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);
     }