两个日期相关的方法

1、计算两个日期之间的分钟数：

Calendar calendar = Calendar.getInstance();
		calendar.setTime(new Date());
		System.out.println(calendar.getTimeInMillis());
		
		SimpleDateFormat d = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Date ds = d.parse("2013-12-12 12:12:12");
		Date d2 = d.parse("2013-12-12 12:15:12");
		System.out.println((d2.getTime()-ds.getTime())/60/1000);

 2、比较两个日期

String s1 = "2013-01-12 12:01:01";
		Date date = new Date();
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Calendar c1 = Calendar.getInstance();
		Calendar c2 = Calendar.getInstance();
		try {
			c1.setTime(sdf.parse(s1));
			c2.setTime(date);
			System.out.println(c1.compareTo(c2));
                         //输出-1，说明给点时间早于当前时间，若是1则表示大于当前时间
		} catch (ParseException e) {
			e.printStackTrace();
		}