日历的一些使用方法

把日期转换为字符串:

Date date = new Date();

System.out.println(date);

java.text.DateFormat df = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

String s = df.format(date);

System.out.println(s);

把字符串转换为日期

String s2 = "19960245"; // yyyyMMdd

java.text.DateFormat df2 = new java.text.SimpleDateFormat("yyyyMMdd");

Date date2 = df2.parse(s2);

System.out.println(date2);

日历的相关方法的一些使用

		 DateFormat dateFormat1 = DateFormat.getDateInstance(DateFormat.FULL);
		 Calendar calendar =  Calendar.getInstance();
		 
		 Date trialTime = new Date();
		 calendar.setTime(trialTime);
		 calendar.setFirstDayOfWeek(Calendar.MONDAY);//设置一周的第一天是星期一
		 // print out a bunch of interesting things
		 System.out.println("ERA: " + calendar.get(Calendar.ERA));
		 System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
		 System.out.println("MONTH: " + calendar.get(Calendar.MONTH));
		 System.out.println("WEEK_OF_YEAR: " + calendar.get(Calendar.WEEK_OF_YEAR));
		 System.out.println("WEEK_OF_MONTH: " + calendar.get(Calendar.WEEK_OF_MONTH));
		 System.out.println("DATE: " + calendar.get(Calendar.DATE));
		 System.out.println("DAY_OF_MONTH: " + calendar.get(Calendar.DAY_OF_MONTH));
		 System.out.println("DAY_OF_YEAR: " + calendar.get(Calendar.DAY_OF_YEAR));
		 System.out.println("DAY_OF_WEEK: " + calendar.get(Calendar.DAY_OF_WEEK));
		 System.out.println("System Date: " + dateFormat1.format(calendar.getTime()));

		// 这样的话就对了！
		int week = 3;
		Date mDate = new Date();
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		try {
			mDate = sdf.parse(mDate.toString());
		} catch (java.text.ParseException pe) {
		}

		Calendar cld = Calendar.getInstance();//使用默认时区和语言环境获得一个日历。
		cld.setFirstDayOfWeek(Calendar.MONDAY);//设置一周的第一天是星期一
		cld.setTime(mDate);
		int i = cld.get(Calendar.WEEK_OF_MONTH);
		System.out.println("this is the " + i + " week!");

		//DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.FULL);
		DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
		GregorianCalendar cal = new GregorianCalendar();
		cal.setTime(mDate);
		System.out.println("System Date: " + dateFormat.format(cal.getTime()));

		cal.set(GregorianCalendar.DAY_OF_WEEK, GregorianCalendar.MONDAY);
		System.out.println("After Setting Day of Week to Monday: "
				+ dateFormat.format(cal.getTime()));
		cal.add(GregorianCalendar.DAY_OF_MONTH, -1);
		System.out.println("日期:" + dateFormat.format(cal.getTime()));
		cal.add(GregorianCalendar.DAY_OF_MONTH, -1);
		System.out.println("日期:" + dateFormat.format(cal.getTime()));
		cal.add(GregorianCalendar.DAY_OF_MONTH, -14);
		System.out.println("当前日期的前14天是:" + dateFormat.format(cal.getTime()));
		cal.add(GregorianCalendar.DAY_OF_MONTH, 7 * (week - 1));
		System.out.println("日期" + dateFormat.format(cal.getTime()));
		cal.add(GregorianCalendar.DAY_OF_MONTH, 6);
		System.out.println("日期" + dateFormat.format(cal.getTime()));
		
		DateFormat dateFormat2 = new SimpleDateFormat("yyyy-MM-dd");
		GregorianCalendar cal2 = new GregorianCalendar();
		cal2.setTime(mDate);
		System.out.println("System Date: " + dateFormat2.format(cal2.getTime()));
		cal2.set(GregorianCalendar.DAY_OF_WEEK, GregorianCalendar.SUNDAY);
		System.out.println("sunday Setting Day of Week to Monday: "
				+ dateFormat.format(cal2.getTime()));
		cal2.add(GregorianCalendar.DAY_OF_MONTH, 1);
		System.out.println("日期:" + dateFormat.format(cal2.getTime()));
		cal2.add(GregorianCalendar.DAY_OF_MONTH, 1);
		System.out.println("日期:" + dateFormat.format(cal2.getTime()));

输出结果:

ERA: 1
YEAR: 2010
MONTH: 9
WEEK_OF_YEAR: 44
WEEK_OF_MONTH: 5
DATE: 25
DAY_OF_MONTH: 25
DAY_OF_YEAR: 298
DAY_OF_WEEK: 2
System Date: 2010年10月25日 星期一
this is the 5 week!
System Date: 2010-10-25
After Setting Day of Week to Monday: 2010-10-25
日期:2010-10-24
日期:2010-10-23
当前日期的前14天是:2010-10-09
日期2010-10-23
日期2010-10-29
System Date: 2010-10-25
sunday Setting Day of Week to Monday: 2010-10-24
日期:2010-10-25
日期:2010-10-26