SpringBoot基于WebListener实现实时在线人数统计

一、引入依赖

    org.springframework.boot
    spring-boot-starter-web

二、application.properties文件设置

# 设置1分钟的有效时间
server.servlet.session.timeout=1m

三、计数服务

import org.springframework.stereotype.Service;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * @author qinxun
 * @date 2023-06-05
 * @Descripion: 计数服务
 */
@Service
public class CountService {

    static AtomicInteger atomicInteger = new AtomicInteger(0);

    /**
     * 新增在线人数
     */
    public void incr(int cnt) {
        atomicInteger.addAndGet(cnt);
    }

    /**
     * 获取当前在线的人数
     */
    public int getOnlineCnt() {
        return atomicInteger.get();
    }
}

四、session监听器

import com.example.quartzdemo.service.CountService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

/**
 * @author qinxun
 * @date 2023-06-05
 * @Descripion: session监听器
 */
@Component
@WebListener
public class LoginUserCountListener implements HttpSessionListener {

    @Autowired
    private CountService countService;

    @Override
    public void sessionCreated(HttpSessionEvent se) {
        System.out.println("新增一个用户");
        HttpSessionListener.super.sessionCreated(se);
        countService.incr(1);
    }

    @Override
    public void sessionDestroyed(HttpSessionEvent se) {
        System.out.println("销毁一个用户");
        HttpSessionListener.super.sessionDestroyed(se);
        countService.incr(-1);
    }
}

五、创建访问层

import com.example.quartzdemo.service.CountService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

/**
 * @author qinxun
 * @date 2023-06-05
 * @Descripion: 测试
 */
@RestController
public class WebController {

    @Autowired
    private CountService countService;

    /**
     * 登录
     */
    @RequestMapping("/login")
    public String login(String username, HttpServletRequest servletRequest) {
        HttpSession session = servletRequest.getSession();
        session.setAttribute("username", username);
        return "欢迎您:" + username + ",当前在线人数:" + countService.getOnlineCnt();
    }


    /**
     * 退出登陆
     */
    @RequestMapping("/logout")
    public String logount(HttpSession httpSession) {
        // 注销当前的session
        httpSession.invalidate();
        return "登出成功， 当前在线人数: " + countService.getOnlineCnt();
    }

}

六、测试