/**<p>项目名:</p> * <p>包名: com.zdb.module.test</p> * <p>文件名:IdWorker.java</p> * <p>版本信息:</p> * <p>日期:2015-5-23-下午1:17:49</p> * Copyright (c) 2015singno公司-版权所有 */ package com.zdb.module.test; /**<p>名称:IdWorker.java</p> * <p>描述:分布式自增长ID</p> * <pre> * Twitter的 Snowflake JAVA实现方案 * </pre> * @author 鲍建明 * @date 2015-5-23 下午1:17:49 * @version 1.0.0 */ public class IdWorker { private final long workerId; private final static long twepoch = 1288834974657L; private long sequence = 0L; private final static long workerIdBits = 4L; public final static long maxWorkerId = -1L ^ -1L << workerIdBits; private final static long sequenceBits = 10L; private final static long workerIdShift = sequenceBits; private final static long timestampLeftShift = sequenceBits + workerIdBits; public final static long sequenceMask = -1L ^ -1L << sequenceBits; private long lastTimestamp = -1L; public IdWorker(final long workerId) { super(); if (workerId > this.maxWorkerId || workerId < 0) { throw new IllegalArgumentException(String.format( "worker Id can‘t be greater than %d or less than 0", this.maxWorkerId)); } this.workerId = workerId; } public synchronized long nextId() { long timestamp = this.timeGen(); if (this.lastTimestamp == timestamp) { this.sequence = (this.sequence + 1) & this.sequenceMask; if (this.sequence == 0) { System.out.println("###########" + sequenceMask); timestamp = this.tilNextMillis(this.lastTimestamp); } } else { this.sequence = 0; } if (timestamp < this.lastTimestamp) { try { throw new Exception( String.format( "Clock moved backwards. Refusing to generate id for %d milliseconds", this.lastTimestamp - timestamp)); } catch (Exception e) { e.printStackTrace(); } } this.lastTimestamp = timestamp; long nextId = ((timestamp - twepoch << timestampLeftShift)) | (this.workerId << this.workerIdShift) | (this.sequence); System.out.println("timestamp:" + timestamp + ",timestampLeftShift:" + timestampLeftShift + ",nextId:" + nextId + ",workerId:" + workerId + ",sequence:" + 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(); } public static void main(String[] args){ IdWorker worker2 = new IdWorker(2); System.out.println(worker2.nextId()); } }
时间: 2024-10-08 15:30:49