获取给定年月，当月有几周，每周开始结束日期

package date;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAdjusters;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
 * 获取给定年月计算当月有几周，每周的开始和结束日期
 * @author pei
 *
 */

public class TestLocal {
	static DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
	
	public static void main(String[] args) {
		
		List<Map> list =  getScope();
		System.out.println("list====="+list);


	}
	
	
	public static List<Map> getScope() {
        String date = "2023-01-01";
        String timeStrs[] = date.split("-");
        Calendar c = Calendar.getInstance();
        c.set(Calendar.YEAR, Integer.parseInt(timeStrs[0]));
        c.set(Calendar.MONTH, Integer.parseInt(timeStrs[1]) - 1);
        c.setFirstDayOfWeek(Calendar.MONDAY);
        int weeks = c.getActualMaximum(Calendar.WEEK_OF_MONTH);

        LocalDate localDateate = LocalDate.parse(date, dateTimeFormatter);
        //月份第一周的起始时间和结束时间
        LocalDate firstDay = localDateate.with(TemporalAdjusters.firstDayOfMonth());
        String firstDayStr = firstDay.format(dateTimeFormatter);
        String sunStr = getSunOfWeek(firstDayStr);

        List<Map> weekInfos = new ArrayList<>();
        for (int i = 1; i <= weeks; i++) {
            Map weekInfo = new HashMap();
            //第一周的起始时间就是当月的1号，结束时间就是周日
            if (i == 1) {
                weekInfo.put("start",firstDayStr);
                weekInfo.put("end",sunStr);
                weekInfo.put("order",i);
                //计算接下来每周的周一和周日
            } else if (i < weeks) {
                //由于sunStr是上一周的周日，所以取周一要取sunStr的下一周的周一
                String monDay = getLastMonOfWeek(sunStr);
                sunStr = getSunOfWeek(monDay);
                weekInfo.put("start",monDay);
                weekInfo.put("end",sunStr);
                weekInfo.put("order",i);
                //由于最后一周可能结束时间不是周日，所以要单独处理
            } else {
                String monDay = getLastMonOfWeek(sunStr);
                //结束时间肯定就是当前月的最后一天
                LocalDate lastDay = localDateate.with(TemporalAdjusters.lastDayOfMonth());
                String endDay = lastDay.format(dateTimeFormatter);
                weekInfo.put("start",monDay);
                weekInfo.put("end",endDay);
                weekInfo.put("order",i);
            }

            weekInfos.add(weekInfo);

        }
        return weekInfos;
    }
	
	//算出所在周的周日
    public static String getSunOfWeek(String time) {
        LocalDate localDateate = LocalDate.parse(time, dateTimeFormatter);
        LocalDate endday = localDateate.with(TemporalAdjusters.next(java.time.DayOfWeek.MONDAY)).minusDays(1);
        String endDayStr = endday.format(dateTimeFormatter);
        return endDayStr;
    }

    //下一周的周一
    public static String getLastMonOfWeek(String time) {
        LocalDate localDateate = LocalDate.parse(time, dateTimeFormatter);
        LocalDate endday = localDateate.with(TemporalAdjusters.next(java.time.DayOfWeek.MONDAY));
        String endDayStr = endday.format(dateTimeFormatter);
        return endDayStr;
    }

}