HttpSessionAttributeListener的用法和实例

4）HttpSessionAttributeListener：

HttpSessionAttributeListener能监测到有人正在往HttpSession里添加属性。你可以采取相应的措施。

例 2.2.4.1

package com;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
public class MyHttpSessionAttributeListener implements HttpSessionAttributeListener  {
    public void attributeAdded(HttpSessionBindingEvent arg0) {
        System.out.println("增加了" + arg0.getName() + " " +
                arg0.getValue() );        
    }
    public void attributeRemoved(HttpSessionBindingEvent arg0) {
        System.out.println("去除了" + arg0.getName() + " " +
                arg0.getValue() );
    }
    public void attributeReplaced(HttpSessionBindingEvent arg0) {
        System.out.println("取代了" + arg0.getName() + " " +
                arg0.getValue()+"现在的新值是"+arg0.getSession().getAttribute(arg0.getName()) );
    }
}

web.xml加入下面这段话

  <listener>
    <listener-class>com.MyHttpSessionAttributeListener</listener-class>
  </listener>

更多请看：https://blog.youkuaiyun.com/qq_44594371/article/details/103188512