订单生成类，个人经验总结！

import java.sql.Timestamp;
import java.util.Random;

public class OrderIdBuilder {
    public static String createOrderId(){
        Random ran = new Random();
        Timestamp t = new Timestamp(System.currentTimeMillis());
        String orderId = t.toString().replaceAll("-", "").replaceAll(":", "").replace('.', ' ').replaceAll(" ", "").trim();
        for(int i=0; i<5; i++){
            int data = ran.nextInt(10);
            orderId = orderId + data;
        }
        return orderId;
    }
}