package com.taiping.test;

import java.text.SimpleDateFormat;

import java.util.Date;

import java.util.Random;

public class Test12 {

/**

* 生成永不重復的訂單號

* @param startLetter 訂單號開頭字符串

* @param size 訂單號中隨機的大寫字母個數

* @return

*/

public static String createOrderNo(String startLetter,int size){

String orderNo = null;

Date nowDate = new Date();

Random random = new Random();

SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");

//生成兩位大寫字母

String keyArr = randomLetter(size);

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

int randLength = fourRandom.length();

//四位隨機數，不足四位的補0

if(fourRandom.length()<4){//不足四位的隨機數補充0

for(int i=1; i<=4-randLength; i++){

fourRandom = '0' + fourRandom;

}

}

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

return orderNo;

}

/**

* 生成大寫字母

* @param size

* @return

*/

public static String randomLetter(int size){

String keyArr= "";

char key = 0;

boolean[] flag=new boolean[26]; //定義一個Boolean型數組，用來除去重復值

for(int i=0;i

Random rand=new Random();

int index;

do{

index=rand.nextInt(26); //隨機生成0-25的數字并賦值給index

}while(flag[index]); //判斷flag值是否為true,如果為true則重新為index賦值

key=(char) (index+65); //大寫字母的ASCII值為65-90，所以給index的值加上65，使其符合大寫字母的ASCII值區間

flag[index]=true; //讓對應的flag值為true

keyArr +=key;

}

return keyArr;

}

/**

* 測試

* @param args

*/

public static void main(String[] args) {

System.out.println(createOrderNo("ND",2));

// NSBP202102041552086341

}

}

標簽：java,String,永不,訂單號,SimpleDateFormat,Java,fourRandom,size

來源： https://www.cnblogs.com/sinosoft/p/14373070.html