雪花算法生成ID（两套代码）

代码不是自己写的。 收集而来！

第一套

package com.utils; import java.lang.management.ManagementFactory; import java.net.InetAddress; import java.net.NetworkInterface; /** * @author 子诚 * Description：雪花算法生成唯一ID * 时间：2020/6/30 19:19 */ public final class IdWorker { /** * 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） */ private final static long TWEPOCH = 1288834974657L; /** * 机器标识位数 */ private final static long WORKER_ID_BITS = 5L; /** * 数据中心标识位数 */ private final static long DATA_CENTER_ID_BITS = 5L; /** * 机器ID最大值 */ private final static long MAX_WORKER_ID = ~(-1L << WORKER_ID_BITS); /** * 数据中心ID最大值 */ private final static long MAX_DATA_CENTER_ID = ~(-1L << DATA_CENTER_ID_BITS); /** * 毫秒内自增位 */ private final static long SEQUENCE_BITS = 12L; /** * 机器ID偏左移12位 */ private final static long WORKER_ID_SHIFT = SEQUENCE_BITS; /** * 数据中心ID左移17位 */ private final static long DATA_CENTER_ID_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS; /** * 时间毫秒左移22位 */ private final static long TIME_STAMP_LEFT_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS + DATA_CENTER_ID_BITS; private final static long SEQUENCE_MASK = ~(-1L << SEQUENCE_BITS); /** * 上次生产id时间戳 */ private static long LAST_TIME_STAMP = -1L; /** * 0，并发控制 */ private long sequence = 0L; private final long workerId; /** * 数据标识id部分 */ private final long DATA_CENTER_ID; public IdWorker() { this.DATA_CENTER_ID = getDatacenterId(MAX_DATA_CENTER_ID); this.workerId = getMaxWorkerId(DATA_CENTER_ID, MAX_WORKER_ID); } public IdWorker(long workerId, long datacenterId) { if (workerId > MAX_WORKER_ID || workerId < 0) { throw new IllegalArgumentException(String.format("id不能大于最大值 %d 或者小于 0", MAX_WORKER_ID)); } if (datacenterId > MAX_DATA_CENTER_ID || datacenterId < 0) { throw new IllegalArgumentException(String.format("数据中心id不能大于最大值 %d 或者小于 0", MAX_DATA_CENTER_ID)); } this.workerId = workerId; this.DATA_CENTER_ID = datacenterId; } /** * 获取下一个ID * * @return id */ public synchronized long nextId() { long timestamp = timeGen(); if (timestamp < LAST_TIME_STAMP) { throw new RuntimeException(String.format("时间生成异常 %d", LAST_TIME_STAMP - timestamp)); } if (LAST_TIME_STAMP == timestamp) { // 当前毫秒内，则+1 sequence = (sequence + 1) & SEQUENCE_MASK; if (sequence == 0) { // 当前毫秒内计数满了，则等待下一秒 timestamp = tilNextMillis(LAST_TIME_STAMP); } } else { sequence = 0L; } LAST_TIME_STAMP = timestamp; // ID偏移组合生成最终的ID，并返回ID return ((timestamp - TWEPOCH) << TIME_STAMP_LEFT_SHIFT) | (DATA_CENTER_ID << DATA_CENTER_ID_SHIFT) | (workerId << WORKER_ID_SHIFT) | sequence; } private long tilNextMillis(final long lastTimestamp) { long timestamp = this.timeGen(); while (timestamp <= lastTimestamp) { timestamp = this.timeGen(); } return timestamp; } private long timeGen() { return System.currentTimeMillis(); } /** * <p> * 获取 maxWorkerId * </p> */ private static long getMaxWorkerId(long dataCenterId, long maxWorkerId) { StringBuilder mpid = new StringBuilder(); 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> */ private 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; } /** * 静态工具类 * * @return id */ public static synchronized String generateId() { String id = String.valueOf(new IdWorker().nextId()); return id; } /** * 测试 */ public static void main(String[] args) { System.out.println("当前时间戳：" + System.currentTimeMillis()); for (int i = 0; i < 10; i++) { //生成唯一雪花id String id = IdWorker.generateId(); System.out.println("第" + i + "个：" + id + ";长度为：" + id.length()); } } }

