处理时间的工具类

import org.slf4j.LoggerFactory;

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

/**
 * Created by IntelliJ IDEA
 * 这是一个神奇的Class
 *
 * @author zhz
 * @date 2020/3/26 14:01
 */
public class TimeUtil {
    private  static  final org.slf4j.Logger logger = LoggerFactory.getLogger(TimeUtil.class);
    public static final SimpleDateFormat FMyyyyMMddHHmmss = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    public static final SimpleDateFormat FMyyyyMMdd= new SimpleDateFormat("yyyy-MM-dd");
    public static final SimpleDateFormat FMyyyyMM= new SimpleDateFormat("yyyy-MM");
    public static final SimpleDateFormat CN_FMyyyyMMdd= new SimpleDateFormat("yyyy年MM月dd日");
    public static final SimpleDateFormat yyyyMMdd= new SimpleDateFormat("yyyyMMdd");

    //自定义格式，格式化时间
    public static String getFormatDate(Date date, String aFormat) {
        String tDate =new SimpleDateFormat(aFormat).format(date);
        return tDate;
    }

    //yyyy-MM-dd HH:mm:ss格式时间字符串
    public static String getFormatDateTime(Date date) {
        String tDate =FMyyyyMMddHHmmss.format(date);
        return tDate;
    }

    //yyyy-MM-dd 格式时间字符串
    public static String getFormatDate(Date date) {
        String tDate =FMyyyyMMdd.format(date);
        return tDate;
    }

    //yyyy-MM格式时间字符串
    public static String getFormatYearMonth(Date date) {
        String tDate =FMyyyyMM.format(date);
        return tDate;
    }


    //yyyy年MM月dd日格式时间字符串
    public static String getCnFormatDateTime(Date date) {
        String tDate =CN_FMyyyyMMdd.format(date);
        return tDate;
    }

    //yyyy-MM-dd HH:mm:ss或者yyyy-MM-dd转换为日期类型
    public static Date parseFormatDateTime(String dateStr) {
        try {
            return dateStr.length()>12?FMyyyyMMddHHmmss.parse(dateStr):FMyyyyMMdd.parse(dateStr);
        } catch (ParseException e) {
            logger.error("无效的日期格式，{}",e);
            return null;
        }
    }

    //yyyyMMdd转换为日期类型
    public static Date parseIDFormatDate(String dateStr) {
        try {
            return new SimpleDateFormat("yyyyMMdd").parse(dateStr);
        } catch (ParseException e) {
            logger.error("无效的日期格式，{}",e);
            return null;
        }
    }

    /**
     * 获取今天的开始时间(日期类型)
     * @return
     */
    public static Date getTodayStart(){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(new Date(System.currentTimeMillis()));
        calendar.set(Calendar.HOUR_OF_DAY,0);
        calendar.set(Calendar.MINUTE,0);
        calendar.set(Calendar.SECOND,0);
        return calendar.getTime();
    }

    /**
     * 获取今天的开始时间(yyyy-MM-dd HH:mm:ss类型字符串)
     * @return
     */
    public static String getFormatTodayStart() {
        return getFormatDateTime(getTodayStart());
    }

    /**
     * 获取今天的结束时间(日期类型)
     * @return
     */
    public static Date getTodayEnd(){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(new Date(System.currentTimeMillis()));
        calendar.set(Calendar.HOUR_OF_DAY,23);
        calendar.set(Calendar.MINUTE,59);
        calendar.set(Calendar.SECOND,59);
        return calendar.getTime();
    }

    /**
     * 获取今天的结束时间(yyyy-MM-dd HH:mm:ss类型字符串)
     * @return
     */
    public static String getFormatTodayEnd() {
        return getFormatDateTime(getTodayEnd());
    }

    /**
     * 获取一天的开始时间(日期类型)
     * @param date
     * @return
     */
    public static Date getStartDateOfDay(Date date){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.HOUR_OF_DAY,0);
        calendar.set(Calendar.MINUTE,0);
        calendar.set(Calendar.SECOND,0);
        return calendar.getTime();
    }

    /**
     * 获取一天的开始时间(yyyy-MM-dd HH:mm:ss类型字符串)
     * @param date
     * @return
     */
    public static String getStartTimeOfDay(Date date){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.HOUR_OF_DAY,0);
        calendar.set(Calendar.MINUTE,0);
        calendar.set(Calendar.SECOND,0);
        return getFormatDateTime(calendar.getTime());
    }

    /**
     * 获取一天的开始时间
     * @param dateStr
     * @return
     */
    public static String getStartTimeOfDay(String dateStr){
        try {
            getStartTimeOfDay(FMyyyyMMdd.parse(dateStr));
        } catch (ParseException e) {
            logger.error("日期格式错误：{}",e);
        }
        return null;
    }

    /**
     * 某一个日期是否属于最近几天
     * @param date
     * @param days
     * @return
     */
    public boolean lastDay(Date date,Integer days){
        if(date==null) {
            return false;
        }
        Calendar ca= Calendar.getInstance();
        ca.roll(Calendar.DAY_OF_YEAR, -days);
        return date.after(ca.getTime());
    }

