单例模式生成订单编号

package com.jeeplus.modules.biz.util;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;

/**
 * 单例模式
 * 生成订单编号
 */
public class SingletonUtil {
    private volatile static  SingletonUtil singletonUtil;
    private SingletonUtil(){}
    public static SingletonUtil getSingletonUtil(){
        if (singletonUtil == null){
            synchronized (SingletonUtil.class){
                if(singletonUtil==null){
                    singletonUtil = new SingletonUtil();
                }
            }
        }
        return singletonUtil;
    }

    /**
     * 生成编号
     * @param prefix
     * @return
     */
    public String makeOrderNum(String prefix){
        SimpleDateFormat simpleDateFormat;
        simpleDateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
        Date date = new Date();
        String str =prefix + "-" + simpleDateFormat.format(date);
        Random random = new Random();
        int ranNum = (int) (random.nextDouble() * (99999 - 10000 + 1)) + 10000;// 获取5位随机数
        System.out.println("生成订单号："+str + ranNum);
        return str + ranNum;// 当前时间
    }

    /**
     * 测试
     * @param args
     */
    public static void main(String[] args) {
        // 测试多线程调用订单号生成工具
        try {
            for (int i = 0; i < 100; i++) {
                Thread t1 = new Thread(new Runnable() {
                    public void run() {
                        SingletonUtil makeOrder = new SingletonUtil();
                        String prefix="HD";
                        makeOrder.makeOrderNum(prefix);
                    }
                }, "at" + i);
                t1.start();

                Thread t2 = new Thread(new Runnable() {
                    public void run() {
                        SingletonUtil makeOrder = new SingletonUtil();
                        String prefix="AB";
                        makeOrder.makeOrderNum(prefix);
                    }
                }, "bt" + i);
                t2.start();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}