Springboot3 implementation example of using redis to generate a unique order number

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@RestController
public class distr_lock {
    @Resource
    private RedisTemplate<String,String> redisTemplate;


    @GetMapping("/order")
    public void order() {
        for (int i = 0; i < 50; i++) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    for (int i = 0; i < 20; i++) {
                        String s = generateOrderId();
                        (s);
                    }
                }
            }).start();
        }
    }

    /**
      * We can adopt such a strategy,
      * Time is accurate to seconds + 7 digits of self-incremental number
      * This can achieve no more than 10 million orders placed by the same user in the same second
      * Then use time to create a key in redis, and then expire in 30 seconds
      */
    public String generateOrderId(){
        DateTimeFormatter formatter = new DateTimeFormatterBuilder()
                .appendValue(, 4) // Year, 4 digits                .appendValue(ChronoField.MONTH_OF_YEAR, 2) // Month, 2 digits                .appendValue(ChronoField.DAY_OF_MONTH, 2) // Date, 2 digits                .appendValue(ChronoField.HOUR_OF_DAY, 2) // Hours, 2 digits                .appendValue(ChronoField.MINUTE_OF_HOUR, 2) // Minutes, 2 digits                .appendValue(ChronoField.SECOND_OF_MINUTE, 2) // seconds, 2 digits                .toFormatter();

        // Get the string representation of the current time, without using - or: as a separator        String currentDateTime = ().format(formatter);
//        Long count = getAndExpireCounter(currentDateTime);
        Long count = getAndExpireCounterByLua(currentDateTime);
        String format = ("%07d", count);
        return currentDateTime + format;
    }



    public Long getAndExpireCounter(String key) {
        // Get Redis connection to execute transactions        Long increment = 0L;
        increment = ().increment(key);
        if (increment!=null && increment == 1) {
            // Set the expiration time, no transaction or lua script is used here            // Because I think the above autoincrement operation is atomic, that is, you will definitely get a value of 1            // If the redis service crashes and the expiration time is not set at this point, then we            // The service will also crash, and this key will always exist on the server, and this problem will occur, for the sake of rigor.            // It is best to use lua scripts to write, as the project will ensure more reliable results            (key, 30, );
        }
        // Get the value after increasing        return increment;
    }
	
	/**
      * The function of the entire script is:
      * 1. Check whether a key exists in Redis.
      * 2. If the key does not exist, set the value of the key to 1, and set the expiration time of 60 seconds for it, and then return 1.
      * 3. If the key already exists, increase its value by 1 and return the added new value.
      * Redis is atomic when executing Lua scripts, which means that during the execution of this script,
      * No other scripts or commands modify this key at the same time, thus ensuring the atomicity and consistency of the operation.
      * @param key
      * @return
      */
    public Long getAndExpireCounterByLua(String key) {
        // Define Lua scripts        String script =
                "if ('EXISTS', KEYS[1]) == 0 then " +
                        "   ('SET', KEYS[1], 1) " +
                        "   ('EXPIRE', KEYS[1], 30) " +
                        "   return 1 " +
                        "else " +
                        "   return ('INCR', KEYS[1]) " +
                        "end";

        // Use Redis's script to execute functions        DefaultRedisScript<Long> redisScript = new DefaultRedisScript<>();
        (script);
        ();

        // Execute the script        return (redisScript, (key));
    }