LocalDateTime 获取当前月第一天及最后一天 及 获取当天起始时间

        // 获取当前月第一天及最后一天
        LocalDateTime firstDayOfMonth = LocalDateTime.of(LocalDate.from(LocalDateTime.now().with(TemporalAdjusters.firstDayOfMonth())), LocalTime.MIN);
        LocalDateTime lastDayOfMonth = LocalDateTime.of(LocalDate.from(LocalDateTime.now().with(TemporalAdjusters.lastDayOfMonth())), LocalTime.MAX);