javaweb監(jiān)聽(tīng)器接口-觀察者模式

javaweb監(jiān)聽(tīng)器接口有8個(gè)分別是
ServletRequestListener,
HttpSessionListener,
ServletContextListener,

ServletRequestAttributeListener,
HttpSessionAttributeListener,
ServletContextAttributeLister,

HttpSessionActivationListener
HttpSessionBindingListener

分別說(shuō)明
1.域?qū)ο蟊O(jiān)聽(tīng)3個(gè)，用來(lái)監(jiān)聽(tīng)域?qū)ο蟮膭?chuàng)建和銷毀
ServletRequestListener,創(chuàng)建：請(qǐng)求開(kāi)始 銷毀：響應(yīng)結(jié)束
HttpSessionListener,創(chuàng)建：第一次調(diào)用request.getSession() 銷毀：30分鐘 調(diào)用invalidate() 非正常關(guān)閉
ServletContextListener,創(chuàng)建:拂去其啟動(dòng) 銷毀：服務(wù)器正常關(guān)閉

都需要在web.xml中配置
<listener>
<listener-class>com.test.servlet.MyLister</listener-class>
</listener>

2.域?qū)ο髮傩员O(jiān)聽(tīng)3個(gè)，用來(lái)監(jiān)聽(tīng)域?qū)ο髮傩缘奶砑?，變更和刪除
ServletRequestAttributeListener,

HttpSessionAttributeListener,
ServletContextAttributeLister,

都需要在web.xml中配置
<listener>
<listener-class>com.test.servlet.MyLister</listener-class>
</listener>

3.特殊的javabean監(jiān)聽(tīng)
HttpSessionActivationListener
監(jiān)聽(tīng)session作用域的數(shù)據(jù)綁定和解綁
綁定：javabean實(shí)現(xiàn)該接口，并添加到session作用域
解綁：javabean實(shí)現(xiàn)該接口，并從session中作用域移除

不需要在web.xml中配置

HttpSessionBindingListener監(jiān)聽(tīng)session作用域的鈍化和活化
鈍化：將session作用域數(shù)據(jù)從內(nèi)存寫到硬盤上
活化：將session作用域數(shù)據(jù)從硬盤上讀取到內(nèi)存中

注意javabean不僅僅要實(shí)現(xiàn)該接口，還必須實(shí)現(xiàn)序列化接口