {
        System.out.println("HspRequestListener 监听到 request对象创建");
        ServletRequest servletRequest = servletRequestEvent.getServletRequest();
        System.out.println("记录访问日志....");
        System.out.println("访问IP= " + servletRequest.getRemoteAddr());
        System.out.println("访问的资源= " + ((HttpServletRequest)servletRequest).getRequestURL());
    }
    @Override
    public void requestDestroyed(ServletRequestEvent servletRequestEvent) {

        System.out.println("HspRequestListener 监听到 request对象被销毁");
    }


}