雪花算法工具类

好的，雪花算法是一种生成分布式唯一ID的算法，可以用于分布式系统中的唯一ID生成。以下是一个Java版本的雪花算法工具类示例：

public class SnowflakeIdWorker {
    private static final long START_STMP = 1480166465631L;
    private static final long SEQUENCE_BIT = 12;
    private static final long MACHINE_BIT = 5;
    private static final long DATACENTER_BIT = 5;
    private static final long MAX_DATACENTER_NUM = -1L ^ (-1L << DATACENTER_BIT);
    private static final long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
    private static final long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);
    private static final long MACHINE_LEFT = SEQUENCE_BIT;
    private static final long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
    private static final long TIMESTAMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;
    private long datacenterId;
    private long machineId;
    private long sequence = 0L;
    private long lastStmp = -1L;

    public SnowflakeIdWorker(long datacenterId, long machineId) {
        if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) {
            throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0");
        }
        if (machineId > MAX_MACHINE_NUM || machineId < 0) {
            throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
        }
        this.datacenterId = datacenterId;
        this.machineId = machineId;
    }

    public synchronized long nextId() {
        long currStmp = getNewstmp();
        if (currStmp < lastStmp) {
            throw new RuntimeException("Clock moved backwards.  Refusing to generate id");
        }
        if (currStmp == lastStmp) {
            sequence = (sequence + 1) & MAX_SEQUENCE;
            if (sequence == 0L) {
                currStmp = getNextMill();
            }
        } else {
            sequence = 0L;
        }
        lastStmp = currStmp;
        return (currStmp - START_STMP) << TIMESTAMP_LEFT | datacenterId << DATACENTER_LEFT | machineId << MACHINE_LEFT | sequence;
    }

    private long getNextMill() {
        long mill = getNewstmp();
        while (mill <= lastStmp) {
            mill = getNewstmp();
        }
        return mill;
    }

    private long getNewstmp() {
        return System.currentTimeMillis();
    }

    public static void main(String[] args) {
        SnowflakeIdWorker idWorker = new SnowflakeIdWorker(0, 0);
        for (int i = 0; i < 10; i++) {
            System.out.println(idWorker.nextId());
        }
    }
}

这个工具类中，我们使用了Java的同步机制来保证线程安全，同时使用了位运算来生成ID，保证了ID的唯一性和可读性。