由月周日 获取当月的月周日 准确日期

private static final Integer MONTH = 1;
private static final Integer WEEK = 2;
private static final Integer DAY = 3;

/**
     * 根据状态获取默认日期(月、周、日)
     * @param num
     * @param instance
     * @return
     */
    List<String> authDateByNum(Integer num, Calendar instance){
        SimpleDateFormat sdf;
        int max = 0;
        List<String> list = new ArrayList<>();
        if(MONTH.equals(num) || WEEK.equals(num)){
            sdf  = new SimpleDateFormat("MM/dd");
            if(MONTH.equals(num)){
                 max = instance.getActualMaximum(Calendar.DAY_OF_MONTH);
            } else {
                 max = instance.getActualMaximum(Calendar.DAY_OF_WEEK);
            }
        } else {
            sdf = new SimpleDateFormat("HH:mm");
             max = instance.getActualMaximum(Calendar.HOUR_OF_DAY);
        }
        for (int i = 0; i < max; i++) {
            if(MONTH.equals(num)){
                instance.set(Calendar.DAY_OF_MONTH, i + 1);
            } else if ( WEEK.equals(num)){
                instance.set(Calendar.DAY_OF_WEEK, i + 1);
            } else {
                instance.set(Calendar.HOUR_OF_DAY, i + 1);
                instance.set(Calendar.MINUTE,0);
            }
            String day = sdf.format(instance.getTime());
            list.add(day);
        }
        return list;
    }