Java通过出生日期获取年龄的方法

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这个可以正常计算出年龄，会出现年龄负数，暂用待修正；

根据情况，参数不同参数即可；

不过我觉得在前端输入出生日期时，就应该对日期的选择进行限制。

/**
 * 分页查询
 */
    @Override
    public Page<Map> queryAllInfo(Long userId, Long relId, UserType userType, DoctorInfoDto d, Pageable pageable) {
            all = doctorInfoMapper.queryAllInfo(d, pageable);
            all.forEach(doc ->{
                calculateAge(doc);
            });
            enumService.transformEnum(all.getContent());
        }
        return all;
    }

    //通过生日日期计算年龄
    private void calculateAge(Map doc) {
        Object docBirthday = doc.get("birthday");
        if(docBirthday!=null){
            Calendar cal = Calendar.getInstance();

            if (cal.before((Date)docBirthday)) {
                throw new IllegalArgumentException(
                        "The birthDay is before Now.It's unbelievable!");
            }

            int yearNow = cal.get(Calendar.YEAR);
            int monthNow = cal.get(Calendar.MONTH) + 1;
            int dayOfMonthNow = cal.get(Calendar.DAY_OF_MONTH);

            cal.setTime((Date)docBirthday);
            int yearBirth = cal.get(Calendar.YEAR);
            int monthBirth = cal.get(Calendar.MONTH) + 1;
            int dayOfMonthBirth = cal.get(Calendar.DAY_OF_MONTH);

            int age = yearNow - yearBirth;

            if (monthNow <= monthBirth) {
                if (monthNow == monthBirth) {
                    // monthNow==monthBirth
                    if (dayOfMonthNow < dayOfMonthBirth) {
                        age--;
                    }
                } else {
                    // monthNow>monthBirth
                    age--;
                }
            }
            doc.put("age",age);
        }
    }