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);