package com.gear.common.utils;

import java.security.SecureRandom;
import java.util.Random;

public class RandomGeneratorUtil {
    private static final String CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

    public static String generateRandomString(int length) {
        SecureRandom random = new SecureRandom();
        StringBuilder sb = new StringBuilder(length);

        for (int i = 0; i < length; i++) {
            int randomIndex = random.nextInt(CHARACTERS.length());
            sb.append(CHARACTERS.charAt(randomIndex));
        }
        return sb.toString();
    }
    public static String generateRandomNumber(int length) {
        if (length <= 0) {
            throw new IllegalArgumentException("Length must be greater than zero");
        }

        Random random = new Random();
        StringBuilder sb = new StringBuilder(length);

        // 生成首位不是0的随机数字
        sb.append(random.nextInt(9) + 1); // 首位数字范围在1到9之间

        // 生成剩余位数的随机数字
        for (int i = 1; i < length; i++) {
            sb.append(random.nextInt(10)); // 生成0到9之间的随机数字
        }

        return sb.toString();
    }
}