一、返回 LocalDateTime 格式的起止时间

/**
 * @Description:返回 LocalDateTime 格式的日、周、月、季度、年起止时间
 * @Author: lsiyan
 * @Date: 2020/8/21 22:47
 */
import java.time.*;
import java.time.temporal.TemporalAdjusters;

/**
 * jdk8 获取当天，本周，本月，本季度，本年起始时间工具类 LocalDateTime
 */
public class LocalDateTimeUtils {

	public static final String MinTime = "T00:00:00";
	public static final String MaxTime = "T23:59:59.999999999";


	/**
	 * @Description:当天的开始时间
	 * @Param: [today, isFirst: true 表示开始时间，false表示结束时间]
	 */
	public static LocalDateTime getStartOrEndDayOfDay(LocalDate today, Boolean isFirst){
		LocalDate resDate = LocalDate.now();
		if (today == null) {
			today = resDate;
		}
		if(isFirst){
			return LocalDateTime.of(today, LocalTime.MIN);
		}else{
			return LocalDateTime.of(today, LocalTime.MAX);
		}
	}

	/**
	 * @Description:本周的开始时间
	 * @Param: [today, isFirst: true 表示开始时间，false表示结束时间]
	 */
	public static LocalDateTime getStartOrEndDayOfWeek(LocalDate today, Boolean isFirst){
		String time = MinTime;
		LocalDate resDate = LocalDate.now();
		if (today == null) {
			today = resDate;
		}
		DayOfWeek week = today.getDayOfWeek();
		int value = week.getValue();
		if (isFirst) {
			resDate = today.minusDays(value - 1);
		} else {
			resDate = today.plusDays(7 - value);
			time = MaxTime;
		}
		LocalDateTime localDateTime = LocalDateTime.parse(resDate.toString() + time);
		return localDateTime;
	}

	/**
	 * @Description:本月的开始时间
	 * @Param: [today, isFirst: true 表示开始时间，false表示结束时间]
	 */
	public static LocalDateTime getStartOrEndDayOfMonth(LocalDate today, Boolean isFirst){
		String time = MinTime;
		LocalDate resDate = LocalDate.now();
		if (today == null) {
			today = resDate;
		}
		Month month = today.getMonth();
		int length = month.length(today.isLeapYear());
		if (isFirst) {
			resDate = LocalDate.of(today.getYear(), month, 1);
		} else {
			resDate = LocalDate.of(today.getYear(), month, length);
			time = MinTime;
		}
		LocalDateTime localDateTime = LocalDateTime.parse(resDate.toString() + time);
		return localDateTime;
	}

	/**
	 * @Description:本季度的开始时间
	 * @Param: [today, isFirst: true 表示开始时间，false表示结束时间]
	 */
	public static LocalDateTime getStartOrEndDayOfQuarter(LocalDate today, Boolean isFirst){
		String time = MinTime;
		LocalDate resDate = LocalDate.now();
		if (today == null) {
			today = resDate;
		}
		Month month = today.getMonth();
		Month firstMonthOfQuarter = month.firstMonthOfQuarter();
		Month endMonthOfQuarter = Month.of(firstMonthOfQuarter.getValue() + 2);
		if (isFirst) {
			resDate = LocalDate.of(today.getYear(), firstMonthOfQuarter, 1);
		} else {
			resDate = LocalDate.of(today.getYear(), endMonthOfQuarter, endMonthOfQuarter.length(today.isLeapYear()));
			time = MaxTime;
		}
		LocalDateTime localDateTime = LocalDateTime.parse(resDate.toString() + time);
		return localDateTime;
	}

