字符串隨機生成工具類

package com.gblfy.util;

import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Random;

/**
 * 字符隨機生成類
 */
@Component
public class RandomStrUtil {
    /**
     * 隨機產生類型枚舉
     */
    public static enum TYPE {
        /**
         * 小字符型
         */
        LETTER,
        /**
         * 大寫字符型
         */
        CAPITAL,
        /**
         * 數字型
         */
        NUMBER,
        /**
         * 大+小字符 型
         */
        LETTER_CAPITAL,
        /**
         * 小字符+數字 型
         */
        LETTER_NUMBER,
        /**
         * 大寫字符+數字
         */
        CAPITAL_NUMBER,
        /**
         * 大+小字符+數字 型
         */
        LETTER_CAPITAL_NUMBER,
    }

    private static String[] lowercase = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o",
            "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};

    private static String[] capital = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P",
            "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"};

    private static String[] number = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "0"};

    /**
     * 靜態隨機數
     */
    private static Random random = new Random();

    /**
     * 獲取隨機組合碼
     *
     * @param num  位數
     * @param type 類型
     * @type <br>小寫字符型 LETTER,
     * <br>大寫字符型 CAPITAL,
     * <br>數字型 NUMBER,
     * <br>大+小字符型 LETTER_CAPITAL,
     * <br>小字符+數字 型 LETTER_NUMBER,
     * <br>大字符+數字 型 CAPITAL_NUMBER,
     * <br>大+小字符+數字 型 LETTER_CAPITAL_NUMBER,
     */
    public static String getRandom(int num, TYPE type) {
        ArrayList<String> temp = new ArrayList<String>();
        StringBuffer code = new StringBuffer();
        switch (type) {
            case LETTER:
                temp.addAll(Arrays.asList(lowercase));
                break;
            case CAPITAL:
                temp.addAll(Arrays.asList(capital));
                break;
            case NUMBER:
                temp.addAll(Arrays.asList(number));
                break;
            case LETTER_CAPITAL:
                temp.addAll(Arrays.asList(lowercase));
                temp.addAll(Arrays.asList(capital));
                break;
            case LETTER_NUMBER:
                temp.addAll(Arrays.asList(lowercase));
                temp.addAll(Arrays.asList(number));
                break;
            case CAPITAL_NUMBER:
                temp.addAll(Arrays.asList(capital));
                temp.addAll(Arrays.asList(number));
                break;
            case LETTER_CAPITAL_NUMBER:
                temp.addAll(Arrays.asList(lowercase));
                temp.addAll(Arrays.asList(capital));
                temp.addAll(Arrays.asList(number));
                break;
        }
        for (int i = 0; i < num; i++) {
            code.append(temp.get(random.nextInt(temp.size())));
        }
        return code.toString();
    }

    //測試
    public static void main(String[] args) {
        System.out.println(RandomStrUtil.getRandom(64, RandomStrUtil.TYPE.LETTER_CAPITAL));
    }
}