工具类:
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package com.ihrm.common.utils;
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import java.lang.management.ManagementFactory;
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import java.net.InetAddress;
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import java.net.NetworkInterface;
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//雪花算法代码实现
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public
class IdWorker {
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// 时间起始标记点，作为基准，一般取系统的最近时间（一旦确定不能变动）
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private
final
static
long twepoch =
1288834974657L;
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// 机器标识位数
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private
final
static
long workerIdBits =
5L;
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// 数据中心标识位数
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private
final
static
long datacenterIdBits =
5L;
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// 机器ID最大值
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private
final
static
long maxWorkerId = -
1L ^ (-
1L << workerIdBits);
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// 数据中心ID最大值
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private
final
static
long maxDatacenterId = -
1L ^ (-
1L << datacenterIdBits);
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// 毫秒内自增位
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private
final
static
long sequenceBits =
12L;
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// 机器ID偏左移12位
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private
final
static
long workerIdShift = sequenceBits;
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// 数据中心ID左移17位
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private
final
static
long datacenterIdShift = sequenceBits + workerIdBits;
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// 时间毫秒左移22位
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private
final
static
long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
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private
final
static
long sequenceMask = -
1L ^ (-
1L << sequenceBits);
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/* 上次生产id时间戳 */
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private
static
long lastTimestamp = -
1L;
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// 0，并发控制
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private
long sequence =
0L;
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private
final
long workerId;
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// 数据标识id部分
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private
final
long datacenterId;
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public IdWorker(){
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this.datacenterId = getDatacenterId(maxDatacenterId);
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this.workerId = getMaxWorkerId(datacenterId, maxWorkerId);
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}
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/**
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* @param workerId
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* 工作机器ID
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* @param datacenterId
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* 序列号
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*/
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public IdWorker(long workerId, long datacenterId) {
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if (workerId > maxWorkerId || workerId <
0) {
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throw
new IllegalArgumentException(String.format(
"worker Id can't be greater than %d or less than 0", maxWorkerId));
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}
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if (datacenterId > maxDatacenterId || datacenterId <
0) {
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throw
new IllegalArgumentException(String.format(
"datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
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}
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this.workerId = workerId;
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this.datacenterId = datacenterId;
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}
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/**
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* 获取下一个ID
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*
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* @return
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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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throw
new RuntimeException(String.format(
"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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// 当前毫秒内，则+1
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sequence = (sequence +
1) & sequenceMask;
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if (sequence ==
0) {
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// 当前毫秒内计数满了，则等待下一秒
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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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// ID偏移组合生成最终的ID，并返回ID
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long nextId = ((timestamp - twepoch) << timestampLeftShift)
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| (datacenterId << datacenterIdShift)
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| (workerId << workerIdShift) | sequence;
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return nextId;
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}
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private long tilNextMillis(final long lastTimestamp) {
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long timestamp =
this.timeGen();
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while (timestamp <= lastTimestamp) {
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timestamp =
this.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();
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}
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/**
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* <p>
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* 获取 maxWorkerId
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* </p>
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*/
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protected static long getMaxWorkerId(long datacenterId, long maxWorkerId) {
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StringBuffer mpid =
new StringBuffer();
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mpid.append(datacenterId);
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String name = ManagementFactory.getRuntimeMXBean().getName();
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if (!name.isEmpty()) {
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/*
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* GET jvmPid
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*/
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mpid.append(name.split(
"@")[
0]);
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}
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/*
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* MAC + PID 的 hashcode 获取16个低位
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*/
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return (mpid.toString().hashCode() &
0xffff) % (maxWorkerId +
1);
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}
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/**
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* <p>
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* 数据标识id部分
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* </p>
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*/
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protected static long getDatacenterId(long maxDatacenterId) {
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long id =
0L;
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try {
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InetAddress ip = InetAddress.getLocalHost();
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NetworkInterface network = NetworkInterface.getByInetAddress(ip);
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if (network ==
null) {
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id =
1L;
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}
else {
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byte[] mac = network.getHardwareAddress();
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id = ((
0x000000FF & (
long) mac[mac.length -
1])
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| (
0x0000FF00 & (((
long) mac[mac.length -
2]) <<
8))) >>
6;
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id = id % (maxDatacenterId +
1);
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}
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}
catch (Exception e) {
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System.out.println(
" getDatacenterId: " + e.getMessage());
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}
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return id;
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}
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}
使用:
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IdWorker idWorker =
new IdWorker();
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long id = idWorker.nextId();
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