JSP-JSP listener

Copyright: [Beijing] Java Youth: 456588754 https://blog.csdn.net/Amen_Wu/article/details/53510836

First, // Configure listener in web.xml

<listener>
 <listener-class>cn.news.lisener.UserLisener</listener-class>
 </listener>

Second, a write packet UserListener class at com.wu.listener

HttpSessionBindingListener Interface

valueBound(HttpSessionBindingEvent event)

When the object is added to the session, the method invoked by the container object is notified, no return value

valueUnbound(HttpSessionBindingEvent event)

When the object is removed from the session, the method invoked by the container object is notified, no return value

public class UserListener implements HttpSessionBindingListener {
//session生效
	public void valueBound(HttpSessionBindingEvent arg0) {
		Statistics.USER_ONLINE_STATISTICS++;
		
	}
	public void valueUnbound(HttpSessionBindingEvent arg0) {
		Statistics.USER_ONLINE_STATISTICS--;
	}
}	

// in UserServlet

UserListener ul = new UserListener();
		if (user != null) {
			// 如果正确，保存用户的状态信息
			if (user.getPwd().equals(upwd)) {
				System.out.println("登录成功");
				HttpSession session = request.getSession();
				session.setAttribute("loginuser", user.getUname());
				session.setAttribute("isadmin", user.getIsadmin());
				session.setAttribute("ul", ul);
				response.sendRedirect(request.getContextPath() + "/index.jsp");