计算两个日期之间相隔天数

package com.toy.utils;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

/**
 * 计算两个日期之间的天数
 * 
 * @author 枫茗丿love
 *
 */
public class CountDaysUtils {

    private static final int[] MONTH_DAYS = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

    public static int getBetweenDays(LocalDate startDate, LocalDate endDate) {
        String startDateStr = startDate.format(DateTimeFormatter.ofPattern("yyyy-MM-dd"));
        String endDateStr = endDate.format(DateTimeFormatter.ofPattern("yyyy-MM-dd"));
        String[] startDateStrs = startDateStr.split("-");
        String[] endDateStrs = endDateStr.split("-");
        int days = 0;
        int startYear = Integer.parseInt(startDateStrs[0]);
        int startMonth = Integer.parseInt(startDateStrs[1]);
        int startDay = Integer.parseInt(startDateStrs[2]);
        int endYear = Integer.parseInt(endDateStrs[0]);
        int endMonth = Integer.parseInt(endDateStrs[1]);
        int endDay = Integer.parseInt(endDateStrs[2]);
        if (endYear >= startYear) {
            if (endYear == startYear) {
                if (endMonth < startMonth) {
                    return -1;
                }
                if (endMonth == startMonth) {
                    if (endDay < startDay) {
                        return -1;
                    } else {
                        days = endDay - startDay;
                    }
                }
                if (endMonth > startMonth) {
                    days = endDay + MONTH_DAYS[startMonth - 1] - startDay;
                    for (int month = startMonth; month < endMonth - 1; month++) {
                        if (((startYear % 4 == 0 && startYear % 100 != 0) || startYear % 400 == 0) && month == 1) {
                            days += 29;
                        } else {
                            days += MONTH_DAYS[month];
                        }
                    }
                }
            } else {

                days = endDay;
                for (int month = 0; month < endMonth - 1; month++) {
                    if (((endYear % 4 == 0 && endYear % 100 != 0) || endYear % 400 == 0) && month == 1) {
                        days += 29;
                    } else {
                        days += MONTH_DAYS[month];
                    }
                }

                for (int year = startYear + 1; year < endYear; year++) {
                    if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
                        days += 366;
                    } else {
                        days += 365;
                    }
                }

                int days2 = startDay;
                for (int month = 0; month < startMonth - 1; month++) {
                    if (((startYear % 4 == 0 && startYear % 100 != 0) || startYear % 400 == 0) && month == 1) {
                        days2 += 29;
                    } else {
                        days2 += MONTH_DAYS[month];
                    }
                }
                if (((startYear % 4 == 0 && startYear % 100 != 0) || startYear % 400 == 0)) {
                    days2 = 366 - days2;
                } else {
                    days2 = 365 - days2;
                }
                days += days2;
            }
            return days;
        } else
            return -1;
    }
}