package com.ruoyi.payment.infrastructure.util;
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/**
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* 雪花算法ID生成器
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*
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* @author ruoyi
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*/
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public class SnowflakeIdGenerator {
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// 起始时间戳 (2020-01-01)
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private static final long START_TIMESTAMP = 1577808000000L;
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// 每部分占用的位数
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private static final long SEQUENCE_BIT = 12; // 序列号占用的位数
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private static final long MACHINE_BIT = 5; // 机器标识占用的位数
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private static final long DATACENTER_BIT = 5; // 数据中心占用的位数
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// 每部分的最大值
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private static final long MAX_SEQUENCE = ~(-1L << SEQUENCE_BIT);
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private static final long MAX_MACHINE_NUM = ~(-1L << MACHINE_BIT);
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private static final long MAX_DATACENTER_NUM = ~(-1L << DATACENTER_BIT);
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// 每部分向左的位移
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private static final long MACHINE_LEFT = SEQUENCE_BIT;
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private static final long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
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private static final long TIMESTAMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;
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private static long datacenterId = 1; // 数据中心ID
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private static long machineId = 1; // 机器ID
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private static long sequence = 0L; // 序列号
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private static long lastTimestamp = -1L; // 上一次时间戳
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private SnowflakeIdGenerator() {}
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/**
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* 生成唯一ID
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*/
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public static synchronized long generateId() {
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long currTimestamp = getCurrentTimestamp();
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if (currTimestamp < lastTimestamp) {
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throw new RuntimeException("时钟回拨，拒绝生成ID");
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}
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if (currTimestamp == lastTimestamp) {
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// 相同毫秒内，序列号自增
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sequence = (sequence + 1) & MAX_SEQUENCE;
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// 同一毫秒的序列数已经达到最大
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if (sequence == 0L) {
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currTimestamp = getNextTimestamp();
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}
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} else {
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// 不同毫秒内，序列号置为0
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sequence = 0L;
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}
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lastTimestamp = currTimestamp;
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return (currTimestamp - START_TIMESTAMP) << TIMESTAMP_LEFT // 时间戳部分
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| datacenterId << DATACENTER_LEFT // 数据中心部分
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| machineId << MACHINE_LEFT // 机器标识部分
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| sequence; // 序列号部分
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}
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/**
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* 获取当前时间戳
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*/
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private static long getCurrentTimestamp() {
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return System.currentTimeMillis();
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}
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/**
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* 获取下一个时间戳
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*/
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private static long getNextTimestamp() {
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long timestamp = getCurrentTimestamp();
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while (timestamp <= lastTimestamp) {
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timestamp = getCurrentTimestamp();
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}
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return timestamp;
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}
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/**
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* 设置数据中心ID和机器ID
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*/
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public static void setWorker(long datacenterId, long machineId) {
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if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) {
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throw new IllegalArgumentException("datacenterId 不能大于 " + MAX_DATACENTER_NUM + " 或小于 0");
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}
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if (machineId > MAX_MACHINE_NUM || machineId < 0) {
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throw new IllegalArgumentException("machineId 不能大于 " + MAX_MACHINE_NUM + " 或小于 0");
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}
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SnowflakeIdGenerator.datacenterId = datacenterId;
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SnowflakeIdGenerator.machineId = machineId;
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}
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}
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