监听器 Listener
.ServletContextListener·HttpSessionListener·servletRequestListener

作用:能够针对创建和销毁定又不网的行为

ServletContextListener
coverride

public void contextInitialized(ServletContextEvent sce){
)

coverride
public void contextoestroyed(ServletContextEvent sce){
)

HttpSessionListener

Goverride
public void sessioncreated(HttpsessionEvent se){
}
Coverride
public void sessionDestroyed(HttpsessionEvent se)(
1
一定要在监听器的类上加上webListener，否则该监听器不会被启动

过滤器 Filter

精准匹配 /a.jsp

扩展名匹配*.jsp

路径匹配/manager/*

匹配所有/*

public void doFilter(request,respose,chain) throws IOException,ServletException{

}