package com.gk.hotwork.doublePrevention.utils;
|
|
import java.lang.management.ManagementFactory;
|
import java.net.InetAddress;
|
import java.net.NetworkInterface;
|
|
/**
|
* @program: simple_tools
|
* @description: 雪花算法代码实现
|
**/
|
public class SnowFlow {
|
|
// 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
|
private final static long twepoch = 1640966400000L;
|
// 机器标识位数
|
private final static long workerIdBits = 5L;
|
// 数据中心标识位数
|
private final static long datacenterIdBits = 5L;
|
// 机器ID最大值
|
private final static long maxWorkerId = -1L ^ (-1L << workerIdBits);
|
// 数据中心ID最大值
|
private final static long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
|
// 毫秒内自增位
|
private final static long sequenceBits = 12L;
|
// 机器ID偏左移12位
|
private final static long workerIdShift = sequenceBits;
|
// 数据中心ID左移17位
|
private final static long datacenterIdShift = sequenceBits + workerIdBits;
|
// 时间毫秒左移22位
|
private final static long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
|
|
private final static long sequenceMask = -1L ^ (-1L << sequenceBits);
|
/* 上次生产id时间戳 */
|
private static long lastTimestamp = -1L;
|
// 0，并发控制
|
private long sequence = 0L;
|
|
private final long workerId;
|
// 数据标识id部分
|
private final long datacenterId;
|
|
public SnowFlow(){
|
this.datacenterId = getDatacenterId(maxDatacenterId);
|
this.workerId = getMaxWorkerId(datacenterId, maxWorkerId);
|
}
|
/**
|
* @param workerId
|
* 工作机器ID
|
* @param datacenterId
|
* 序列号
|
*/
|
public SnowFlow(long workerId, long datacenterId) {
|
if (workerId > maxWorkerId || workerId < 0) {
|
throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
|
}
|
if (datacenterId > maxDatacenterId || datacenterId < 0) {
|
throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
|
}
|
this.workerId = workerId;
|
this.datacenterId = datacenterId;
|
}
|
/**
|
* 获取下一个ID
|
*
|
* @return
|
*/
|
public synchronized long nextId() {
|
long timestamp = timeGen();
|
if (timestamp < lastTimestamp) {
|
throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
|
}
|
|
if (lastTimestamp == timestamp) {
|
// 当前毫秒内，则+1
|
sequence = (sequence + 1) & sequenceMask;
|
if (sequence == 0) {
|
// 当前毫秒内计数满了，则等待下一秒
|
timestamp = tilNextMillis(lastTimestamp);
|
}
|
} else {
|
sequence = 0L;
|
}
|
lastTimestamp = timestamp;
|
// ID偏移组合生成最终的ID，并返回ID
|
long nextId = ((timestamp - twepoch) << timestampLeftShift)
|
| (datacenterId << datacenterIdShift)
|
| (workerId << workerIdShift) | sequence;
|
|
return nextId;
|
}
|
|
private long tilNextMillis(final long lastTimestamp) {
|
long timestamp = this.timeGen();
|
while (timestamp <= lastTimestamp) {
|
timestamp = this.timeGen();
|
}
|
return timestamp;
|
}
|
|
private long timeGen() {
|
return System.currentTimeMillis();
|
}
|
|
//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
|
/**
|
* <p>
|
* 获取 maxWorkerId
|
* </p>
|
*/
|
protected static long getMaxWorkerId(long datacenterId, long maxWorkerId) {
|
StringBuffer mpid = new StringBuffer();
|
mpid.append(datacenterId);
|
String name = ManagementFactory.getRuntimeMXBean().getName();
|
if (!name.isEmpty()) {
|
/*
|
* GET jvmPid
|
*/
|
mpid.append(name.split("@")[0]);
|
}
|
/*
|
* MAC + PID 的 hashcode 获取16个低位
|
*/
|
return (mpid.toString().hashCode() & 0xffff) % (maxWorkerId + 1);
|
}
|
|
/**
|
* <p>
|
* 数据标识id部分
|
* </p>
|
*/
|
protected static long getDatacenterId(long maxDatacenterId) {
|
long id = 0L;
|
try {
|
InetAddress ip = InetAddress.getLocalHost();
|
NetworkInterface network = NetworkInterface.getByInetAddress(ip);
|
if (network == null) {
|
id = 1L;
|
} else {
|
byte[] mac = network.getHardwareAddress();
|
id = ((0x000000FF & (long) mac[mac.length - 1])
|
| (0x0000FF00 & (((long) mac[mac.length - 2]) << 8))) >> 6;
|
id = id % (maxDatacenterId + 1);
|
}
|
} catch (Exception e) {
|
System.out.println(" getDatacenterId: " + e.getMessage());
|
}
|
return id;
|
}
|
|
/* //测试
|
public static void main(String[] args) {
|
SnowFlow snowFlow = new SnowFlow();
|
// for (int i = 0; i < 5; i++) {
|
// System.out.println(snowFlow.nextId());
|
// }
|
System.out.println(snowFlow.nextId());
|
}*/
|
}
|
