Java 根据年月日精确计算年龄

import java.text.SimpleDateFormat;  
import java.util.Calendar;  
import java.util.Date;  
  
/** 
 * Created by qing on 2017/3/28. 
 */  
public class AgeUtils {  
    // 根据年月日计算年龄,birthTimeString:"1994-11-14"  
    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;  
        int monthMinus = monthNow - selectMonth;  
        int dayMinus = dayNow - selectDay;  
  
        int age = yearMinus;// 先大致赋值  
        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;  
    }  
  
    // 根据时间戳计算年龄  
    public static int getAgeFromBirthTime(long birthTimeLong) {  
        Date date = new Date(birthTimeLong * 1000l);  
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");  
        String birthTimeString = format.format(date);  
        return getAgeFromBirthTime(birthTimeString);  
    }  
}  

精确到月：

/**
 * Created by admin on 2017/12/15.
 */

public String getAgeFromBirthTime(Date birthDay) {
     Calendar cal = Calendar.getInstance();
     // 得到当前时间的年、月、日
     int yearNow = cal.get(Calendar.YEAR);
     int monthNow = cal.get(Calendar.MONTH)+1;
     int dayNow = cal.get(Calendar.DATE);
     // 先截取到传入中的年、月、日
     cal.setTime(birthDay);
     int selectYear = cal.get(Calendar.YEAR);
     int selectMonth = cal.get(Calendar.MONTH) + 1;
     int selectDay = cal.get(Calendar.DAY_OF_MONTH);
     // 用当前年月日减去生日年月日
     int yearMinus = yearNow - selectYear;
     int monthMinus = monthNow - selectMonth;
     int dayMinus = dayNow - selectDay;
     String  ageToMonth= "1月";

     if (yearMinus > 0){
          ageToMonth = String.valueOf(yearMinus)+"岁";
     } else if (monthMinus > 0) {
          ageToMonth = String.valueOf(monthMinus)+"月";
     }
     return ageToMonth;
}

　　

public static void main(String[] args) {
        String dataOfBirth = "2017-10-28";
        String age = getAgeFromBirthTime(dataOfBirth);
        System.out.println("age:" + age);
    }

鸡肋：

public class TestAge {
    public static void main(String[] args) {
//        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        try {
            //此处是获得的年龄
            int age = getAge(parse("2015-12-5 00:00:00"));           //由出生日期获得年龄***
            System.out.println(age);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //出生日期字符串转化成Date对象
    public static Date parse(String strDate) throws ParseException {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        return sdf.parse(strDate);
    }

    //由出生日期获得年龄
    public  static int getAge(Date birthDay) throws Exception {
        Calendar cal = Calendar.getInstance();
        if (cal.before(birthDay)) {
            throw new IllegalArgumentException(
                    "The birthDay is before Now.It's unbelievable!");
        }
        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;
    }