计算两个时间差，单位天、小时、分钟、秒

输入类型为：java.util.Date，起始日期和结束日期，返回相差的时间差，支持单位天、小时、分钟、秒

//返回相差时间，单位：天
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
        {
            return day2-day1;
        }
    }
    //返回相差时间，单位：小时
    public static int differentDaysByMilliHours(Date date1,Date date2)
    {
        int days = (int) ((date2.getTime() - date1.getTime()) / (1000*60*60));
        return days;
    }

    //返回相差时间，单位：分钟
    public static int differentDaysByMillisecond(Date date1,Date date2)
    {
        int days = (int) ((date2.getTime() - date1.getTime()) / (1000*60));
        return days;
    }
    
    //返回相差时间，单位：秒
    public static int differentDaysByMillisecond(Date date1,Date date2)
    {
        int days = (int) ((date2.getTime() - date1.getTime()) / (1000));
        return days;
    }

    

亲测有效