雪花算法生成器

雪花算法

package com.ccb.utils; public class SnowflakeIdGenerator { // 定义雪花 ID 的各部分位数 private static final long TIMESTAMP_BITS = 41L; private static final long NODE_ID_BITS = 10L; private static final long SEQUENCE_BITS = 12L; // 定义起始时间戳（可根据实际情况调整） private static final long EPOCH = 1609459200000L; // 定义最大取值范围 private static final long MAX_NODE_ID = (1L << NODE_ID_BITS) - 1; private static final long MAX_SEQUENCE = (1L << SEQUENCE_BITS) - 1; // 定义偏移量 private static final long TIMESTAMP_SHIFT = NODE_ID_BITS + SEQUENCE_BITS; private static final long NODE_ID_SHIFT = SEQUENCE_BITS; private final long nodeId; private long lastTimestamp = -1L; private long sequence = 0L; public SnowflakeIdGenerator(long nodeId) { if (nodeId < 0 || nodeId > MAX_NODE_ID) { throw new IllegalArgumentException("Invalid node ID"); } this.nodeId = nodeId; } public synchronized long generateId() { long currentTimestamp = timestamp(); if (currentTimestamp < lastTimestamp) { throw new IllegalStateException("Clock moved backwards"); } if (currentTimestamp == lastTimestamp) { sequence = (sequence + 1) & MAX_SEQUENCE; if (sequence == 0) { currentTimestamp = untilNextMillis(lastTimestamp); } } else { sequence = 0L; } lastTimestamp = currentTimestamp; return ((currentTimestamp - EPOCH) << TIMESTAMP_SHIFT) | (nodeId << NODE_ID_SHIFT) | sequence; } private long timestamp() { return System.currentTimeMillis(); } private long untilNextMillis(long lastTimestamp) { long currentTimestamp = timestamp(); while (currentTimestamp <= lastTimestamp) { currentTimestamp = timestamp(); } return currentTimestamp; } public static void main(String[] args) { // 创建一个雪花 ID 生成器实例，传入节点 ID SnowflakeIdGenerator idGenerator = new SnowflakeIdGenerator(1); // 生成 ID long id = idGenerator.generateId(); System.out.println(id); } } package com.ccb.utils; public class Snowflake