指定日期到當前日期的天數

public Long fundata( Date brithday )
    {
		//獲取當前日期
        Date nowDate = new Date();
		//轉爲毫秒值進行換算
        long nowSecond = nowDate.getTime();
        long birthdaySecond = brithday.getTime();
        //計算
        long second = nowSecond-birthdaySecond;
        if(second<0) {
            return null;
        }else {
            return second/1000/60/60/24;
        }
    }