当前在线人数与历史访问量

最新推荐文章于 2023-02-15 00:05:32 发布

原创最新推荐文章于 2023-02-15 00:05:32 发布 · 426 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#数据库

web 专栏收录该内容

7 篇文章

订阅专栏

本文介绍了如何统计当前在线人数，包括通过创建监听器和修改index.jsp来实现。同时，也提到了历史访问量的统计，特别是针对登录页面的数据记录。

当前在线人数

1.创建监听器（servletContext创建）

package com.count;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
/*
    初始化:
         只有服务器的启动，才会创建servletContext对象。
        用于监听servletContext创建，一旦创建servletContext创建，则设置servletContext中的count值为0;
*/
@WebListener
/*
    这个注解的作用是启动监听，相当于在web.xml配置（
    <listener>
        <listener-class>com.cyl.count.InitServletContexListener</listener-class>
    </listener>
*/
public class InitServletContexListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        //获取ServletContext域对象
        ServletContext servletContext = servletContextEvent.getServletContext();
        //给ServletContext域对象，设置count=0
        servletContext.setAttribute("count",0);
    }
 
    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {
 
    }
}

2.监听在线人数，监听session的创建和销毁

package com.count;
 
import javax.servlet.ServletContext;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
 
/**
 * @监听在线人数，监听session的创建和销毁
 *     如果session创建 获取ServletContext中的count++,重新设置
 *     如果session销毁 获取ServletContext中的count--,重新设置
 */
@WebListener
public class OnlineNumberHttpSessionListener implements HttpSessionListener {
    @Override
    public void sessionCreated(HttpSessionEvent httpSessionEvent) {
        //1.获取session
        HttpSession session = httpSessionEvent.getSession();
        ServletContext servletContext = session.getServletContext();
        //2.获取counnt值，加1
        int count = (int) servletContext.getAttribute("count");
        count++;
        //3.把servlet存储到servletContext对象中
        servletContext.setAttribute("count",count);
    }
 
    @Override
    public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {
 
        //1.获取session
        HttpSession session = httpSessionEvent.getSession();
        ServletContext servletContext = session.getServletContext();
        //2.获取counnt值，减1
        int count = (int) servletContext.getAttribute("count");
        count++;
        //3.把servlet存储到servletContext对象中
        servletContext.setAttribute("count",count);
    }
}

3.修改index.jsp

    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <%@taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
    <html>
    <head>
      <title>$Title$</title>
    </head>
    <body>
    <h1>当前在线人数：${count}</h1>
    </body>
    </html>

历史访问量

import java.io.IOException;
import java.io.PrintWriter;
 
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
/**
 * Servlet implementation class countServlet1
 */
@WebServlet("/countServlet1")
public class countServlet1 extends HttpServlet {
    private static final long serialVersionUID = 1L;
 
    /**
     * @see HttpServlet#HttpServlet()
     */
    public countServlet1() {
        super();
        // TODO Auto-generated constructor stub
    }
 
    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置字符编码
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=utf-8");
 
 
 
        //获取全局的共享数据
        ServletContext servletContext = this.getServletContext();
 
        //获取计数器count
        Integer count = (Integer) servletContext.getAttribute("count");
 
        //如果获取的计算器对象为空 ，说明是第一次访问，并将count，放入servletCount
        if( servletContext.getAttribute("count") == null) {
            count = 1;
            servletContext.setAttribute("count", count);
        }else {
            //否则就不是第一次访问，将登陆的计数器进行加1的数据更新
            servletContext.setAttribute("count", count+1);
        }
 
        //将登陆的次数显示在页面上
        PrintWriter out =response.getWriter();
        out.print("<!DOCTYPE html>\r\n" +
                "<html>\r\n" +
                "<head>\r\n" +
                "<meta charset=\"UTF-8\">\r\n" +
                "<title>登陆网页次数统计</title>\r\n" +
                "</head>\r\n" +
                "<body>");
        out.print("<h1>");
        out.print("您是第 "+ servletContext.getAttribute("count")+"位访客");
        out.print("<h1>");
        out.print("</body>\r\n" +
                "</html>");
    }
 
    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }
 
}

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
  <%
    //统计网页访问量
    if (application.getAttribute("count") == null) {
      application.setAttribute("count", 0);//application.setAttribute("count", new Integer(0));
    }
    Integer count = (Integer) application.getAttribute("count");
    //使用application对象读取count参数的值，再在原值基础上累加1
    application.setAttribute("count", count + 1);//application.setAttribute("count", new Integer(count.intValue() + 1));
  %>
  <h2>
    <!-- 输出累加后的count参数对应的值 -->
    欢迎您访问，本页面已经被访问过 <font color="#ff0000"><%=application.getAttribute("count")%></font>次
  </h2>
  </body>
</html>

登录页面

    <%@page contentType="text/html; charset=utf-8"%>
    <%@page import="java.util.*" %>
    <%
    	String path  = request.getContextPath();
     %>
     
    <html>
    	<body>
    	
    		<form action="<%=path %>/Login" method="post">
    			账号：
    			<input type="text" name="username" />
    			<br />
    			密码：
    			<input type="password" name="password" />
    			<br />
    			<input type="submit" value="提交" />
    		</form>
     
    	</body>
    	
    </html>