Java两个日期相差的天数

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Java两个日期相差的天数

 /**
     * date2比date1多的天数
     * @param date1
     * @param date2
     * @return
     */
    public static int differentDays(Date date1,Date date2)
    {
        Calendar cal1 = Calendar.getInstance();
        cal1.setTime(date1);

        Calendar cal2 = Calendar.getInstance();
        cal2.setTime(date2);
        int day1= cal1.get(Calendar.DAY_OF_YEAR);
        int day2 = cal2.get(Calendar.DAY_OF_YEAR);

        int year1 = cal1.get(Calendar.YEAR);
        int year2 = cal2.get(Calendar.YEAR);
        if(year1 != year2)   //同一年
        {
            int timeDistance = 0 ;
            for(int i = year1 ; i < year2 ; i ++)
            {
                if(i%4==0 && i%100!=0 || i%400==0)    //闰年
                {
                    timeDistance += 366;
                }
                else    //不是闰年
                {
                    timeDistance += 365;
                }
            }

            return timeDistance + (day2-day1) ;
        }
        else    //不同年
        {
            System.out.println("判断day2 - day1 : " + (day2-day1));
            return day2-day1;
        }
    }

  @org.junit.Test
    public void testStepsSize2() {
        int[] arr = {1, 2, 3, 6, 7, 9, 9, 10, 11, 12, 13, 14, 15,16};

        String dateStr = "2015-1-1 21:21:28";
        String dateStr2 = "2015-1-4 1:21:28";
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        SimpleDateFormat format2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        try
        {
            Date date2 = format.parse(dateStr2);
            Date date = format.parse(dateStr);

            System.out.println("两个日期的差距：" + CheckString.differentDays(date,date2));
        } catch (ParseException e) {
            e.printStackTrace();
        }
}