package com.gkhy.safePlatform.commons.utils.idService;
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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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import java.util.Date;
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import java.util.Enumeration;
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/**
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* @program: simple_tools
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* @description: 雪花算法代码实现
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**/
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public class SnowFlow {
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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） 2022-01-01 00:00:00
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private final static long twepoch = 1640966400000L;
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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 SnowFlow(){
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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 SnowFlow(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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//TODO 两段中心id，一段使用数据中心id，一段使用模块定义的常量
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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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NetworkInterface network = null;
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Enumeration<NetworkInterface> interfacts = NetworkInterface.getNetworkInterfaces();
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while (interfacts.hasMoreElements()){
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NetworkInterface networkInterface = interfacts.nextElement();
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Enumeration<InetAddress> inetss = networkInterface.getInetAddresses();
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while (inetss.hasMoreElements()){
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InetAddress inet = inetss.nextElement();
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if(inet.isLoopbackAddress())
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continue;
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if(inet.isSiteLocalAddress()){
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if(inet.getHostAddress().startsWith("192.168")){
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// System.out.println("IP : "+inet.getHostAddress());
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network = networkInterface;
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break;
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}
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}
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}
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}
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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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if(mac == null)
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System.out.println("MAC IS NULL");
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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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// e.printStackTrace();
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// System.out.println(" getDatacenterId: " + e.getMessage());
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System.out.println(" getDatacenterId: " + e.toString());
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}
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return id;
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}
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/* //测试
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public static void main(String[] args) {
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SnowFlow snowFlow = new SnowFlow();
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// for (int i = 0; i < 5; i++) {
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// System.out.println(snowFlow.nextId());
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// }
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System.out.println(snowFlow.nextId());
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}*/
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}
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