JavaWeb Listener

1 ServletContextListener

监听ServletContext对象被创建和销毁的Servlet监听器

开发：>创建一个实现了ServletContextListener的类并且实现里面的两个方法

public class HelloServletContextListener implements ServletContextListener

public class HelloServletContextListener implements ServletContextListener {

    public void contextDestroyed(ServletContextEvent sce) {
        // TODO Auto-generated method stub
        System.out.println("销毁");

    }

    public void contextInitialized(ServletContextEvent sce) {
        // TODO Auto-generated method stub
        System.out.println("创建");

    }

>并在web.xml里配置该Listener

<!-- 配置listener -->
    <listener>
    <listener-class>cn.stud.wlc.listener.HelloServletContextListener</listener-class>
    </listener>

>ServletContextListener最常用在web应用加载时对当前web应用的相关资源进行初始化操作（创建数据库链接池。。。）

（2,3）ServletRequestListener& HttpSessionListener和ServletContextListener类似

public class HelloServletContextListener implements ServletContextListener,HttpSessionListener,ServletRequestListener {

    public void contextDestroyed(ServletContextEvent sce) {
        // TODO Auto-generated method stub
        System.out.println("销毁");

    }

    public void contextInitialized(ServletContextEvent sce) {
        // TODO Auto-generated method stub
        System.out.println("创建");

    }

    public void requestDestroyed(ServletRequestEvent sre) {
        // TODO Auto-generated method stub

    }

    public void requestInitialized(ServletRequestEvent sre) {
        // TODO Auto-generated method stub

    }

    public void sessionCreated(HttpSessionEvent se) {
        // TODO Auto-generated method stub

    }

    public void sessionDestroyed(HttpSessionEvent se) {
        // TODO Auto-generated method stub

    }

}