Java randomString

    public static String randomString(int strLength) {
        Random rnd = ThreadLocalRandom.current();
        StringBuilder ret = new StringBuilder();
        for (int i = 0; i < strLength; i++) {
            boolean isChar = (rnd.nextInt(2) % 2 == 0);// 輸出字母還是數字
            if (isChar) { // 字符串
                int choice = rnd.nextInt(2) % 2 == 0 ? 65 : 97; // 取得大寫字母還是小寫字母
                ret.append((char) (choice + rnd.nextInt(26)));
            } else { // 數字
                ret.append(Integer.toString(rnd.nextInt(10)));
            }
        }
        return ret.toString();
    }