1. package com.zym.testpoi.util;
    3. import java.util.Calendar;
    4. import java.util.Date;
    6. public class DateUtil {
    7.     public static int differentDays(Date date1, Date date2){
    8.         Calendar calendar1 = Calendar.getInstance();
    9.         calendar1.setTime(date1);
    10.         Calendar calendar2 = Calendar.getInstance();
    11.         calendar2.setTime(date2);
    13.         int day1 = calendar1.get(Calendar.DAY_OF_YEAR);
    14.         int day2 = calendar2.get(Calendar.DAY_OF_YEAR);
    16.         int year1 = calendar1.get(Calendar.YEAR);
    17.         int year2 = calendar2.get(Calendar.YEAR);
    19.         if (year1 != year2){
    20.             int timeDistance = 0;
    21.             for (int i = year1;i<year2;i++){
    22.                 if (i%4 == 0 && i%100!=0 || i%400 == 0){ //闰年
    23.                     timeDistance += 366;
    24.                 }else{
    25.                     timeDistance += 365;
    26.                 }
    27.             }
    28.             return timeDistance + (day2 - day1);
    29.         }else {
    30.             return day2 - day1;
    31.         }
    32.     }
    33. }

    测试类：

    1. @Test
    2.     public void checkDifferentDays() throws ParseException {
    3.         String paramDate = "2020-09-20 10:00:00";
    4.         SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    5.         Date date = simpleDateFormat.parse(paramDate);
    6.         int i = DateUtil.differentDays(new Date(),date);
    7.         System.out.println(i);
    8.     }