java 取当月起始日期，取出每一天

= Calendar.getInstance();
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        String firstday, lastday;
        cale.set(Calendar.DAY_OF_MONTH, 1);
        firstday = format.format(cale.getTime());
        cale.set(Calendar.DAY_OF_MONTH, cale.getActualMaximum(Calendar.DAY_OF_MONTH));
        lastday = format.format(cale.getTime());

        Calendar start =  Calendar.getInstance();
        start.setTime(format.parse(firstday));

        Calendar end = Calendar.getInstance();
        end.setTime(format.parse(lastday));

        List<String> days = new LinkedList<>();
        while (start.before(end)){
            days.add(format.format(start.getTime()));
            start.add(Calendar.DAY_OF_YEAR, 1);
        }
        days.add(lastday);