生成UUID

package com.gemantic.report.tyc.utils;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

/**
 * @Auther: Wangtianming
 * @Date: 2021/9/25 21:11
 * @Description:
 */
public class UUIDUtil {
    /*----------------------------------------------------------------------
     *
     * 第1-8位（年月日时分秒）
     * 第8-13位（当前时间处理过的字段）
     * 第13+位（编号序列默认4位数，不够前置补零，超出4位数按实际序列定）
     * 实例：20200702174649999 序列为4位数
     * 实例：202007021746410000 序列超出4位数
     *
     * ---------------------------------------------------------------------

    /**
     *  ID编号
     */
    public static AtomicInteger orderId = new AtomicInteger();

    public static int getOrderNextId(){
        return orderId.incrementAndGet();
    }


    /**
     *  获取ID
     * @return
     */
    public synchronized Long getOrderCode(){
        //当前时间
        String localDate = LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyyMMddHHMMSS"));
        //微秒
        String LongmicTime = (getmicTime ()).toString ();
        //拼接
        String s = "";
        String format = String.format("%04d", getOrderNextId());
        s += localDate.substring (0, 10);
        s +=  LongmicTime.substring (13, 16);;
        s += format;
        return Long.valueOf(s);
    }


    /**
     *  处理当前时间的纳秒
     * @return
     */
    private static Long getmicTime() {
        Long cutime = System.currentTimeMillis() * 1000; // 微秒
        Long nanoTime = System.nanoTime(); // 纳秒
        return cutime + (nanoTime - nanoTime / 1000000 * 1000000) / 1000;
    }

    private UUIDUtil(){}

    private static UUIDUtil uuidUtil;

    public static UUIDUtil getInstance(){
        if(uuidUtil == null)
            uuidUtil = new UUIDUtil();
        return uuidUtil;
    }


    //并发测试
    public static void main(String[] args) {

            List<Long> orderNos = Collections.synchronizedList(new ArrayList<Long>());
            IntStream.range(0,10000).parallel().forEach(i->{
                orderNos.add(UUIDUtil.getInstance().getOrderCode());
            });
            List<Long> filterOrderNos = orderNos.stream().distinct().collect(Collectors.toList());

            System.out.println("id数："+orderNos.size());
            System.out.println("过滤重复后id数："+filterOrderNos.size());
            System.out.println("重复id数："+(orderNos.size()-filterOrderNos.size()));

    }

}