根据身份证号码获取年龄

public static int getAge(String idcard) throws Exception {
        String strDate = "";
        if(idcard.length() == 18){
            strDate = idcard.substring(6,14);
        }else if(idcard.length() == 15){
            strDate = "19" + idcard.substring(6,12);
        }else{
            throw new RuntimeException("身份证号码格式错误");
        }
        System.out.println(strDate);
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
        Date birthDay = sdf.parse(strDate);
        Calendar cal = Calendar.getInstance();

        int yearNow = cal.get(Calendar.YEAR);
        int monthNow = cal.get(Calendar.MONTH);
        int dayOfMonthNow = cal.get(Calendar.DAY_OF_MONTH);
        cal.setTime(birthDay);

        int yearBirth = cal.get(Calendar.YEAR);
        int monthBirth = cal.get(Calendar.MONTH);
        int dayOfMonthBirth = cal.get(Calendar.DAY_OF_MONTH);

        int age = yearNow - yearBirth;
        if (monthNow <= monthBirth) {
            if (monthNow == monthBirth) {
                if (dayOfMonthNow < dayOfMonthBirth) age--;
            }else{
                age--;
            }
        }
        return age;
    }