WebListener显示访问数量
getServletContext通过创建域来显示访问数量

| package com.msb; |
| |
| import javax.servlet.ServletContext; |
| import javax.servlet.annotation.WebListener; |
| import javax.servlet.http.HttpSession; |
| import javax.servlet.http.HttpSessionContext; |
| import javax.servlet.http.HttpSessionEvent; |
| import javax.servlet.http.HttpSessionListener; |
| @WebListener |
| public class HttpLis implements HttpSessionListener { |
| public void sessionCreated(HttpSessionEvent se) { |
| |
| HttpSession session = se.getSession(); |
| |
| ServletContext application = session.getServletContext(); |
| Object attribute = application.getAttribute("count"); |
| if (attribute==null){ |
| servletContext.setAttribute("count",1); |
| }else { |
| int count = (int)attribute; |
| servletContext.setAttribute("count",++count); |
| } |
| } |
| public void sessionDestroyed(HttpSessionEvent se) { |
| HttpSession session = se.getSession(); |
| ServletContext servletContext = session.getServletContext(); |
| int count = (int)servletContext.getAttribute("count"); |
| servletContext.setAttribute("count",--count); |
| } |
| } |
| |
| <%-- |
| Created by IntelliJ IDEA. |
| User: tomel |
| Date: 2022/5/29 |
| Time: 7:41 |
| To change this template use File | Settings | File Templates. |
| --%> |
| <%@ page contentType="text/html;charset=UTF-8" language="java" %> |
| <html> |
| <head> |
| <title>$Title$</title> |
| </head> |
| <body> |
| welcome to my new page |
| 当前在线人数为: |
| ${applicationScope.count} |
| |
| </body> |
| </html> |
| |
| package com.msb; |
| |
| import javax.servlet.ServletException; |
| import javax.servlet.annotation.WebServlet; |
| import javax.servlet.http.HttpServlet; |
| import javax.servlet.http.HttpServletRequest; |
| import javax.servlet.http.HttpServletResponse; |
| import javax.servlet.http.HttpSession; |
| import java.io.IOException; |
| @WebServlet("/fileout.do") |
| public class fileout extends HttpServlet { |
| @Override |
| protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { |
| HttpSession session = req.getSession(); |
| session.invalidate(); |
| } |
| } |
| |
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