SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");        Calendar c = Calendar.getInstance();                 //过去七天        c.setTime(new Date());        c.add(Calendar.DATE, - 7);        Date d = c.getTime();        String day = format.format(d);        System.out.println("过去七天："+day);                 //过去一月        c.setTime(new Date());        c.add(Calendar.MONTH, -1);        Date m = c.getTime();        String mon = format.format(m);        System.out.println("过去一个月："+mon);                 //过去三个月        c.setTime(new Date());        c.add(Calendar.MONTH, -3);        Date m3 = c.getTime();        String mon3 = format.format(m3);        System.out.println("过去三个月："+mon3);                 //过去一年        c.setTime(new Date());        c.add(Calendar.YEAR, -1);        Date y = c.getTime();        String year = format.format(y);        System.out.println("过去一年："+year);