这个 DateUtil.java 类，整理的是 Java 中常用的一些日期转换方法，我们在项目开发中经常会用到。本工具类目前是基于 jdk1.8 版本编写，后续会一直不断地迭代更新。

package com.general.utils;

import ccdmsp.premier.cloud.constant.AppConstants;
import ccdmsp.premier.cloud.enums.ResultCode;
import ccdmsp.premier.cloud.exception.ApplicationException;
import org.apache.commons.lang3.time.DateUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.StringUtils;

import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;

/**
 * @author 易網°情深″
 * @discription 日期操作工具类
 * @create: 2020/03/22 17:55
 */
public final class DateUtil {
    private static final Logger LOGGER = LoggerFactory.getLogger(DateUtil.class);

    public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";

    public static final String DATE_FORMAT_YYYYMMDD = "yyyy-MM-dd";

    public static final String DATE_FORMAT_YYYYMMDD1 = "yyyy/MM/dd";

    public static final String DATE_FORMAT_YYYYMM = "yyyy-MM";

    public static final String DATE_FORMAT_YYYYMMDDHHMMSS = "yyyyMMddHHmmsssss";

    private static final Integer MAX_MONTH = 12;

    private DateUtil() {
        throw new UnsupportedOperationException("Util class");
    }

    /**
     * 获取当前时间
     *
     * @return
     */
    public static Date getNowDate() {
        Calendar calendar = Calendar.getInstance();
        return calendar.getTime();
    }

    /**
     * 获取指定日期月份的最后一天
     *
     * @param date
     * @return
     */
    public static Date getEndDateByMonth(Date date) {
        Date firstDate = null;
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH));
        cal.set(Calendar.HOUR_OF_DAY, 23);
        cal.set(Calendar.MINUTE, 59);
        cal.set(Calendar.SECOND, 59);
        firstDate = cal.getTime();
        return firstDate;
    }

    /**
     * 获取日期的月份
     *
     * @param date
     * @return
     */
    public static int getMonthByDate(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        return cal.get(Calendar.MONTH) + 1;
    }

    /**
     * 格式化时间为年月日
     *
     * @param date
     * @return
     */
    public static String toYMDString(Date date) {
        if (null != date) {
            return new SimpleDateFormat(DATE_FORMAT_YYYYMMDD).format(date);
        } else {
            return null;
        }
    }

    /**
     * 格式化时间为年月日时分秒
     *
     * @param date
     * @return
     */
    public static String toYMDHSString(Date date) {
        if (null != date) {
            return new SimpleDateFormat(DEFAULT_DATE_FORMAT).format(date);
        } else {
            return null;
        }
    }

    /**
     * 获取月份集合
     *
     * @return
     */
    public static List<Integer> getMonthList() {
        List<Integer> monthList = new ArrayList<>();
        for (int i = 1; i <= MAX_MONTH; i++) {
            monthList.add(i);
        }
        return monthList;
    }

    /**
     * 格式化日期为 Date 类型默认年月日时分秒
     *
     * @param dateStr
     * @return
     */
    public static Date parseDateYMD(String dateStr) {
        return parse(dateStr, DATE_FORMAT_YYYYMMDD);
    }

    public static Date parseDateYMD1(String dateStr) {
        return parse(dateStr, DATE_FORMAT_YYYYMMDD1);
    }

    public static Date parseDateYM(String dateStr) {
        return parse(dateStr, DATE_FORMAT_YYYYMM);
    }

    public static String toYMDHMSSString() {
        return new SimpleDateFormat(DATE_FORMAT_YYYYMMDDHHMMSS).format(getNowDate());
    }

    /**
     * 格式化日期为 Date 类型默认年月日
     *
     * @param dateStr
     * @return
     */
    public static Date parseDate(String dateStr) {
        return parse(dateStr, DEFAULT_DATE_FORMAT);
    }

    private static Date parse(String yearMonth, String dateFormat) {
        Date date = null;
        try {
            date = new SimpleDateFormat(dateFormat).parse(yearMonth);
        } catch (Exception pe) {
            LOGGER.error("Date call error", pe);
        }
        return date;
    }

    /**
     * 日期增加月
     *
     * @param date
     * @param iMonth
     * @return
     */
    public static Date addMonth(Date date, int iMonth) {
        return addDate(date, Calendar.MONTH, iMonth);
    }

