java实现验证码的功能

package com.ityx.d3_static_test;

import java.util.Random;


public class VerifyTool {
    //private VerifyTool(){}
    public static void main(String[] args) {
        System.out.println("验证码：" + createCode(5));
    }
    public static String createCode(int n){
        String chars = "abcdefghijklmnoqprstuvwxyzABCDEFGHIJKLMNOQPRSTUVWXYZ0123456789";
        String code = "";
        Random r = new Random();
        for(int i = 0;i