第二套

package com.utils; import org.apache.commons.lang3.RandomUtils; import org.apache.commons.lang3.StringUtils; import org.apache.commons.lang3.SystemUtils; import java.net.Inet4Address; import java.net.UnknownHostException; /** * @author 子诚 * Description：雪花算法生成唯一ID * 时间：2020/6/30 19:19 */ public class SnowflakeIdWorker { // ==============================Fields=========================================== /** * 开始时间截 (2015-01-01) */ private final long twepoch = 1288834974657L; /** * 机器id所占的位数 */ private final long workerIdBits = 5L; /** * 数据标识id所占的位数 */ private final long dataCenterIdBits = 5L; /** * 支持的最大机器id，结果是31 (这个移位算法可以很快的计算出几位二进制数所能表示的最大十进制数) */ private final long maxWorkerId = -1L ^ (-1L << workerIdBits); /** * 支持的最大数据标识id，结果是31 */ private final long maxDataCenterId = -1L ^ (-1L << dataCenterIdBits); /** * 序列在id中占的位数 */ private final long sequenceBits = 12L; /** * 机器ID向左移12位 */ private final long workerIdShift = sequenceBits; /** * 数据标识id向左移17位(12+5) */ private final long dataCenterIdShift = sequenceBits + workerIdBits; /** * 时间截向左移22位(5+5+12) */ private final long timestampLeftShift = sequenceBits + workerIdBits + dataCenterIdBits; /** * 生成序列的掩码，这里为4095 (0b111111111111=0xfff=4095) */ private final long sequenceMask = -1L ^ (-1L << sequenceBits); /** * 工作机器ID(0~31) */ private long workerId; /** * 数据中心ID(0~31) */ private long dataCenterId; /** * 毫秒内序列(0~4095) */ private long sequence = 0L; /** * 上次生成ID的时间截 */ private long lastTimestamp = -1L; private static SnowflakeIdWorker idWorker; static { idWorker = new SnowflakeIdWorker(getWorkId(), getDataCenterId()); } //==============================Constructors===================================== /** * 构造函数 * * @param workerId 工作ID (0~31) * @param dataCenterId 数据中心ID (0~31) */ public SnowflakeIdWorker(long workerId, long dataCenterId) { if (workerId > maxWorkerId || workerId < 0) { throw new IllegalArgumentException(String.format("workerId can't be greater than %d or less than 0", maxWorkerId)); } if (dataCenterId > maxDataCenterId || dataCenterId < 0) { throw new IllegalArgumentException(String.format("dataCenterId can't be greater than %d or less than 0", maxDataCenterId)); } this.workerId = workerId; this.dataCenterId = dataCenterId; } // ==============================Methods========================================== /** * 获得下一个ID (该方法是线程安全的) * * @return SnowflakeId */ public synchronized long nextId() { long timestamp = timeGen(); //如果当前时间小于上一次ID生成的时间戳，说明系统时钟回退过这个时候应当抛出异常 if (timestamp < lastTimestamp) { throw new RuntimeException( String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp)); } //如果是同一时间生成的，则进行毫秒内序列 if (lastTimestamp == timestamp) { sequence = (sequence + 1) & sequenceMask; //毫秒内序列溢出 if (sequence == 0) { //阻塞到下一个毫秒,获得新的时间戳 timestamp = tilNextMillis(lastTimestamp); } } //时间戳改变，毫秒内序列重置 else { sequence = 0L; } //上次生成ID的时间截 lastTimestamp = timestamp; //移位并通过或运算拼到一起组成64位的ID return ((timestamp - twepoch) << timestampLeftShift) | (dataCenterId << dataCenterIdShift) | (workerId << workerIdShift) | sequence; } /** * 阻塞到下一个毫秒，直到获得新的时间戳 * * @param lastTimestamp 上次生成ID的时间截 * @return 当前时间戳 */ protected long tilNextMillis(long lastTimestamp) { long timestamp = timeGen(); while (timestamp <= lastTimestamp) { timestamp = timeGen(); } return timestamp; } /** * 返回以毫秒为单位的当前时间 * * @return 当前时间(毫秒) */ protected long timeGen() { return System.currentTimeMillis(); } private static Long getWorkId() { try { String hostAddress = Inet4Address.getLocalHost().getHostAddress(); int[] ints = StringUtils.toCodePoints(hostAddress); int sums = 0; for (int b : ints) { sums += b; } return (long) (sums % 32); } catch (UnknownHostException e) { // 如果获取失败，则使用随机数备用 return RandomUtils.nextLong(0, 31); } } private static Long getDataCenterId() { int[] ints = StringUtils.toCodePoints(SystemUtils.getHostName()); int sums = 0; for (int i : ints) { sums += i; } return (long) (sums % 32); } /** * 静态工具类 * * @return */ public static synchronized String generateId() { long longId = idWorker.nextId(); //转成字符串 String id = String.valueOf(longId); return id; } //==============================Test============================================= /** * 测试 */ public static void main(String[] args) { System.out.println(System.currentTimeMillis()); long startTime = System.nanoTime(); for (int i = 0; i < 100; i++) { //生成唯一雪花id String id = SnowflakeIdWorker.generateId(); System.out.println("第" + i + "个：" + id + ";长度为：" + id.length()); } System.out.println((System.nanoTime() - startTime) / 1000000 + "ms"); } }