java单例模式自动生成编号

package com.css.util;

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

/**
 * Created by pc on 2017/4/18.
 */
public class PrimaryGenerater {
    private static PrimaryGenerater primaryGenerater = null;

    private PrimaryGenerater() {
    }

    /**
     * 取得PrimaryGenerater的单例实现
     *
     * @return
     */
    public static PrimaryGenerater getInstance() {
        if (primaryGenerater == null) {
            synchronized (PrimaryGenerater.class) {
                if (primaryGenerater == null) {
                    primaryGenerater = new PrimaryGenerater();
                }
            }
        }
        return primaryGenerater;
    }

    /**
     *  生成下一个编号
     * @param sno    传最大的编号，才能返回累加后的!
     * @param prefix 生成的编号前缀
     * @return
     */
    public synchronized String generaterNextNumber(String sno,String prefix) {
        String id = null;
        Date date = new Date();
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy");
        if (StringHelper.isEmpty(sno)) {
            sno = prefix+"2017000000";// 第一次初始化编号
        }
        DecimalFormat df = new DecimalFormat("000000");
        id = prefix+formatter.format(date)+ df.format(1 + Integer.parseInt(sno.substring(7, sno.length())));

        return id;
    }

    public static void main(String[] args) {
        System.out.println(getInstance().generaterNextNumber("","GHZ"));
    }
}