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1. 根据指定日期获取周，月，季度，年的第一天和最后一天

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;/*** 根据给定时间获取周、月度、季度、年度开始结束时间*/
public class DateCalendarUtil {/*** @Description: 获取月份第一天* @Author: wsp**/public static Calendar getMonthStart(Date date) {// 月份开始Calendar startCalendar = Calendar.getInstance();startCalendar.setTime(date);//set方法将给定日历字段设置为给定值// 下面代码作用是将日历设置为给定日期月份天数的第一天startCalendar.set(Calendar.DAY_OF_MONTH, 1);return startCalendar;}/*** 获取月份最后一天* @param date* @return*/public static Calendar getMonthEnd(Date date) {// 月份结束Calendar endCalendar = Calendar.getInstance();endCalendar.setTime(date);//getActualMaximum方法用来返回给定日历字段属性的最大值// endCalendar.getActualMaximum(Calendar.DAY_OF_MONTH) 代码作用为返回日历该月份的最大值// set方法，将该日历的给定月份设置为最大天数endCalendar.set(Calendar.DAY_OF_MONTH, endCalendar.getActualMaximum(Calendar.DAY_OF_MONTH));return endCalendar;}/*** 获取季度第一天* 1.根据给定日期计算当前季度的第一个月份* 2.设置日历的月份为当前季度的第一个月份* 3.最后设置日历月份天数为第一天即可* @param date* @return*/public static Calendar getQuarterStart(Date date) {Calendar startCalendar = Calendar.getInstance();startCalendar.setTime(date);//get方法：获取给定日历属性的值，如 endCalendar.get(Calendar.MONTH) 获取日历的月份// 计算季度数：由于月份从0开始，即1月份的Calendar.MONTH值为0,所以计算季度的第一个月份只需 月份 / 3 * 3startCalendar.set(Calendar.MONTH, (((int) startCalendar.get(Calendar.MONTH)) / 3) * 3);startCalendar.set(Calendar.DAY_OF_MONTH, 1);return startCalendar;}/*** 获取季度最后一天* @param date* @return*/public static Calendar getQuarterEnd(Date date) {// 季度结束Calendar endCalendar = Calendar.getInstance();endCalendar.setTime(date);//计算季度数：由于月份从0开始，即1月份的Calendar.MONTH值为0,所以计算季度的第三个月份只需 月份 / 3 * 3 + 2endCalendar.set(Calendar.MONTH, (((int) endCalendar.get(Calendar.MONTH)) / 3) * 3 + 2);endCalendar.set(Calendar.DAY_OF_MONTH, endCalendar.getActualMaximum(Calendar.DAY_OF_MONTH));return endCalendar;}/*** 获取年份第一天* @param date* @return*/public static Calendar getYearStart(Date date) {// 年份开始Calendar startCalendar = Calendar.getInstance();startCalendar.setTime(date);startCalendar.set(Calendar.DAY_OF_YEAR, 1);return startCalendar;}/*** 获取年份最后一天* @param date* @return*/public static Calendar getYearEnd(Date date) {// 年份结束Calendar endCalendar = Calendar.getInstance();endCalendar.setTime(date);endCalendar.set(Calendar.DAY_OF_YEAR, endCalendar.getActualMaximum(Calendar.DAY_OF_YEAR));return endCalendar;}/*** 获取当前周第一天（周一）* @param date* @return*/public static Date getWeekStart(Date date) {Calendar calendar = Calendar.getInstance();calendar.setTime(date);//获取传入日期属于星期几，根据星期几进行不同处理int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);//周日：需要减去6天为周一。（当传入日期为周日时，若我们直接设置日历天数为周一，则日期会变为下一周的周一，而非当前周）if (dayOfWeek == 1) {calendar.add(Calendar.DAY_OF_MONTH, -6);} else {//周二 至 周六：直接获取周一即可calendar.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);}return calendar.getTime();}/*** 获取当前周最后一天（周日）* @param date* @return*/public static Date getWeekEnd(Date date) {Calendar calendar = Calendar.getInstance();calendar.setTime(getWeekStart(date));calendar.add(Calendar.DAY_OF_MONTH, 6);return calendar.getTime();}public static void main(String[] args) throws ParseException {String dateStr = "2023-08-15";SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");Date date = sdf.parse(dateStr);String startMonthDay = sdf.format(getMonthStart(date).getTime());String endMonthDay = sdf.format(getMonthEnd(date).getTime());System.out.printf("月份的第一天：%s, 月份的最后一天：%s%n", startMonthDay, endMonthDay);String startQuarterDay = sdf.format(getQuarterStart(date).getTime());String endQuarterDay = sdf.format(getQuarterEnd(date).getTime());System.out.printf("季度第一天：%s, 季度最后一天：%s%n", startQuarterDay, endQuarterDay);String startYearDay = sdf.format(getYearStart(date).getTime());String endYearDay = sdf.format(getYearEnd(date).getTime());System.out.printf("年份第一天：%s, 年份最后一天：%s%n", startYearDay, endYearDay);String startWeekDay = sdf.format(getWeekStart(date));String endWeekDay = sdf.format(getWeekEnd(date));System.out.printf("当前周周一：%s, 当前周周日：%s%n", startWeekDay, endWeekDay);}}