Java分布式唯一ID生成方案——比UUID效率更高的生成id工具类

package com.xinyartech.erp.core.util; import java.lang.management.ManagementFactory; import java.net.InetAddress; import java.net.NetworkInterface; import java.util.HashSet; import java.util.Set; /** * <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> * 核心代码为其IdWorker这个类实现，其原理结构如下，我分别用一个0表示一位，用—分割开部分的作用： * 1||0---0000000000 0000000000 0000000000 0000000000 0 --- 00000 ---00000 ---000000000000 * 在上面的字符串中，第一位为未使用（实际上也可作为long的符号位），接下来的41位为毫秒级时间， * 然后5位datacenter标识位，5位机器ID（并不算标识符，实际是为线程标识）， * 然后12位该毫秒内的当前毫秒内的计数，加起来刚好64位，为一个Long型。 * 这样的好处是，整体上按照时间自增排序，并且整个分布式系统内不会产生ID碰撞（由datacenter和机器ID作区分）， * 并且效率较高，经测试，snowflake每秒能够产生26万ID左右，完全满足需要。 * <p> * 64位ID (42(毫秒)+5(机器ID)+5(业务编码)+12(重复累加)) * * @author Lynch */
public 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 = 1563954651588L; // 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 IdWorker(){ this.datacenterId = getDatacenterId(maxDatacenterId); this.workerId = getMaxWorkerId(datacenterId, maxWorkerId); } /** * @param workerId * 工作机器ID * @param datacenterId * 序列号 */
    public IdWorker(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(); } /** * <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; } public static void main(String[] args) { long start = System.currentTimeMillis(); IdWorker idWorker=new IdWorker(0,0); Set<Long> idSet = new HashSet<Long>(); for(int i=0;i<1000000;i++){ long nextId = idWorker.nextId(); idSet.add(nextId); //System.out.println(nextId);
 } System.out.println(System.currentTimeMillis() - start); System.out.println(idSet.size()); } }