springboot使用HttpSessionListener监听器统计在线用户数

àì夳堔傛蜴生んèń 2022-09-04 15:59 299阅读 0赞

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzU4NTc0_size_16_color_FFFFFF_t_70]

###  ###

*   *  实体类
     *  自定义事件
     *  自定义监听器
     *  使用HttpSessionListener作监听器
     *  Servlet监听器
     *  controller层

## 实体类 ##

public class User { 
    
        private Long id;
    
        private String username;
    
        private String password;
    
        public Long getId() { 
            return id;
        }
    
        public void setId(Long id) { 
            this.id = id;
        }
    
        public String getUsername() { 
            return username;
        }
    
        public void setUsername(String username) { 
            this.username = username;
        }
    
        public String getPassword() { 
            return password;
        }
    
        public void setPassword(String password) { 
            this.password = password;
        }
    
        public User(Long id, String username, String password) { 
            this.id = id;
            this.username = username;
            this.password = password;
        }
    
        public User() { 
        }
    }

## 自定义事件 ##

public class MyEvent extends ApplicationEvent { 
    
        private User user;
    
        public MyEvent(Object source, User user) { 
            super(source);
            this.user = user;
        }
    
        public User getUser() { 
            return user;
        }
    
        public void setUser(User user) { 
            this.user = user;
        }
    }

service:

```java
    @Service
    public class UserService { 
    
        @Resource
        private ApplicationContext applicationContext;
    
        /** * 发布事件 * @return */
        public User getUser2() { 
            User user = new User(1L, "小明", "123456");
            // 发布事件
            MyEvent event = new MyEvent(this, user);
            applicationContext.publishEvent(event);
            return user;
        }
    
        /** * 获取用户信息 * @return */
        public User getUser() { 
            // 实际中会根据具体的业务场景，从数据库中查询对应的信息
            return new User(1L, "小明", "123456");
        }
    }

## 自定义监听器 ##

@Component
    public class MyEventListener implements ApplicationListener<MyEvent> { 
        @Override
        public void onApplicationEvent(MyEvent myEvent) { 
            // 把事件中的信息获取到
            User user = myEvent.getUser();
            // 处理事件，实际项目中可以通知别的模块或者处理其他逻辑等等
            System.out.println("用户名：" + user.getUsername());
            System.out.println("密码：" + user.getPassword());
    
        }
    }

## 使用HttpSessionListener作监听器 ##

@Component
    public class MyHttpSessionListener implements HttpSessionListener { 
    
        private static final Logger logger = LoggerFactory.getLogger(MyHttpSessionListener.class);
    
        /** * 记录在线的用户数量 */
        public Integer count = 0;
    
        @Override
        public synchronized void sessionCreated(HttpSessionEvent httpSessionEvent) { 
            logger.info("新用户上线了");
            count++;
    
            httpSessionEvent.getSession().getServletContext().setAttribute("count", count);
        }
    
        @Override
        public synchronized void sessionDestroyed(HttpSessionEvent httpSessionEvent) { 
            logger.info("用户下线了");
            count--;
            httpSessionEvent.getSession().getServletContext().setAttribute("count", count);
        }
    }

## Servlet监听器 ##

@Component
    public class MyServletContextListener implements ApplicationListener<ContextRefreshedEvent> { 
    
        @Override
        public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) { 
            // 先获取到application上下文
            ApplicationContext applicationContext = contextRefreshedEvent.getApplicationContext();
            // 获取对应的service
            UserService userService = applicationContext.getBean(UserService.class);
            User user = userService.getUser();
            // 获取application域对象，将查到的信息放到application域中
            ServletContext application = applicationContext.getBean(ServletContext.class);
            application.setAttribute("user", user);
        }
    }

@Component
    public class MyServletRequestListener implements ServletRequestListener { 
    
        private static final Logger logger = LoggerFactory.getLogger(MyServletRequestListener.class);
    
        @Override
        public void requestInitialized(ServletRequestEvent servletRequestEvent) { 
            HttpServletRequest request = (HttpServletRequest) servletRequestEvent.getServletRequest();
            logger.info("session id为：{}", request.getRequestedSessionId());
            logger.info("request url为：{}", request.getRequestURL());
    
            request.setAttribute("name", "小明");
        }
    
        @Override
        public void requestDestroyed(ServletRequestEvent servletRequestEvent) { 
    
            logger.info("request end");
            HttpServletRequest request = (HttpServletRequest) servletRequestEvent.getServletRequest();
            logger.info("request域中保存的name值为：{}", request.getAttribute("name"));
    
        }
    
    }

## controller层 ##

@RestController
    @RequestMapping("/listener")
    public class TestController { 
    
        @Resource
        private UserService userService;
    
        @GetMapping("/user")
        public User getUser(HttpServletRequest request) { 
            ServletContext application = request.getServletContext();
            return (User) application.getAttribute("user");
        }
    
        /** * 获取当前在线人数 * @param request * @return */
    
    
        @GetMapping("/total2")
        public String getTotalUser(HttpServletRequest request, HttpServletResponse response) { 
            Cookie cookie;
            try { 
                // 把sessionId记录在浏览器中
                cookie = new Cookie("JSESSIONID", URLEncoder.encode(request.getSession().getId(), "utf-8"));
                cookie.setPath("/");
                //设置cookie有效期为2天，设置长一点
                cookie.setMaxAge( 48*60 * 60);
                response.addCookie(cookie);
            } catch (UnsupportedEncodingException e) { 
                e.printStackTrace();
            }
            Integer count = (Integer) request.getSession().getServletContext().getAttribute("count");
            return "当前在线人数：" + count;
        }
    
        @GetMapping("/request")
        public String getRequestInfo(HttpServletRequest request) { 
            System.out.println("requestListener中的初始化的name数据：" + request.getAttribute("name"));
            return "success";
        }
    
        @GetMapping("/publish")
        public User publishEvent() { 
            return userService.getUser2();
        }
    
    }

运行结果：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzU4NTc0_size_16_color_FFFFFF_t_70 1]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzU4NTc0_size_16_color_FFFFFF_t_70]: /images/20220829/facda27ee32842d787c2f958d6d1bb9f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzU4NTc0_size_16_color_FFFFFF_t_70 1]: /images/20220829/42b318ed63c643aaa8e95d39e7f301c1.png