常见的监听器

ServletContextListener

监听servletContext对象的创建以及销毁

contextInitialized(ServletContextEvent arg0)    
contextDestroyed(ServletContextEvent arg0)

HttpSessionListener

监听session对象的创建以及销毁

sessionCreated(HttpSessionEvent se) 
sessionDestroyed(HttpSessionEvent se)

ServletRequestListener

监听request对象的创建以及销毁

requestInitialized(ServletRequestEvent sre)
requestDestroyed(ServletRequestEvent sre)

ServletContextAttributeListener

监听servletContext对象中属性的改变

//添加属性时执行
attributeAdded(ServletContextAttributeEvent event) 
//修改属性时执行
attributeReplaced(ServletContextAttributeEvent event)
//删除属性时执行
attributeRemoved(ServletContextAttributeEvent event) 

HttpSessionAttributeListener

监听session对象中属性的改变

//添加属性时执行
attributeAdded(HttpSessionBindingEvent event)
//修改属性时执行
attributeReplaced(HttpSessionBindingEvent event)
//删除属性时执行
attributeRemoved(HttpSessionBindingEvent event)

ServletRequestAttributeListener

监听request对象中属性的改变

//添加属性时执行
attributeAdded(ServletRequestAttributeEvent srae)
//修改属性时执行
attributeReplaced(ServletRequestAttributeEvent srae)
//删除属性时执行
attributeRemoved(ServletRequestAttributeEvent srae)

常见的监听器引用自https://blog.csdn.net/m0_38075425/article/details/81164501。