/** * Created by youze on 18-7-5 */ public class IdWorker {
/** * 起始的时间戳 */ private final static long START_STMP = 1530795377086L;
/** * 每一部分占用的位数 */
/** * 序列号占用的位数 */ private final static long SEQUENCE_BIT = 12;
/** * 机器标识占用的位数 */ private final static long MACHINE_BIT = 5;
/** * 数据中心占用的位数 */ private final static long DATACENTER_BIT = 5;
/** * 每一部分的最大值 */ private final static long MAX_DATACENTER_NUM = -1L ^ (-1L << DATACENTER_BIT); private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT); private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);
/** * 每一部分向左的位移 */ private final static long MACHINE_LEFT = SEQUENCE_BIT; private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT; private final static long TIMESTMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;
/** * 数据中心 */ private long datacenterId;
/** * 机器标识 */ private long machineId; /** * 序列号 */ private long sequence = 0L;
/** * 上一次时间戳 */ private long lastStmp = -1L;
public IdWorker(long datacenterId, long machineId) { if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) { throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0"); } if (machineId > MAX_MACHINE_NUM || machineId < 0) { throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0"); } this.datacenterId = datacenterId; this.machineId = machineId; }
/** * 产生下一个ID * @return */ public synchronized long nextId() { long currStmp = getNewstmp(); if (currStmp < lastStmp) { throw new RuntimeException("Clock moved backwards. Refusing to generate id"); }