根据时间与自定义前缀生成生产流水号

//startLetter为订单号前缀

public static String create(String startLetter, int size, int numSize) {

String orderNo = null;

Date nowDate = new Date();

Random random = new Random();

SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");

//生成两位大写字母

String keyArr = randomLetter(size);

String fourRandom = random.nextInt(9999) + "";

int randLength = fourRandom.length();

//numSize 位随机数，不足 numSize 位的补0

if (fourRandom.length() < numSize) {

for (int i = 1; i <= numSize - randLength; i++) {

fourRandom = '0' + fourRandom;

}

}

orderNo = startLetter + keyArr + sdf.format(nowDate) + fourRandom;

return orderNo;

}