public class Order {

private static int orderNum = 0001;

public static String getOrderNo(){

long No = 0;

SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");

String nowdate = sdf.format(new Date());

No = Long.parseLong(nowdate)*10000;//这里如果一天订单多的话可以用一万或更大

No+=getNo();

return getUserId()+No;

}

public static int getNo(){//返回当天的订单数+1

orderNum++;

return orderNum;

}

public static String getUserId(){

return "123";

}

public static String RandomStringId(){

UUID uuid = UUID.randomUUID();

return uuid.toString();

}

}

 

也可以user+随机数+流水号(流水号为全局递增变量)  服务器重启就生成新的随机数