根据年和月计算对应的天数

    /**
     * 计算大小月
     * @return
     */
    public static String calDate(String date){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");
        Calendar days = Calendar.getInstance();
        try {
            days.setTime(sdf.parse(date));
        } catch (ParseException e) {
            e.printStackTrace();
        }
        int resultDays = days.getActualMaximum(Calendar.DAY_OF_MONTH);
        return Integer.valueOf(resultDays).toString();
    }