java计算两个日期之间相隔的月份（向下取整）

最近需求里面有个需要计算两个日期之间相隔的月份，写起来还挺繁琐，需要将各种情况都要考虑到，写了一个作为以后自己的工具吧。

//获取哪一天
    public static int getDay(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.DATE);
    }

    /**
     * 返回日期的月份，1-12,即yyyy-MM-dd中的MM
     *
     * @param date
     * @return
     */
    public static int getMonth(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.MONTH) + 1;
    }

    /**
     * 返回日期的年,即yyyy-MM-dd中的yyyy
     *
     * @param date
     *            Date
     * @return int
     */
    public static int getYear(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.YEAR);
    }
    public static int calDiffMonth(String startDate,String endDate) {
        int result=0;
        try {
            SimpleDateFormat sfd=new SimpleDateFormat("yyyyMMdd");
            Date start = sfd.parse(startDate);
            Date end = sfd.parse(endDate);
            int startYear=getYear(start);
            int startMonth=getMonth(start);
            int startDay=getDay(start);
            int endYear=getYear(end);
            int endMonth=getMonth(end);
            int endDay=getDay(end);
            
            Calendar calendar2= Calendar.getInstance();
            calendar2.setTime(start);
            int maxDay = calendar2.getActualMaximum(Calendar.DAY_OF_MONTH);//获取起始日期所在月的最后一天
            Calendar calendar3 = Calendar.getInstance();
            calendar3.setTime(end);
            int maxEndDay = calendar3.getActualMaximum(Calendar.DAY_OF_MONTH);//获取结束日期所在月的最后一天
            if(startDay == maxDay){//起始日期是在月末
                if(maxEndDay==endDay){
                    result=(endYear-startYear)*12+endMonth-startMonth;
                }else {
                    result=(endYear-startYear)*12+endMonth-startMonth-1;
                }
            }else if(endDay==maxEndDay){//结束日期是在月末
                result=(endYear-startYear)*12+endMonth-startMonth;
            }else {
                if (endDay >= startDay) {
                    result=(endYear-startYear)*12+endMonth-startMonth;
                }else {
                    result=(endYear-startYear)*12+endMonth-startMonth-1;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }


    public static void main(String[] args) {
        int i = calDiffMonth("20171030", "20180228");
        System.out.println(i);
    }