获取指定月份前的第一天和最后一天及两个日期之间的月份列表

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    public static Map<String,String> getMonthMap(int month){
        Map<String,String> monthMap = new HashMap<>();
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        // 获取前月的第一天
        Calendar cal_1 = Calendar.getInstance();// 获取当前日期
        cal_1.add(Calendar.MONTH, -month);
        cal_1.set(Calendar.DAY_OF_MONTH, 1);// 设置为1号,当前日期既为本月第一天
        String firstDay = format.format(cal_1.getTime());
        // 获取前月的最后一天
        Calendar cale = Calendar.getInstance();
        cale.add(Calendar.MONTH, -(month-1));
        cale.set(Calendar.DAY_OF_MONTH, 0);
        String lastDay = format.format(cale.getTime());
        monthMap.put("firstDay", firstDay);
        monthMap.put("lastDay", lastDay);
        return monthMap;
    }

---获取两个日期之间相差的月份：

    public static List<String> getMonthBetween(String start, String end) {
        List<String> result = new ArrayList<>();
        try {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            Calendar min = Calendar.getInstance();
            Calendar max = Calendar.getInstance();

            min.setTime(sdf.parse(start));
            min.set(min.get(Calendar.YEAR), min.get(Calendar.MONTH), 1);

            max.setTime(sdf.parse(end));
            max.set(max.get(Calendar.YEAR), max.get(Calendar.MONTH), 2);

            Calendar curr = min;
            while (curr.before(max)) {
                result.add(sdf.format(curr.getTime()));
                curr.add(Calendar.MONTH, 1);
            }
        } catch (Exception e) {
            LOGGER.error(e.getMessage(), e);
        }

        return result;
    }