java 日期工具类

package com.jd.rc.custom.oper.bff.common;

import com.jd.fastbe.framework.client.support.exception.BusinessException;
import com.jd.fastbe.framework.client.support.exception.DefaultErrorCodeEnum;
import org.apache.commons.lang3.StringUtils;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
 * 时间转换工具
 *
 * @author jialong12
 * @date 2021-10-14 21:57
 */
public class DateUtils {

    public static final String MM_dd = "MM-dd";
    public static final String HH_mm = "HH:mm";
    public static final String MM_dd2 = "MM/dd";
    private static final String yyyy_MM_dd = "yyyy-MM-dd";
    public static final String HH = "HH";
    public static final String YYYY_MM_DD = "yyyy-MM-dd";
    private static final String yyyy_MM_dd_HH_mm_ss = "yyyy-MM-dd HH:mm:ss";

    private static final String yyyy_MM_dd_HH = "yyyy-MM-dd HH";
    /**
     * 一天的毫秒
     */
    private static final long DAY_MILLS = 1000 * 24 * 3600;

    /**
     * 解析字符串时间为Date类型
     *
     * @param dateStr 时间
     * @return 时间
     */
    public static Date parse(String dateStr, String pattern) {
        if (StringUtils.isBlank(dateStr)) {
            return null;
        }
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        try {
            return sdf.parse(dateStr);
        } catch (Exception e) {
            throw new BusinessException(DefaultErrorCodeEnum.BAD_ARGUMENT_ERROR, "时间格式有误", e);
        }
    }

    /**
     * 转换时间为字符串格式
     *
     * @param date 时间
     * @return 时间
     */
    public static String format(Date date, String pattern) {
        if (date == null) {
            return null;
        }
        return new SimpleDateFormat(pattern).format(date);
    }

    public static Date parseDate(String dateStr) {
        return parse(dateStr, yyyy_MM_dd);
    }

    public static String formatDate(Date date) {
        return format(date, yyyy_MM_dd);
    }

    public static String formatDateTime(Date date) {
        return format(date, yyyy_MM_dd_HH_mm_ss);
    }

    public static String formatDateHH(Date date) {
        return format(date, yyyy_MM_dd_HH);
    }

    public static Date parseDateTime(String dateStr) {
        return parse(dateStr, yyyy_MM_dd_HH_mm_ss);
    }

    public static Date parseDateHH(String dateStr) {
        return parse(dateStr, yyyy_MM_dd_HH);
    }

    public static Date parseHH(String dateStr) {
        return parse(dateStr, HH);
    }

    /**
     * 结束时间大于等于开始时间
     */
    public static boolean dateGt(Date after, Date before) {
        return after.getTime() >= before.getTime();
    }

    /**
     * 时间设置为 23：59：59
     */
    public static Date setEndTime(Date date) {
        if (date == null) {
            return null;
        }

        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);

        calendar.set(Calendar.HOUR_OF_DAY, 23);
        calendar.set(Calendar.MINUTE, 59);
        calendar.set(Calendar.SECOND, 59);
        calendar.set(Calendar.MILLISECOND, 999);
        return calendar.getTime();
    }

    /**
     * 时间设置为 00：00：00
     */
    public static Date setStartTime(Date date) {
        if (date == null) {
            return null;
        }

        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);

        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return calendar.getTime();
    }

    /**
     * 时间后
     *
     * @param date 当前时间
     * @param days 如果为正数，则是多少天后，负数则为多少天前
     * @return 日期
     */
    public static Date after(Date date, int days) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);

        calendar.add(Calendar.DAY_OF_YEAR, days);

        return calendar.getTime();
    }


    /**
     * 计算相差天数
     *
     * @param before 之前时间
     * @param after  之后时间
     * @return 天数
     */
    public static int days(Date before, Date after) {
        // 天数
        return ((int) ((after.getTime() - setStartTime(before).getTime()) / DAY_MILLS));
    }

    public static void main(String[] args) {
        Date date = DateUtils.parseDate("2022-07-30");
        System.out.println(formatDate(after(date, -1)));
        System.out.println(formatDate(after(date, -1)));
        System.out.println(formatDate(after(date, -1)));
        System.out.println(formatDate(after(date, -1)));
    }

    //获取前、后month个月时间
    public static Date getDateBefore3Month(Date dNow, Integer month) {

        if (dNow == null) {
            return null;
        }

        Calendar calendar = Calendar.getInstance(); //得到日历
        calendar.setTime(dNow);//把当前时间赋给日历
        calendar.add(Calendar.MONTH, month);  //设置为前3月
        return calendar.getTime();   //得到前3月的时间
    }
}