java获取当天，前天，明天，本周，本月，本年的开始日期时间和结束日期时间

需要注意Calendar.HOUR和Calendar.Hour_OF_DAY的区别。

public class DateUtils {

	//获取当天的开始时间
	public static Date getDayBegin() {
		Calendar cal = new GregorianCalendar();
		cal.set(Calendar.HOUR_OF_DAY, 0);
		cal.set(Calendar.MINUTE, 0);
		cal.set(Calendar.SECOND, 0);
		cal.set(Calendar.MILLISECOND, 0);
		return cal.getTime();
	}

	//获取当天的结束时间
	public static Date getDayEnd() {
		Calendar cal = new GregorianCalendar();
		cal.set(Calendar.HOUR_OF_DAY, 23);
		cal.set(Calendar.MINUTE, 59);
		cal.set(Calendar.SECOND, 59);
		cal.set(Calendar.MILLISECOND, 999);
		return cal.getTime();
	}

	//获取当天的开始时间
	public static Long getDayBegin() {
		Calendar cal = new GregorianCalendar();
		cal.set(Calendar.HOUR_OF_DAY, 0);
		cal.set(Calendar.MINUTE, 0);
		cal.set(Calendar.SECOND, 0);
		cal.set(Calendar.MILLISECOND, 0);
		return cal.getTime().getTime();
	}

	//获取当天的结束时间
	public static Long getDayEnd() {
		Calendar cal = new GregorianCalendar();
		cal.set(Calendar.HOUR_OF_DAY, 23);
		cal.set(Calendar.MINUTE, 59);
		cal.set(Calendar.SECOND, 59);
		cal.set(Calendar.MILLISECOND, 999);
		return cal.getTime().getTime();
	}

	//获取昨天的开始时间
	public static Date getBeginDayOfYesterday() {
		Calendar cal = new GregorianCalendar();
		cal.setTime(getDayBegin());
		cal.add(Calendar.DAY_OF_MONTH, -1);
		return cal.getTime();
	}

	//获取昨天的结束时间
	public static Date getEndDayOfYesterDay() {
		Calendar cal = new GregorianCalendar();
		cal.setTime(getDayEnd());
		cal.add(Calendar.DAY_OF_MONTH, -1);
		return cal.getTime();
	}

	//获取明天的开始时间
	public static Date getBeginDayOfTomorrow() {
		Calendar cal = new GregorianCalendar();
		cal.setTime(getDayBegin());
		cal.add(Calendar.DAY_OF_MONTH, 1);
		return cal.getTime();
	}

	//获取明天的结束时间
	public static Date getEndDayOfTomorrow() {
		Calendar cal = new GregorianCalendar();
		cal.setTime(getDayEnd());
		cal.add(Calendar.DAY_OF_MONTH, 1);
		return cal.getTime();
	}

	//获取本周的开始时间
	public static Date getBeginDayOfWeek() {
		Date date = new Date();
		if (date == null) {
			return null;
		}
		Calendar cal = Calendar.getInstance();
		cal.setTime(date);
		int dayofweek = cal.get(Calendar.DAY_OF_WEEK);
		if (dayofweek == 1) {
			dayofweek += 7;
		}
		cal.add(Calendar.DATE, 2 - dayofweek);
		return getDayStartTime(cal.getTime());
	}

	//获取本周的结束时间
	public static Date getEndDayOfWeek(){
		Calendar cal = Calendar.getInstance();
		cal.setTime(getBeginDayOfWeek());  
		cal.add(Calendar.DAY_OF_WEEK, 6); 
		Date weekEndSta = cal.getTime();
		return getDayEndTime(weekEndSta);
	}

	//获取本月的开始时间
	public static Date getBeginDayOfMonth() {
		Calendar calendar = Calendar.getInstance();
		calendar.set(getNowYear(), getNowMonth() - 1, 1);
		return getDayStartTime(calendar.getTime());
	}

	//获取本月的结束时间
	public static Date getEndDayOfMonth() {
		Calendar calendar = Calendar.getInstance();
		calendar.set(getNowYear(), getNowMonth() - 1, 1);
		int day = calendar.getActualMaximum(5);
		calendar.set(getNowYear(), getNowMonth() - 1, day);
		return getDayEndTime(calendar.getTime());
	}

	//获取本年的开始时间
	public static Date getBeginDayOfYear() {
		Calendar cal = Calendar.getInstance();
		cal.set(Calendar.YEAR, getNowYear());
		cal.set(Calendar.MONTH, Calendar.JANUARY);
		cal.set(Calendar.DATE, 1);
		return getDayStartTime(cal.getTime());
	}

	//获取本年的结束时间
	public static Date getEndDayOfYear() {
		Calendar cal = Calendar.getInstance();
		cal.set(Calendar.YEAR, getNowYear());
		cal.set(Calendar.MONTH, Calendar.DECEMBER);
		cal.set(Calendar.DATE, 31);
		return getDayEndTime(cal.getTime());
	}

	//获取某个日期的开始时间
	public static Timestamp getDayStartTime(Date d) {
		Calendar calendar = Calendar.getInstance();
		if(null != d){
			calendar.setTime(d);
		}
		calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
		calendar.set(Calendar.MILLISECOND, 0);
		return new Timestamp(calendar.getTimeInMillis());
	}

