Using redis bitmap to realize personnel online monitoring

One ： Business scenario

It is necessary to display and count the online status of some people （ The same day or a specified number of days ）

Two ： Code

Here I am using websocket Heartbeat mechanism redis bitmap Data insertion

      /** *  receive userId */
    private String userId = "";
    
    // Omit here - Successfully set up websocket Assign values when connecting userId
    
    /** *  The heartbeat detection  * * @param message  The message sent by the client  */
    @OnMessage
    public void onMessage(String message, Session session) throws IOException {
    
  			// The online status is mainly set here - Instance independent code 
            redisTemplate.opsForValue().set(Constant.CASE_ONLINE+this.userId
                    ,System.currentTimeMillis(),Constant.ONLINE_MAX_ALIVE_SECOND, TimeUnit.SECONDS);
            // The same day of the current month --（ Since there is error in directly calculating the number of milliseconds in a day, the following stupid method is used to get the current number of steps ）
            String yyyyMMdd = DateUtil.format(new Date(), "yyyyMMdd");
            int m = DateUtil.thisMinute();
            int hour = DateUtil.thisHour(true);
            // Get the number of steps -- In minutes per day 00:00-24:00-- The most steps a day 1,440 position 
            long index = hour* 60L +m;
            // To set up KEY value 
            String key="ONLINE:"+this.userId+":"+yyyyMMdd;
            // Deposit in redis in ,index Represents the current number of steps 
            redisTemplate.opsForValue().setBit(key, index, true);
            // Detect whether there is an expiration time , Set if none 7 Days overdue 
            Long expire = redisTemplate.getExpire(key);
            if (expire==null || expire < 1L){
    
                redisTemplate.expire(key,7,TimeUnit.DAYS);
            }
     

    }

The effect is as follows , Note that the place marked is set to binary To see 01

Let's write an interface to query the online situation

    /** * @Author: OUO * @DateTime: 2022/6/1 11:17 * @Description:  Get the online status of users -- On the same day or on a specified day , The format is YYYYMMDD */
    @RequestMapping("/queryOnlineInfo")
    public Result queryOnlineInfo(String userId,String times){
    
        Map<String,Object> map=new HashMap<>();
        List<String> dateList=new ArrayList<>();
        String yyyyMMdd = times;
        int m = DateUtil.thisMinute();
        int hour = DateUtil.thisHour(true);
        // Get the number of steps so far ,-- In minutes 
        long index = hour* 60L +m;
        // Set up KEY value 
        String key="ONLINE:"+userId+":"+yyyyMMdd;
        // Query the total number of valid steps inserted by yourself , For example, you successfully insert 10 Time , The result here is 10-- This is not used yet , Generally used for statistics 
        Long execute = jsonRedisTemplate.execute((RedisCallback<Long>) conn -> conn.bitCount(key.getBytes()));
        List<String> list = new ArrayList<>();
        for (int i = 0; i < index; i++) {
    
            // According to the number of steps   Get all the values step by step and assign values 
            Boolean bit = jsonRedisTemplate.opsForValue().getBit("ONLINE:" + userId + ":" + yyyyMMdd, i);
            // establish Y Axis data source 
            list.add((Boolean.TRUE.equals(bit) ?" On-line ":" offline "));
            // establish X Axis data source 
            Date dateTime = DateUtil.offsetMinute(DateUtil.beginOfDay(new Date()),i);
            String format = DateUtil.format(dateTime, "HH:mm");
            dateList.add(format);
        }
        // In order to meet Echarts Figure so set XY
        map.put("x",dateList);
        map.put("y",list);
        return Result.build(true,"200",map," The query is successful ");
    }
}

design sketch