public static void main(String[] args) {SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");Calendar calendar = Calendar.getInstance();//现在日期String now = format.format(new Date());System.out.println("现在日期  ："+now);//过去七天calendar.setTime(new Date());calendar.add(Calendar.DATE, - 7);Date d = calendar.getTime();String day = format.format(d);System.out.println("过去七天  ："+day);//过去一月calendar.setTime(new Date());calendar.add(Calendar.MONTH, -1);Date m = calendar.getTime();String mon = format.format(m);System.out.println("过去一个月："+mon);//过去三个月calendar.setTime(new Date());calendar.add(Calendar.MONTH, -3);Date m3 = calendar.getTime();String mon3 = format.format(m3);System.out.println("过去三个月："+mon3);//过去一年calendar.setTime(new Date());calendar.add(Calendar.YEAR, -1);Date y = calendar.getTime();String year = format.format(y);System.out.println("过去一年  ："+year);}