    /**
     * 日期增加天数
     */
    public static Date addDay(Date date, int iDate) {
        return addDate(date, Calendar.DAY_OF_MONTH, iDate);
    }

    private static Date addDate(Date date, int iArg0, int iDate) {
        Calendar canlendar = Calendar.getInstance();
        canlendar.setTime(date);
        canlendar.add(iArg0, iDate);
        return canlendar.getTime();
    }

    public static Date addYear(Date date, int iYear) {
        return addDate(date, Calendar.YEAR, iYear);
    }

    /**
     * 日期增加秒
     */
    public static Date addSecond(Date date, int iDate) {
        return addDate(date, Calendar.SECOND, iDate);
    }

    /**
     * 日期增加分钟
     */
    public static Date addMinute(Date date, int iDate) {
        return addDate(date, Calendar.MINUTE, iDate);
    }

    /**
     * 根据日期获取所属季度
     *
     * @param date
     * @return
     */
    public static int getQuarter(Date date) {
        int season = -1;
        Calendar c = toCalendar(date);
        if (null != c) {
            //取值月份值(注:该值非真正的月份只是在 Calendar 中对应的月份真正值)
            int myMonth = c.get(Calendar.MONTH);
            switch (myMonth) {
                case Calendar.JANUARY:
                case Calendar.FEBRUARY:
                case Calendar.MARCH:
                    season = 1;
                    break;
                case Calendar.APRIL:
                case Calendar.MAY:
                case Calendar.JUNE:
                    season = 2;
                    break;
                case Calendar.JULY:
                case Calendar.AUGUST:
                case Calendar.SEPTEMBER:
                    season = 3;
                    break;
                case Calendar.OCTOBER:
                case Calendar.NOVEMBER:
                case Calendar.DECEMBER:
                    season = 4;
                    break;
                default:
                    break;
            }
        }
        return season;
    }

    private static Calendar toCalendar(Date date) {
        Calendar c = null;
        if (null != date) {
            c = Calendar.getInstance();
            c.setTime(date);
        }
        return c;
    }

    /**
     * 获取指定日期的年份，若为 null，则返回当前时间的年份
     *
     * @param date
     * @return
     */
    public static int getYear(Date date) {
        Calendar cal = Calendar.getInstance();
        if (!Objects.isNull(date)) {
            cal.setTime(date);
        }
        return cal.get(Calendar.YEAR);
    }

    /**
     * 获取当前时间的小时
     *
     * @return
     */
    public static int getHour() {
        Date date = getNowDate();
        Calendar cal = Calendar.getInstance();
        if (!Objects.isNull(date)) {
            cal.setTime(date);
        }
        return cal.get(Calendar.HOUR_OF_DAY);
    }

    /**
     * 两日期比较，若某值为 null，则取当前时间
     *
     * @param souceDate
     * @param targetDate
     * @return
     */
    public static Integer compareDate(Date souceDate, Date targetDate) {
        if (null == souceDate || null == targetDate) {
            return null;
        }
        return souceDate.compareTo(targetDate);
    }

    /**
     * 获取指定日期之间的所有月份第一天
     *
     * @param startDate
     * @param endDate
     * @return
     */
    public static List<Date> getMonthBetween(Date startDate, Date endDate) {
        ArrayList<Date> result = new ArrayList<>();
        Calendar min = Calendar.getInstance();
        Calendar max = Calendar.getInstance();
        min.setTime(startDate);
        min.set(min.get(Calendar.YEAR), min.get(Calendar.MONTH), 1);
        max.setTime(endDate);
        max.set(max.get(Calendar.YEAR), max.get(Calendar.MONTH), 2);
        Calendar curr = min;
        while (curr.before(max)) {
            result.add(curr.getTime());
            curr.add(Calendar.MONTH, 1);
        }
        return result;
    }

    /**
     * 将传过来的日期以 key-value 形式返回
     *
     * @param startDate
     * @param endDate
     * @return
     */
    private static Map<Date, Date> getStartAndEndDateMap(Date startDate, Date endDate) {
        Map<Date, Date> dateMap = new HashMap<>(2);
        dateMap.put(startDate, endDate);
        return dateMap;
    }

    /**
     * 将制定日期 + 指定天数
     */
    public static Date getDateAddNum(Date date, Integer num) {
        date = DateUtil.parseDateYMD(DateUtil.toYMDString(date));
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        c.add(Calendar.DAY_OF_MONTH, +num);
        return c.getTime();
    }

    /**
     * 通过时间秒毫秒数判断两个时间的间隔+1天
     *
     * @param date1
     * @param date2
     * @return
     */
    public static Integer daysBetween(Date date1, Date date2) {
        long difference = (date1.getTime() - date2.getTime()) / 86400000;
        return (int) Math.abs(difference) + 1;
    }

