获取参数月份的开始时间和结束时间

// 获取当月的开始时间和结束时间 参数date为yyyy-MM
LocalDate firstDayOfMonth = LocalDate.parse(date + "-01"); // 获取当月开始时间
LocalDate lastDayOfMonth = 
	firstDayOfMonth.with(TemporalAdjusters.lastDayOfMonth());// 获取当月结束时间

根据两个时间段获取每一天

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * 根据两个时间段获取每一天
 */
public class ObtainBetweenDateUtils {
    public static Set getBetweenDate(String start,String end){
        LocalDate startDate = LocalDate.parse(start);
        LocalDate endDate = LocalDate.parse(end);
        long between = ChronoUnit.DAYS.between(startDate, endDate);
        if (between < 1) {
            return Stream.of(start, end).collect(Collectors.toSet());
        }
        return Stream.iterate(startDate, e -> e.plusDays(1))
                .limit(between + 1).map(LocalDate::toString).collect(Collectors.toSet());
    }

}

Java获取当月开始时间和当月结束时间

public class Time{

    private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
    
   public static void main(String[] args){
   
        Calendar calendar= Calendar.getInstance();
        SimpleDateFormat dateFormat= new SimpleDateFormat("yyyy-MM-dd ");
        String format = dateFormat.format(calendar.getTime());
        String minMonthDate = getMinMonthDate(format);
        String s = minMonthDate+" 00:00:00";
        System.out.println(s); //2020-11-01 00:00:00
        String maxMonthDate = getMaxMonthDate(format);
        String e = maxMonthDate+" 59:59:59";
        System.out.println(e); //2020-11-30 59:59:59
   
   }



    // 获得当前月--开始日期
    public static String getMinMonthDate(String date) {
        Calendar calendar = Calendar.getInstance();
        try {
            calendar.setTime(dateFormat.parse(date));
            calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
            return dateFormat.format(calendar.getTime());
        } catch (java.text.ParseException e) {
            e.printStackTrace();
        }
        return null;
    }

    // 获得当前月--结束日期
    public static String getMaxMonthDate(String date){
        Calendar calendar = Calendar.getInstance();
        try {
            calendar.setTime(dateFormat.parse(date));
            calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
            return dateFormat.format(calendar.getTime());
        }  catch (java.text.ParseException e) {
            e.printStackTrace();
        }
         return null;
       }
    }

java中接收了一个String类型的年月的参数，获取该月的开始年月日和结束的年月日

import java.time.LocalDate;
import java.time.temporal.TemporalAdjusters;

public class DateExample {
    public static void main(String[] args) {
        String yearMonth = "2023-08";
        LocalDate firstDayOfMonth = LocalDate.parse(yearMonth + "-01");
        LocalDate lastDayOfMonth = firstDayOfMonth.with(TemporalAdjusters.lastDayOfMonth());

        System.out.println("开始年月日：" + firstDayOfMonth);
        System.out.println("结束年月日：" + lastDayOfMonth);
    }
}