生成指定长度的随机字符串

    /**
     * 随机产生一个length长度的a-Z和0-9混合字符串
     *
     * @param length 长度
     * @return 随机字符串
     */
    public static String generateRandomStr(int length) {
        String base = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        Random random = new Random();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++) {
            int number = random.nextInt(base.length());
            sb.append(base.charAt(number));
        }
        return sb.toString();
    }