    /**
     * 获取当前天的0点，精确到毫秒
     *
     * @return
     */
    public static Date getNowDateInit() {
        Calendar calendar1 = Calendar.getInstance();
        calendar1.set(calendar1.get(Calendar.YEAR), calendar1.get(Calendar.MONTH), calendar1.get(Calendar.DAY_OF_MONTH),
                0, 0, 0);
        return parseDate(DateUtil.toYMDHSString(calendar1.getTime()));
    }

    /**
     * 获取今天最后的时间：当天23:59:59
     *
     * @return
     */
    public static Date getDayLastDate() {
        return addSecond(addDay(getNowDateInit(), 1), -1);
    }

    /**
     * 得到两个日期毫秒级差
     *
     * @param date0
     * @param date1
     * @return
     */
    public static long getMillisecondDif(Date date0, Date date1) {
        if (date0 == null || date1 == null) {
            return 0;
        }
        return date0.getTime() - date1.getTime();
    }

    /**
     * 得到两个日期秒级差
     *
     * @param date0
     * @param date1
     * @return
     */
    public static long getSecondDif(Date date0, Date date1) {
        return DateUtil.getMillisecondDif(date0, date1) / 1000;
    }

    /**
     * 得到两个日期分钟差
     *
     * @param date0
     * @param date1
     * @return
     */
    public static long getMinuteDif(Date date0, Date date1) {
        return DateUtil.getSecondDif(date0, date1) / 60;
    }

    /**
     * 得到两个日期小时差
     *
     * @param date0
     * @param date1
     * @return
     */
    public static int getHourDif(Date date0, Date date1) {
        return (int) DateUtil.getMinuteDif(date0, date1) / 60;
    }

    /**
     * 根据日期获取指定日期的0点
     *
     * @param date
     * @return
     */
    public static Date initDateByDay(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH),
                0, 0, 0);
        return calendar.getTime();
    }

    /**
     * 默认统计时间，转换成日期格式
     *
     * @return
     */
    public static String countYesterday(String countDate, int num) {
        if (StringUtils.isEmpty(countDate) || AppConstants.DEFAULT_DATE.equalsIgnoreCase(countDate)) {
            countDate = toYMDString(addDay(initDateByDay(getNowDate()), num));
        } else {
            if (!validFormatter(countDate, DATE_FORMAT_YYYYMMDD)) {
                throw new ApplicationException(ResultCode.DATE_FORMATTER_ERROR);
            }
        }
        return countDate;
    }

    /**
     * 验证日期类型
     *
     * @param date
     * @param format
     * @return
     */
    public static boolean validFormatter(String date, String format) {
        boolean flag = false;
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern(format);
        try {
            LocalDate.parse(date, formatter);
            flag = true;
        } catch (DateTimeParseException | NullPointerException e) {
            LOGGER.error("date Formatter is error");
        }
        return flag;
    }

    /**
     * 积分按季度清空接口使用，返回下个季度初的第一个日期，截至日，时、分、秒是零
     *
     * @param localDate
     * @return
     */
    public static Date getQuarterDuration(LocalDate localDate) {
        Calendar calendar = Calendar.getInstance();

        switch (localDate.getMonth().firstMonthOfQuarter().getValue()) {
            case 1:
                calendar.set(localDate.getYear(), 3, 1);
                break;
            case 4:
                calendar.set(localDate.getYear(), 6, 1);
                break;
            case 7:
                calendar.set(localDate.getYear(), 9, 1);
                break;
            case 10:
                calendar.set(localDate.plusYears(1).getYear(), 0, 1);
                break;
            default:
                break;
        }
        return DateUtils.truncate(calendar.getTime(), Calendar.DATE);
    }

    /**
     * 将日期格式化成中文的 “年+月+日+时”
     * <p>
     * 2020-01-01 15:00:00 → 2020年1月1日15时
     *
     * @param date
     * @return
     */
    public static String convertDateWithChinese(Date date) {
        String dateStr = toYMDHSString(date);
        return dateStr.substring(0, 4) + "年" +
                (dateStr.substring(5, 7).startsWith("0") ?
                        dateStr.substring(5, 7).replace("0", "")
                        : dateStr.substring(5, 7)) + "月" +
                (dateStr.substring(8, 10).startsWith("0") ?
                        dateStr.substring(8, 10).replace("0", "")
                        : dateStr.substring(8, 10)) + "日" +
                (dateStr.substring(11, 13).startsWith("0") ?
                        dateStr.substring(11, 13).replace("0", "")
                        : dateStr.substring(11, 13)) + "时";
    }
}