【算法思路】生成验证码

        String datas = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        String result = "";
        for (int i = 0; i < 6; i++) {
            int r = (int) (Math.random() * datas.length());
//            int r = new Random().nextInt(datas.length());
            result += datas.charAt(r);
        }
        System.out.println(result);