雪花算法代码

雪花算法是一种生成全局唯一 ID 的算法，它可以在分布式系统中使用，以避免 ID 冲突的问题。

下面是一个使用 Java 语言实现的雪花算法的代码示例：

public class SnowflakeIdGenerator {
    // 起始的时间戳
    private final static long START_STAMP = 1480166465631L;

    // 每一部分占用的位数
    private final static long SEQUENCE_BIT = 12; //序列号占用的位数
    private final static long MACHINE_BIT = 5;   //机器标识占用的位数
    private final static long DATA_CENTER_BIT = 5;//数据中心占用的位数

    // 每一部分的最大值
    private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);
    private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
    private final static long MAX_DATA_CENTER_NUM = -1L ^ (-1L << DATA_CENTER_BIT);

    // 每一部分向左的位移
    private final static long MACHINE_LEFT = SEQUENCE_BIT;
    private final static long DATA_CENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
    private final static long TIMESTAMP_LEFT = DATA_CENTER_LEFT + DATA_CENTER_BIT;

    private long dataCenterId;  //数据中心
    private long machineId;     //机器标识
    private long sequence = 0L; //序列号
    private long lastStamp = -1L;//上一次时间戳

    public SnowflakeIdGenerator(long dataCenterId, long machineId) {
        if (dataCenterId > MAX_DATA_CENTER_NUM || dataCenterId < 0) {
            throw new IllegalArgumentException("dataCenterId can't be greater than MAX_DATA_CENTER_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;
    }

    //产生下一个ID
    public synchronized long nextId() {
        long currStamp = getNewStamp();
        if (currStamp <