java—获取某月的第一天和最后一天

        //  获取给定年、月的第1天
        LocalDate firstDay = LocalDate.of(year, month, 1);
        //  获取该月的最后1天(https://java2blog.com/last-day-of-month-java)
        LocalDate lastDay = firstDay.withDayOfMonth(
                firstDay.getMonth().length(firstDay.isLeapYear())
        );