1.基本介绍

2.ServletContextListener

1.基本介绍

2.创建maven项目，导入依赖

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
    </dependency>

3.代码演示

1.实现ServletContextListener接口

package listener;

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

/**
 * @author 孙显圣
 * @version 1.0
 */
public class ServletContextListener implements javax.servlet.ServletContextListener {
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        ServletContext servletContext = servletContextEvent.getServletContext();
        System.out.println("监听到servletContext创建");
    }

    public void contextDestroyed(ServletContextEvent servletContextEvent) {
        ServletContext servletContext = servletContextEvent.getServletContext();
        System.out.println("监听到servletContext销毁 ");
    }
}

2.配置web.xml

  <listener>
    <listener-class>listener.ServletContextListener</listener-class>
  </listener>

3.结果

3.ServletContextAttributeListener监听器

1.基本介绍

2.代码实例

1.ServletContextAttributeListener.java

package listener;

import javax.servlet.ServletContextAttributeEvent;

/**
 * @author 孙显圣
 * @version 1.0
 */
public class ServletContextAttributeListener implements javax.servlet.ServletContextAttributeListener {
    public void attributeAdded(ServletContextAttributeEvent servletContextAttributeEvent) {
        System.out.println("ServletContextAttributeListener监听到添加属性" + servletContextAttributeEvent.getName()
        + servletContextAttributeEvent.getValue());
    }

    public void attributeRemoved(ServletContextAttributeEvent servletContextAttributeEvent) {
        System.out.println("ServletContextAttributeListener监听到删除属性" + servletContextAttributeEvent.getName()
                + servletContextAttributeEvent.getValue());
    }

    public void attributeReplaced(ServletContextAttributeEvent servletContextAttributeEvent) {
        System.out.println("ServletContextAttributeListener监听到修改属性" + servletContextAttributeEvent.getName()
                + servletContextAttributeEvent.getValue());
    }
}

2.配置web.xml

  <listener>
    <listener-class>listener.ServletContextAttributeListener</listener-class>
  </listener>

3.创建servlet演示

package servlet;

import javax.servlet.ServletContext;
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 java.io.IOException;

/**
 * @author 孙显圣
 * @version 1.0
 */
@WebServlet(urlPatterns = "/modify")
public class modifyServletContextAttribute extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext servletContext = super.getServletContext();
        //添加
        servletContext.setAttribute("name","孙显圣");
        //替换
        servletContext.setAttribute("name","李白");
        //删除
        servletContext.removeAttribute("name");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

4.结果

4.HttpSessionListener

1.基本介绍

2.代码实例

1.HttpSessionListener.java

package listener;

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

/**
 * @author 孙显圣
 * @version 1.0
 */
public class HttpSessionListener implements javax.servlet.http.HttpSessionListener {
    public void sessionCreated(HttpSessionEvent httpSessionEvent) {
        HttpSession session = httpSessionEvent.getSession();
        System.out.println("HttpSessionListener监听到session创建id为" + session.getId());
    }

    public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {
        HttpSession session = httpSessionEvent.getSession();
        System.out.println("HttpSessionListener监听到session销毁id为" + session.getId());
    }
}

2.配置web.xml

  <listener>
    <listener-class>listener.HttpSessionListener</listener-class>
  </listener>

3.创建servlet演示

package servlet;


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;
import java.io.IOException;

/**
 * @author 孙显圣
 * @version 1.0
 */
@WebServlet(urlPatterns = "/modifySession")
public class modifySession extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建session
        HttpSession session = req.getSession();
        //删除session
        session.invalidate();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

4.结果

5.HttpSessionAttributeListener

1.基本介绍

2.代码实例

1.HttpSessionAttributeListener.java

package listener;

import javax.servlet.http.HttpSessionBindingEvent;

/**
 * @author 孙显圣
 * @version 1.0
 */
public class HttpSessionAttributeListener implements javax.servlet.http.HttpSessionAttributeListener {
    public void attributeAdded(HttpSessionBindingEvent httpSessionBindingEvent) {
        String name = httpSessionBindingEvent.getName();
        System.out.println("监听到session创建属性：" + name);
    }

    public void attributeRemoved(HttpSessionBindingEvent httpSessionBindingEvent) {
        String name = httpSessionBindingEvent.getName();
        System.out.println("监听到session删除属性：" + name);
    }

    public void attributeReplaced(HttpSessionBindingEvent httpSessionBindingEvent) {
        String name = httpSessionBindingEvent.getName();
        System.out.println("监听到session替换属性：" + name);
    }
}

2.配置web.xml

  <listener>
    <listener-class>listener.HttpSessionAttributeListener</listener-class>
  </listener>

3.创建servlet演示

package servlet;

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;
import java.io.IOException;

/**
 * @author 孙显圣
 * @version 1.0
 */
@WebServlet(urlPatterns = "/modifySessionAttribute")
public class modifySessionAttribute extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        HttpSession session = req.getSession();
        session.setAttribute("name","孙显圣");
        session.setAttribute("name","李白");
        session.removeAttribute("name");
    }
}

4.结果

6.ServletRequestListener

1.基本介绍

2.代码实例

1.ServletRequestListener.java

package listener;

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

/**
 * @author 孙显圣
 * @version 1.0
 */
public class ServletRequestListener implements javax.servlet.ServletRequestListener {
    public void requestDestroyed(ServletRequestEvent servletRequestEvent) {
        System.out.println("ServletRequestListener 监听到 request对象销毁");
    }

    public void requestInitialized(ServletRequestEvent servletRequestEvent) {
        System.out.println("ServletRequestListener 监听到 request对象创建");
        ServletRequest servletRequest = servletRequestEvent.getServletRequest();
        //可以向下转型为HttpServletRequest，获取更多信息
        System.out.println("访问ip：" + servletRequest.getRemoteAddr());
        System.out.println("访问资源：" + ((HttpServletRequest)servletRequest).getRequestURL());
    }
}

2.配置web.xml

  <listener>
    <listener-class>listener.ServletRequestListener</listener-class>
  </listener>

3.结果

7.其他监听器

8.监听器小结

1.创建监听器

1.基本概念

2.创建方法

1. 实现接口，进行相应操作
2. 配置web.xml（告诉tomcat）

2.ServletContextListener

3.ServletContextAttributeListener

4.HttpSessionListener

5.HttpSessionAttributeListener

6.ServletRequestListener