110 lines
3.4 KiB
Java
110 lines
3.4 KiB
Java
package com.zhgd.xmgl.config;
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/**
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* 0000000000 0 - 0000000000 0000000000 0000000000 0 - 00 0000000000 - 0000000000
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* 11位标识 - 31位时间戳 - 12位服务序列号 - 10位顺序位
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* 注：
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* 1.生成ID缩短至16位
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* 2.31位精确到秒时间戳可使用68年，生成16位ID时保证使用60.5年
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* 3.12位服务序列号，可以支持部署4096个节点
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* 4.10位顺序位，每秒生成1024个ID
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* <p>
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* 16位极值 对应时间戳（1365367696）（2013-04-08 04:48:16） 对应数据中心ID 对应顺序位
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* 最大值：9007199254740991 2147483647（2081-04-26 08:02:23） 4095 1023
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* 16位值：1000000000000000 238418579（2020-10-27 16:11:15） 416 0
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* 最小值： 4195329 1（2013-04-08 04:48:17） 1 1
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* <p>
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* 1111111111111111111111111111111 111111111111 1111111111
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* 0001110001101011111101010010011 000110100000 0000000000
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* 0000000000000000000000000000001 000000000001 0000000001
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*
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* @program: wisdomSite
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* @description:
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* @author: Mr.Peng
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* @create: 2021-12-16 18:19
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**/
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public class IDGenerator {
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/**
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* 服务序列号
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*/
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private long serviceSequence = 1L;
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/**
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* 时间戳开始计时时间 2013-04-08 04:48:16
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*/
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private final long startTimestamp = 1365367696L;
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/**
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* 默认顺序位的初始值
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*/
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private long sequence = 1L;
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/**
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* 顺序位2进制长度
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*/
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private final long sequenceBits = 10L;
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/**
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* 服务序列号2进制长度
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*/
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private final long serviceSequenceBits = 12L;
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/**
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* 服务序列号右移位数
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*/
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private final long serviceSequenceShift = sequenceBits;
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/**
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* 时间戳右移位数
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*/
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private final long timestampShift = sequenceBits + serviceSequenceBits;
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/**
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* 生成序列的掩码(10位所对应的最大整数值)，这里为1023 (0b1111111111=1023)
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*/
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private final long sequenceMask = -1L ^ (-1L << sequenceBits);
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private long lastTimestamp = -1L;
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public IDGenerator(Long serviceSequence) {
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this.serviceSequence = serviceSequence;
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}
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/**
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* 生成唯一的趋势递增的id
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*/
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public synchronized long nextId() {
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long timestamp = timeGen();
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if (timestamp < lastTimestamp) {
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System.err.printf("clock is moving backwards. Rejecting requests until %d.", lastTimestamp);
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throw new RuntimeException(String.format(
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"Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
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}
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if (lastTimestamp == timestamp) {
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sequence = (sequence + 1L) & sequenceMask;
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if (sequence == 0L) {
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timestamp = tilNextMillis(lastTimestamp);
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}
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} else {
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sequence = 0L;
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}
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lastTimestamp = timestamp;
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return ((timestamp - startTimestamp) << timestampShift) | (serviceSequence << serviceSequenceShift) | sequence;
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}
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private long tilNextMillis(long lastTimestamp) {
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long timestamp = timeGen();
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while (timestamp <= lastTimestamp) {
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timestamp = timeGen();
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}
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return timestamp;
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}
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private long timeGen() {
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return System.currentTimeMillis() / 1000L;
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}
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}
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