獲取當前日期前x天日期

代碼片斷以下

/**
     * 獲取x天前的日期
     */
    private static String getDay(int day){

        String dayTmp = "";
        Date dateNow = new Date();
        //獲取日曆
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(dateNow);
        calendar.add(Calendar.DAY_OF_MONTH,-day);
        Date dateBefore=calendar.getTime();
        //轉換格式
        SimpleDateFormat df = new SimpleDateFormat("yyyyMMddHHmmss");
        String beforeDay = df.format(dateBefore);
        //賦值
        dayTmp = beforeDay;
        System.out.println("前day天時間:"+dayTmp);
        return dayTmp;
    }