java获取当前某个时间点

private String getTime(String flag, int times) {
		String time = new String();
		SimpleDateFormat startDf = new SimpleDateFormat("yyyy-MM-dd 00:00:00");
    	SimpleDateFormat endDf = new SimpleDateFormat("yyyy-MM-dd 23:59:59");
    	Calendar cal=Calendar.getInstance();
    	if (times == 2) {
    		cal.add(Calendar.MONTH, -2);    //得到前两个月
    	} else if (times == 6) {
    		cal.add(Calendar.MONTH, -6);    //得到前六个月
    	} else {
    		cal.add(Calendar.MONTH, -1);    //得到前一个月
    	}
       
        long l_date = cal.getTimeInMillis();
        Date date=new Date(l_date);
        if (flag.equals("start")) {
        	time = startDf.format(date);
        } else {
        	time = endDf.format(new Date());
        }
        
		return time;
	}