java获得指定时间的前几天或后几天是哪一天

    public static Date daysAgoOrAfter(Date oneday,int amount){
		Calendar mon = Calendar.getInstance();
		mon.setTime(oneday);
		mon.add(Calendar.DATE,amount);
		return mon.getTime();
	}

注：前几天参数amount为负整数

       后几天参数amount为正整数

    public static void main(String[] args){
		String s="2022-04-25";
		Date date = DateUtils.parseDate(s);
		System.err.println("7天之前");
		System.err.println(daysAgoOrAfter(date,-7));
		System.err.println("6天之后");
		System.err.println(daysAgoOrAfter(date,6));
	}

结果输出：