JAVA获取当前时间的前一天或者前几天时间

                SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Date date=new Date();
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(date);
		calendar.add(Calendar.DAY_OF_MONTH, -1);
		date = calendar.getTime();
		System.out.println(sdf.format(date));