java 雪花算法生成 工具类

### Java 实现雪花算法工具类 雪花算法是一种高效的分布式唯一ID生成方案，在Java中可以通过创建一个工具类来实现该功能。下面展示的是一个典型的Snowflake ID生成器的实现方式[^1]。 ```java public class SnowFlake { // 起始的时间戳 private final static long START_TIMESTAMP = 1288834974657L; // 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 DATACENTER_BIT = 5;// 数据中心占用的位数 // 每一部分的最大值 private final static long MAX_DATACENTER_NUM = ~(-1L << DATACENTER_BIT); private final static long MAX_MACHINE_NUM = ~(-1L << MACHINE_BIT); private final static long MAX_SEQUENCE = ~(-1L << SEQUENCE_BIT); // 每一部分向左移动的位数 private final static long MACHINE_LEFT = SEQUENCE_BIT; private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT; private final static long TIMESTAMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT; private long datacenterId; //数据中心 private long machineId; //机器标识 private long sequence = 0L; //序列号 public SnowFlake(long datacenterId, long machineId) { if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) { throw new IllegalArgumentException("datacenter Id can't be greater than " + MAX_DATACENTER_NUM + " or less than 0"); } if (machineId > MAX_MACHINE_NUM || machineId < 0) { throw new IllegalArgumentException("machine Id can't be greater than " + MAX_MACHINE_NUM + " or less than 0"); } this.datacenterId = datacenterId; this.machineId = machineId; } /** * 下一ID的方法 */ public synchronized long nextId() { long currTimestamp = timeGen(); if (currTimestamp < lastTimestamp) { try { throw new Exception("Clock moved backwards. Refusing to generate id"); } catch (Exception e) { e.printStackTrace(); } } if (lastTimestamp == currTimestamp) { // 当前毫秒内，则+1 sequence = (sequence + 1) & MAX_SEQUENCE; if (sequence == 0) { // 当前毫秒内计数满了，则等待下一秒 currTimestamp = tilNextMillis(lastTimestamp); } } else { sequence = 0L; } lastTimestamp = currTimestamp; return ((currTimestamp - START_TIMESTAMP) << TIMESTAMP_LEFT) | (datacenterId << DATACENTER_LEFT) | (machineId << MACHINE_LEFT) | sequence; } protected long tilNextMillis(final long lastTimestamp) { long timestamp = timeGen(); while (timestamp <= lastTimestamp) { timestamp = timeGen(); } return timestamp; } protected long timeGen() { return System.currentTimeMillis(); } } ``` 为了提高性能并减少资源消耗，建议采用单例模式实例化此类或通过Spring框架进行依赖注入管理，从而避免频繁的新建操作带来的开销[^2]。