Java 如何获取当前时间前一个小时的时间

public?static?void?beforeOneHourToNowDate()?{??????????Calendar?calendar?=?Calendar.getInstance();????????????????????/*?HOUR_OF_DAY?指示一天中的小时?*/??????????calendar.set(Calendar.HOUR_OF_DAY,?calendar.get(Calendar.HOUR_OF_DAY)?-?1);????????????????????SimpleDateFormat?df?=?new?SimpleDateFormat("yyyy-MM-dd?HH:mm:ss");????????????????????System.out.println("一个小时前的时间："?+?df.format(calendar.getTime()));??????????System.out.println("当前的时间："?+?df.format(new?Date()));??}?