随机码生成方法

1生成4位随机码,添加后缀.

    private static String random4Num() {
        int random = (int) ((Math.random() * 9 + 1) * 1000);
        return String.valueOf(random);
    }

2生成6位随机验证码

    private static String random6Num() {
        int random = (int) ((Math.random() * 9 + 1) * 100000);
        return String.valueOf(random);
    }