java获得指定时间几天前或几天后的日期

/**
* 得到几天前的时间
*
* @param d
* @param day
* @return
*/
public static Date getDateBefore(Date d, int day) {
Calendar now = Calendar.getInstance();
now.setTime(d);
now.set(Calendar.DATE, now.get(Calendar.DATE) - day);
return now.getTime();
}

/**
* 得到几天后的时间
*
* @param d
* @param day
* @return
*/
public static Date getDateAfter(Date d, int day) {
Calendar now = Calendar.getInstance();
now.setTime(d);
now.set(Calendar.DATE, now.get(Calendar.DATE) + day);
return now.getTime();
}