	/**
	 * @Description:本年度的开始时间
	 * @Param: [today, isFirst: true 表示开始时间，false表示结束时间]
	 */
	public static LocalDateTime getStartOrEndDayOfYear(LocalDate today, Boolean isFirst){
		String time = MinTime;
		LocalDate resDate = LocalDate.now();
		if (today == null) {
			today = resDate;
		}
		if (isFirst) {
			resDate = LocalDate.of(today.getYear(), Month.JANUARY, 1);
		} else {
			resDate = LocalDate.of(today.getYear(), Month.DECEMBER, Month.DECEMBER.length(today.isLeapYear()));
			time = MaxTime;
		}
		LocalDateTime localDateTime = LocalDateTime.parse(resDate.toString() + time);
		return localDateTime;
	}

二、返回 String 格式的起止时间

/**
 * @Description:返回 String 格式的周、月、季度、年起止时间
 * @Author: lsiyan
 * @Date: 2020/8/21 22:47
 */
import java.time.*;
import java.time.temporal.TemporalAdjusters;

/**
 * jdk8 获取本周，本月，本季度，本年起始时间工具类 String
 */
public class LocalDateTimeUtils {

	//本周的开始时间
	public static String getStartOrEndDayOfWeek(LocalDate today, Boolean isFirst){
		LocalDate resDate = LocalDate.now();
		if (today == null) {
			today = resDate;
		}
		DayOfWeek week = today.getDayOfWeek();
		int value = week.getValue();
		if (isFirst) {
			resDate = today.minusDays(value - 1);
		} else {
			resDate = today.plusDays(7 - value);
		}
		return resDate.toString();
	}

	//本月的开始时间
	public static String getStartOrEndDayOfMonth(LocalDate today, Boolean isFirst){
		LocalDate resDate = LocalDate.now();
		if (today == null) {
			today = resDate;
		}
		Month month = today.getMonth();
		int length = month.length(today.isLeapYear());
		if (isFirst) {
			resDate = LocalDate.of(today.getYear(), month, 1);
		} else {
			resDate = LocalDate.of(today.getYear(), month, length);
		}
		return resDate.toString();
	}

	//本季度开始时间
	public static String getStartOrEndDayOfQuarter(LocalDate today, Boolean isFirst){
		LocalDate resDate = LocalDate.now();
		if (today == null) {
			today = resDate;
		}
		Month month = today.getMonth();
		Month firstMonthOfQuarter = month.firstMonthOfQuarter();
		Month endMonthOfQuarter = Month.of(firstMonthOfQuarter.getValue() + 2);
		if (isFirst) {
			resDate = LocalDate.of(today.getYear(), firstMonthOfQuarter, 1);
		} else {
			resDate = LocalDate.of(today.getYear(), endMonthOfQuarter, endMonthOfQuarter.length(today.isLeapYear()));
		}
		return resDate.toString();
	}

	//本年度开始时间
	public static String getStartOrEndDayOfYear(LocalDate today, Boolean isFirst){
		LocalDate resDate = LocalDate.now();
		if (today == null) {
			today = resDate;
		}
		if (isFirst) {
			resDate = LocalDate.of(today.getYear(), Month.JANUARY, 1);
		} else {
			resDate = LocalDate.of(today.getYear(), Month.DECEMBER, Month.DECEMBER.length(today.isLeapYear()));
		}
		return resDate.toString();
	}

	public static void main(String[] args) {
		System.out.println("本周开始时间>>>" + getStartOrEndDayOfWeek(null, true));
		System.out.println("本周结束时间>>>" + getStartOrEndDayOfWeek(null, false));

		System.out.println("本月开始时间>>>" + getStartOrEndDayOfMonth(null, true));
		System.out.println("本月结束时间>>>" + getStartOrEndDayOfMonth(null, false));

		System.out.println("本季度开始时间>>>" + getStartOrEndDayOfQuarter(null, true));
		System.out.println("本季度结束时间>>>" + getStartOrEndDayOfQuarter(null, false));

		System.out.println("本年开始时间>>>" + getStartOrEndDayOfYear(null, true));
		System.out.println("本年结束时间>>>" + getStartOrEndDayOfYear(null, false));
	}
}