Java时间处理

/* * 时间表达方式有三种：long、Date、Calendar */long timer=System.currentTimeMillis();int year=(int) (timer/1000/60/60/24/365)+1970;System.out.println(year);//Date date=new Date(timer);Date date=new Date();System.out.println(date.getYear()+1900);System.out.println(date.getMonth());//历法：Calendar//GregorianCalendar():公元纪年；公历Calendar calendar=new GregorianCalendar();//calendar.setTime(date);year=calendar.get(Calendar.YEAR);int month=calendar.get(Calendar.MONTH)+1;int day=calendar.get(Calendar.DAY_OF_MONTH);int hour=calendar.get(Calendar.HOUR);int minute=calendar.get(Calendar.MINUTE);int second=calendar.get(Calendar.SECOND);System.out.println(year+"-"+month+"-"+day+" "+hour+":"+minute+":"+second);/* * long---->Date */date=new Date(timer);date.setTime(timer);/* * Date---->long */timer=date.getTime();/* * Date---->Calendar */calendar.setTime(date);/* * Calendar---->Date */calendar.getTime();/* * yyyy/MM/dd HH:mm:ss 大H24小时格式 * yyyy/MM/dd hh:mm:ss 小h24小时格式 */DateFormat fm=new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");String str=fm.format(date);System.out.println(str);SimpleDateFormat fmt=new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");Date date1=fmt.parse(str);str="2013/2/16 10:32:54";date1=fmt.parse(str);calendar.setTime(date1);calendar.add(calendar.MONTH, 6);calendar.add(calendar.WEEK_OF_YEAR, -2);calendar.set(calendar.DAY_OF_WEEK, Calendar.SUNDAY);date1=calendar.getTime();str=fmt.format(date1);System.out.println(str);