	//获取某个日期的结束时间
	public static Timestamp getDayEndTime(Date d) {
		Calendar calendar = Calendar.getInstance();
		if(null != d) {
			calendar.setTime(d);
		}
		calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH), 23, 59, 59);
		calendar.set(Calendar.MILLISECOND, 999);
		return new Timestamp(calendar.getTimeInMillis());
	}

	//获取今年是哪一年
	public static Integer getNowYear() {
		Date date = new Date();
		GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
		gc.setTime(date);
		return Integer.valueOf(gc.get(1));
	}

	//获取本月是哪一月
	public static int getNowMonth() {
		Date date = new Date();
		GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
		gc.setTime(date);
		return gc.get(2) + 1;
	}

	//两个日期相减得到的天数
	public static int getDiffDays(Date beginDate, Date endDate) {
		if (beginDate == null || endDate == null) {
			throw new IllegalArgumentException("getDiffDays param is null!");
		}
		long diff = (endDate.getTime() - beginDate.getTime())/ (1000 * 60 * 60 * 24);
		int days = new Long(diff).intValue();
		return days;
	}

	//两个日期相减得到的毫秒数
	public static long dateDiff(Date beginDate, Date endDate) {
		long date1ms = beginDate.getTime();
		long date2ms = endDate.getTime();
		return date2ms - date1ms;
	}

	//获取两个日期中的最大日期
	public static Date max(Date beginDate, Date endDate) {
		if (beginDate == null) {
			return endDate;
		}
		if (endDate == null) {
			return beginDate;
		}
		if (beginDate.after(endDate)) {
			return beginDate;
		}
		return endDate;
	}

	//获取两个日期中的最小日期
	public static Date min(Date beginDate, Date endDate) {
		if (beginDate == null) {
			return endDate;
		}
		if (endDate == null) {
			return beginDate;
		}
		if (beginDate.after(endDate)) {
			return endDate;
		}
		return beginDate;
	}

	//返回某月该季度的第一个月
	public static Date getFirstSeasonDate(Date date) {
		final int[] SEASON = { 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4 };
		Calendar cal = Calendar.getInstance();
		cal.setTime(date);
		int sean = SEASON[cal.get(Calendar.MONTH)];
		cal.set(Calendar.MONTH, sean * 3 - 3);
		return cal.getTime();
	}

	//返回某个日期下几天的日期
	public static Date getNextDay(Date date, int i) {
		Calendar cal = new GregorianCalendar();
		cal.setTime(date);
		cal.set(Calendar.DATE, cal.get(Calendar.DATE) + i);
		return cal.getTime();
	}

	//返回某个日期前几天的日期
	public static Date getFrontDay(Date date, int i) {
		Calendar cal = new GregorianCalendar();
		cal.setTime(date);
		cal.set(Calendar.DATE, cal.get(Calendar.DATE) - i);
		return cal.getTime();
	}

	//获取某年某月到某年某月按天的切片日期集合（间隔天数的日期集合）
	public static List getTimeList(int beginYear, int beginMonth, int endYear,int endMonth, int k) {
		List list = new ArrayList();
		if (beginYear == endYear) {
			for (int j = beginMonth; j <= endMonth; j++) {
				list.add(getTimeList(beginYear, j, k));
			}
		} else {
			for (int j = beginMonth; j < 12; j++) {
				list.add(getTimeList(beginYear, j, k));
			}
			for (int i = beginYear + 1; i < endYear; i++) {
				for (int j = 0; j < 12; j++) {
					list.add(getTimeList(i, j, k));
				}
			}
			for (int j = 0; j <= endMonth; j++) {
				list.add(getTimeList(endYear, j, k));
			}
		}
		return list;
	}

	//获取某年某月按天切片日期集合（某个月间隔多少天的日期集合）
	public static List getTimeList(int beginYear, int beginMonth, int k) {
		List list = new ArrayList();
		Calendar begincal = new GregorianCalendar(beginYear, beginMonth, 1);
		int max = begincal.getActualMaximum(Calendar.DATE);
		for (int i = 1; i < max; i = i + k) {
			list.add(begincal.getTime());
			begincal.add(Calendar.DATE, k);
		}
		begincal = new GregorianCalendar(beginYear, beginMonth, max);
		list.add(begincal.getTime());
		return list;
	}

	//获取某年某月的第一天日期
	public static Date getStartMonthDate(int year, int month) {
		Calendar calendar = Calendar.getInstance();
		calendar.set(year, month - 1, 1);
		return calendar.getTime();
	}

	//获取某年某月的最后一天日期
	public static Date getEndMonthDate(int year, int month) {
		Calendar calendar = Calendar.getInstance();
		calendar.set(year, month - 1, 1);
		int day = calendar.getActualMaximum(5);
		calendar.set(year, month - 1, day);
		return calendar.getTime();
	}
}

内容借鉴：https://www.cnblogs.com/suruozhong/p/6085380.html?utm_source=itdadao&utm_medium=referral