java8以下 计算两个日期相差几年几月几天，考虑闰年平年

  //    java 计算两个日期相差几年几月几天，考虑闰年平年public void calculateDifference(String startDade, String endDate) {Calendar calendar1 = Calendar.getInstance(); // 第一个日期，默认当前日期Calendar calendar2 = Calendar.getInstance(); // 第二个日期，默认当前日期// 设置第一个日期的年、月、日calendar1.set(Calendar.YEAR, RexgUtil.getYMD(startDade)[0]);calendar1.set(Calendar.MONTH, RexgUtil.getYMD(startDade)[1]);calendar1.set(Calendar.DAY_OF_MONTH, RexgUtil.getYMD(startDade)[2]);if (null != endDate) {calendar2.set(Calendar.YEAR, RexgUtil.getYMD(endDate)[0]);calendar2.set(Calendar.MONTH, RexgUtil.getYMD(endDate)[1]);calendar2.set(Calendar.DAY_OF_MONTH, RexgUtil.getYMD(endDate)[2]);}int yearDifference = calendar2.get(Calendar.YEAR) - calendar1.get(Calendar.YEAR);int monthDifference = calendar2.get(Calendar.MONTH)+(null != endDate ? 0 : 1) - calendar1.get(Calendar.MONTH);int dayDifference = calendar2.get(Calendar.DAY_OF_MONTH) - calendar1.get(Calendar.DAY_OF_MONTH);// 考虑日期超出状况，需要从年或者月借位if (dayDifference < 0) {monthDifference -= 1;int month = calendar1.get(Calendar.MONTH);int year = calendar1.get(Calendar.YEAR);// 判断是否为2月，考虑闰年平年if (month == Calendar.FEBRUARY) {if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {dayDifference += 29;} else {dayDifference += 28;}} else if (month == Calendar.APRIL ||month == Calendar.JUNE ||month == Calendar.SEPTEMBER ||month == Calendar.NOVEMBER) {dayDifference += 30;} else {dayDifference += 31;}}if (yearDifference <= 0) {// 考虑闰年的情况if (monthDifference < 0 || (monthDifference == 0 && dayDifference < 0)) {yearDifference--;monthDifference += 12;}dayDifference = monthDifference <=0 ? (dayDifference+1) : dayDifference;}System.out.println("Years: " + yearDifference);System.out.println("Months: " + monthDifference);System.out.println("Days: " + dayDifference);}public class RexgUtil {public static int[] getYMD(String yyyymmddStr) {int[] ymd= new int[3];
//        String input = "2023年08月03日";// 使用正则表达式匹配年、月、日String pattern = "([0-9]{4})年([0-9]{2})月([0-9]{2})日";Pattern regex = Pattern.compile(pattern);Matcher matcher = regex.matcher(yyyymmddStr);if (matcher.find()) {String year = matcher.group(1);String month = matcher.group(2);String day = matcher.group(3);//            System.out.println("年: " + year);
//            System.out.println("月: " + month);
//            System.out.println("日: " + day);ymd[0] = Integer.parseInt(year);ymd[1] = Integer.parseInt(month);ymd[2] = Integer.parseInt(day);}return ymd;}
}

如：2015年1月9日至今相差

jdk8以上的代码更简洁：

import java.time.LocalDate;
import java.time.Period;
import java.time.temporal.ChronoUnit;public class Main {public static void main(String[] args) {//设置开始日期和结束日期LocalDate startDate = LocalDate.of(2010, 1, 1);LocalDate endDate = LocalDate.of(2020, 9, 20);//按整月计算差值long monthsBetween = ChronoUnit.MONTHS.between(startDate, endDate);long years = monthsBetween / 12;long remainMonths = monthsBetween % 12;//按天计算差值long daysBetween = ChronoUnit.DAYS.between(startDate.plusMonths(monthsBetween), endDate);System.out.println("相差" + years + "年" + remainMonths + "月" + daysBetween + "天");//或者你也可以使用Period做更精确的计算Period period = Period.between(startDate, endDate);System.out.println("相差" + period.getYears() + "年" + period.getMonths() + "月" + period.getDays() + "天");}
}