    /**
     * 获取一天的结束时间
     * @param date
     * @return
     */
    public static String getEndTimeOfDay(Date date){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.HOUR_OF_DAY,23);
        calendar.set(Calendar.MINUTE,59);
        calendar.set(Calendar.SECOND,59);
        return getFormatDateTime(calendar.getTime());
    }

    public static String getEndTimeOfDay(String dateStr){
        try {
            getEndTimeOfDay(FMyyyyMMdd.parse(dateStr));
        } catch (ParseException e) {
            logger.error("日期格式错误：{}",e);
        }
        return null;
    }

    /**
     * 获取下个月结束时间
     * @param currentTime
     * @return
     */
    public static Date getNextMonthTime(Date currentTime){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(currentTime);
        calendar.set(Calendar.HOUR_OF_DAY,23);
        calendar.set(Calendar.MINUTE,59);
        calendar.set(Calendar.SECOND,59);
        calendar.add(Calendar.MONTH,1);
        return calendar.getTime();
    }

    /**
     * 获取本月开始时间
     * @param currentTime
     * @return
     */
    public static Date getMonthStartTime(Date currentTime){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(currentTime);
        calendar.set(Calendar.HOUR_OF_DAY,0);
        calendar.set(Calendar.MINUTE,0);
        calendar.set(Calendar.SECOND,0);
        calendar.set(Calendar.DAY_OF_MONTH,1);
        return calendar.getTime();
    }

    /**
     * 获取本月开始时间
     * @param currentTime
     * @return
     */
    public static Date getMonthEndTime(Date currentTime){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(currentTime);
        calendar.set(Calendar.HOUR_OF_DAY,23);
        calendar.set(Calendar.MINUTE,59);
        calendar.set(Calendar.SECOND,59);
        calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
        return calendar.getTime();
    }

    /**
     * 取前后日期
     * @param currentTime 当前时间
     * @param stepLen 长度
     * @return
     */
    public static Date getNextDay(Date currentTime,int stepLen){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(currentTime);
        calendar.add(Calendar.DAY_OF_MONTH,stepLen);
        return calendar.getTime();
    }

    /**
     * 比较是否同一天
     * @param date1
     * @param date2
     * @return
     */
    public static boolean isSameDay(Date date1,Date date2){
        Calendar cal1 = Calendar.getInstance();
        cal1.setTime(date1);
        Calendar cal2 = Calendar.getInstance();
        cal2.setTime(date2);
        if(cal1 != null && cal2 != null) {
            return cal1.get(0) == cal2.get(0) && cal1.get(1) == cal2.get(1) && cal1.get(6) == cal2.get(6);
        } else {
            return false;
        }
    }

    /**
     * 获取天数区间
     * @param start
     * @param end
     * @return
     */
    public static int getDaysBetween(Date start, Date end) {
        Calendar d1 = Calendar.getInstance();
        d1.setTime(start);
        Calendar d2 = Calendar.getInstance();
        d2.setTime(end);
        if (d1.after(d2)) {
            Calendar swap = d1;
            d1 = d2;
            d2 = swap;
        }
        int days = d2.get(Calendar.DAY_OF_YEAR) - d1.get(Calendar.DAY_OF_YEAR);
        int y2 = d2.get(Calendar.YEAR);
        if (d1.get(Calendar.YEAR) != y2) {
            d1 = (Calendar) d1.clone();
            do {
                days += d1.getActualMaximum(Calendar.DAY_OF_YEAR);// 得到当年的实际天数
                d1.add(Calendar.YEAR, 1);

            } while (d1.get(Calendar.YEAR) != y2);
        }
        return days;
    }

    /**
     * 获取天数区间
     * @param start
     * @param end
     * @return
     */
    public static int getYearsBetween(Date start, Date end) {
        Calendar d1 = Calendar.getInstance();
        d1.setTime(start);
        Calendar d2 = Calendar.getInstance();
        d2.setTime(end);
        if (d1.after(d2)) {
            Calendar swap = d1;
            d1 = d2;
            d2 = swap;
        }
        return d2.get(Calendar.YEAR) - d1.get(Calendar.YEAR);
    }

    /**
     * 获取当前时间
     * @return
     */
    public static Date getCurrentDate() {
        return new Date(System.currentTimeMillis());
    }

    /**
     * 向一个老日期追加天数,返回一个新日期;
     * @param oldDate 被追加天数的日期;
     * @param days  追加的天数;
     * @return 返回一个日历对象,追加天数后的日期;通过Calendar.getTime()可获得;
     */
    public static Calendar addDaysFromOldDate(Date oldDate, int days) {
        // 添加结束时间;
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(oldDate);
        calendar.add(Calendar.DATE, days);
        return calendar;
    }
    
}

参考： https://blog.csdn.net/Solder_Sun/article/details/81364757