根据身份证计算年龄逻辑不准确

[sunyaf]

假如生日是2008-07-11，当前时间2014-07-11，IdcardUtil.getAgeByIdCard 得出来是15岁 假如生日是2008-07-31，当前时间2014-07-31，IdcardUtil.getAgeByIdCard 得出来是16岁

为什么是这个逻辑呢

protected static int age(long birthday, long dateToCompare) {
        if (birthday > dateToCompare) {
            throw new IllegalArgumentException("Birthday is after dateToCompare!");
        } else {
            Calendar cal = Calendar.getInstance();
            cal.setTimeInMillis(dateToCompare);
            int year = cal.get(1);
            int month = cal.get(2);
            int dayOfMonth = cal.get(5);
            boolean isLastDayOfMonth = dayOfMonth == cal.getActualMaximum(5);
            cal.setTimeInMillis(birthday);
            int age = year - cal.get(1);
            int monthBirth = cal.get(2);
            if (age == 0) {
                return 0;
            } else {
                if (month == monthBirth) {
                    int dayOfMonthBirth = cal.get(5);
                    boolean isLastDayOfMonthBirth = dayOfMonthBirth == cal.getActualMaximum(5);
                    if ((!isLastDayOfMonth || !isLastDayOfMonthBirth) && dayOfMonth <= dayOfMonthBirth) {
                        --age;
                    }
                } else if (month < monthBirth) {
                    --age;
                }
                return age;
            }
        }
    }

[looly]

你是不使用了旧版本的Hutool导致的问题？

的出来的都是5岁。