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@@ -0,0 +1,89 @@
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+package com.fs.utils;
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+
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+import java.util.HashMap;
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+import java.util.Map;
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+
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+public class TwelveDigitSnowflake {
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+ private final long START_TIMESTAMP = 1672502400000L;
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+ private final long MACHINE_BIT = 5;
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+ private final long SEQUENCE_BIT = 7;
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+ private final long TIMESTAMP_BIT = 30;
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+ private final long MAX_MACHINE_NUM = ~(-1L << MACHINE_BIT);
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+ private final long MAX_SEQUENCE = ~(-1L << SEQUENCE_BIT);
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+
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+ private final long MACHINE_LEFT = SEQUENCE_BIT;
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+ private final long TIMESTAMP_LEFT = SEQUENCE_BIT + MACHINE_BIT;
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+
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+ private long machineId;
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+ private long sequence = 0L;
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+ private long lastTimeStamp = -1L;
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+
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+ // 构造函数,传入机器ID
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+ public TwelveDigitSnowflake(long machineId) {
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+ if (machineId > MAX_MACHINE_NUM || machineId < 0) {
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+ throw new IllegalArgumentException("机器ID超出范围");
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+ }
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+ this.machineId = machineId;
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+ }
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+
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+ // 生成下一个ID
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+ public synchronized long nextId() {
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+ long currentTimeStamp = getCurrentTimeStamp();
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+
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+ // 处理时钟回拨
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+ if (currentTimeStamp < lastTimeStamp) {
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+ long offset = lastTimeStamp - currentTimeStamp;
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+ if (offset <= 5) {
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+ try {
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+ wait(offset);
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+ currentTimeStamp = getCurrentTimeStamp();
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+ } catch (InterruptedException e) {
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+ e.printStackTrace();
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+ }
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+ } else { // 超过5毫秒回拨,抛出异常
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+ throw new RuntimeException("时钟回拨异常,无法生成ID");
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+ }
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+ }
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+
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+ if (currentTimeStamp == lastTimeStamp) {
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+ sequence = (sequence + 1) & MAX_SEQUENCE;
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+ if (sequence == 0) {
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+ currentTimeStamp = getNextMill();
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+ }
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+ } else {
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+ sequence = 0L;
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+ }
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+
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+ lastTimeStamp = currentTimeStamp;
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+
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+ // 组合ID:时间戳 + 机器ID + 序列号
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+ long id = ((currentTimeStamp - START_TIMESTAMP) << TIMESTAMP_LEFT)
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+ | (machineId << MACHINE_LEFT)
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+ | sequence;
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+ return id;
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+ }
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+
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+ private long getNextMill() {
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+ long mill = getCurrentTimeStamp();
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+ while (mill <= lastTimeStamp) {
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+ mill = getCurrentTimeStamp();
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+ }
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+ return mill;
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+ }
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+
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+ private long getCurrentTimeStamp() {
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+ return System.currentTimeMillis();
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+ }
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+
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+ public static void main(String[] args) {
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+ TwelveDigitSnowflake snowflake = new TwelveDigitSnowflake(1);
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+ Map<String,Long> check=new HashMap<>();
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+ for (int i = 0; i < 10000000; i++) {
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+ long id = snowflake.nextId();
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+ if(check.containsKey(String.valueOf(id))){
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+ throw new RuntimeException("雪花ID重复啦!!!!!!!");
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+ }
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+ check.put(String.valueOf(id),0L);
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+ }
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+ }
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+}
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