java計算兩個日期之間相隔的月份（向下取整）

最近需求裏面有個須要計算兩個日期之間相隔的月份，寫起來還挺繁瑣，須要將各類狀況都要考慮到，寫了一個做爲之後本身的工具吧。

 1 //獲取哪一天
 2     public static int getDay(Date date) {  3         Calendar calendar = Calendar.getInstance();  4  calendar.setTime(date);  5         return calendar.get(Calendar.DATE);  6  }  7 
 8     /**
 9  * 返回日期的月份，1-12,即yyyy-MM-dd中的MM 10  * 11  * @param date 12  * @return
13      */
14     public static int getMonth(Date date) { 15         Calendar calendar = Calendar.getInstance(); 16  calendar.setTime(date); 17         return calendar.get(Calendar.MONTH) + 1; 18  } 19 
20     /**
21  * 返回日期的年,即yyyy-MM-dd中的yyyy 22  * 23  * @param date 24  * Date 25  * @return int 26      */
27     public static int getYear(Date date) { 28         Calendar calendar = Calendar.getInstance(); 29  calendar.setTime(date); 30         return calendar.get(Calendar.YEAR); 31  } 32     public static int calDiffMonth(String startDate,String endDate) { 33         int result=0; 34         try { 35             SimpleDateFormat sfd=new SimpleDateFormat("yyyyMMdd"); 36             Date start = sfd.parse(startDate); 37             Date end = sfd.parse(endDate); 38             int startYear=getYear(start); 39             int startMonth=getMonth(start); 40             int startDay=getDay(start); 41             int endYear=getYear(end); 42             int endMonth=getMonth(end); 43             int endDay=getDay(end); 44             
45             Calendar calendar2= Calendar.getInstance(); 46  calendar2.setTime(start); 47             int maxDay = calendar2.getActualMaximum(Calendar.DAY_OF_MONTH);//獲取起始日期所在月的最後一天
48             Calendar calendar3 = Calendar.getInstance(); 49  calendar3.setTime(end); 50             int maxEndDay = calendar3.getActualMaximum(Calendar.DAY_OF_MONTH);//獲取結束日期所在月的最後一天
51             if(startDay == maxDay){//起始日期是在月末
52                 if(maxEndDay==endDay){ 53                     result=(endYear-startYear)*12+endMonth-startMonth; 54                 }else { 55                     result=(endYear-startYear)*12+endMonth-startMonth-1; 56  } 57             }else if(endDay==maxEndDay){//結束日期是在月末
58                 result=(endYear-startYear)*12+endMonth-startMonth; 59             }else { 60                 if (endDay >= startDay) { 61                     result=(endYear-startYear)*12+endMonth-startMonth; 62                 }else { 63                     result=(endYear-startYear)*12+endMonth-startMonth-1; 64  } 65  } 66         } catch (Exception e) { 67  e.printStackTrace(); 68  } 69         return result; 70  } 71 
72 
73     public static void main(String[] args) { 74         int i = calDiffMonth("20171030", "20180228"); 75  System.out.println(i); 76     }