JAVA 根据身份证计算年龄

birthDate = idCard.substring(6,10)+"-"+idCard.substring(10,12)+"-"+idCard.substring(12,14)

public  static  int  getAgefromBirthTime(String birthTimeString){

    // 先截取到字符串中的年、月、日
    String strs[] = birthTimeString.trim().split("-");
    int selectYear = Integer.parseInt(strs[0]);
    int selectMonth = Integer.parseInt(strs[1]);
    int selectDay = Integer.parseInt(strs[2]);
    // 得到当前时间的年、月、日
    Calendar cal = Calendar.getInstance();
    int yearNow = cal.get(Calendar.YEAR);
    int monthNow = cal.get(Calendar.MONTH) + 1;
    int dayNow = cal.get(Calendar.DATE);

    // 用当前年月日减去生日年月日
    int yearMinus = yearNow - selectYear -1;
    int monthMinus = monthNow - selectMonth;
    int dayMinus = dayNow - selectDay;

    int age = yearMinus;
    if (yearMinus < 0) {// 选了未来的年份
        age = 0;
    } else if (yearMinus == 0) {// 同年的，要么为1，要么为0
        if (monthMinus < 0) {// 选了未来的月份
            age = 0;
        } else if (monthMinus == 0) {// 同月份的
            if (dayMinus < 0) {// 选了未来的日期
                age = 0;
            } else if (dayMinus >= 0) {
                age = 1;
            }
        } else if (monthMinus > 0) {
            age = 1;
        }
    } else if (yearMinus > 0) {
        if (monthMinus < 0) {// 当前月>生日月
        } else if (monthMinus == 0) {// 同月份的，再根据日期计算年龄
            if (dayMinus < 0) {
            } else if (dayMinus >= 0) {
                age = age + 1;
            }
        } else if (monthMinus > 0) {
            age = age + 1;
        }
    }
    return age;

}