Java基礎之SimpleDateFormat和GregorianCalendar的使用

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import static java.lang.System.*;

/**
 * Created by leo on 17-7-11.
 * GregorianCalendar默認以當前日期構建一個GregorianCalendar對象
 * 可以獲得年月日，時分秒等信息
 * 更多操作參考java官方API
 *
 *
 下面的內容有如下格式：Letter	  Date or Time Component	  Presentation	  Examples
 G	Era designator	Text	AD
 y	Year	Year	1996; 96
 Y	Week year	Year	2009; 09
 M	Month in year (context sensitive)	Month	July; Jul; 07
 L	Month in year (standalone form)	Month	July; Jul; 07
 w	Week in year	Number	27
 W	Week in month	Number	2
 D	Day in year	Number	189
 d	Day in month	Number	10
 F	Day of week in month	Number	2
 E	Day name in week	Text	Tuesday; Tue
 u	Day number of week (1 = Monday, ..., 7 = Sunday)	Number	1
 a	Am/pm marker	Text	PM
 H	Hour in day (0-23)	Number	0
 k	Hour in day (1-24)	Number	24
 K	Hour in am/pm (0-11)	Number	0
 h	Hour in am/pm (1-12)	Number	12
 m	Minute in hour	Number	30
 s	Second in minute	Number	55
 S	Millisecond	Number	978
 z	Time zone	General time zone	Pacific Standard Time; PST; GMT-08:00
 Z	Time zone	RFC 822 time zone	-0800
 X	Time zone	ISO 8601 time zone	-08; -0800; -08:00
 */
public class GregorianCalendarNote {
    public static void main(String[] args){
//        GregorianCalendar exetends Calendar
        Calendar cal = new GregorianCalendar();

        out.println(cal);
        out.println(cal.getFirstDayOfWeek());
        out.println(cal.getTimeZone());
        out.println(cal.get(Calendar.YEAR));
        out.println(cal.get(Calendar.MONTH + 1));
        out.println(cal.get(Calendar.DAY_OF_MONTH));
        out.println(cal.get(Calendar.HOUR));
        out.println(cal.get(Calendar.MINUTE));
        out.println(cal.get(Calendar.SECOND));
        out.println(cal.get(Calendar.DAY_OF_YEAR));
        out.println(cal.getTime());
        cal.set(2012,12,2);

        SimpleDateFormat format1 = new SimpleDateFormat("yyyy:MM:dd HH:mm:ss");
        SimpleDateFormat format2 = new SimpleDateFormat("yyyy年MM月dd日 HH時mm分ss秒 E ");
        SimpleDateFormat format3 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//等價於now.toLocaleString()
        SimpleDateFormat format4 = new SimpleDateFormat("一年中的第 D 天 一年中第w個星期 一月中第W個星期 在一天中k時 z時區");

        Date now = new Date();
        out.println(format1.format(now));
        out.println(format2.format(now));
        out.println(format3.format(now));
        out.println(now.toLocaleString());
        out.println(format4.format(now));


    }

}
/*  結果如下
java.util.GregorianCalendar[time=1499737898037,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Shanghai",offset=28800000,dstSavings=0,useDaylight=false,transitions=19,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2017,MONTH=6,WEEK_OF_YEAR=28,WEEK_OF_MONTH=3,DAY_OF_MONTH=11,DAY_OF_YEAR=192,DAY_OF_WEEK=3,DAY_OF_WEEK_IN_MONTH=2,AM_PM=0,HOUR=9,HOUR_OF_DAY=9,MINUTE=51,SECOND=38,MILLISECOND=37,ZONE_OFFSET=28800000,DST_OFFSET=0]
1
sun.util.calendar.ZoneInfo[id="Asia/Shanghai",offset=28800000,dstSavings=0,useDaylight=false,transitions=19,lastRule=null]
2017
28
11
9
51
38
192
Tue Jul 11 09:51:38 CST 2017
2017:07:11 09:51:38
2017年07月11日 09時51分38秒 Tue
2017-07-11 09:51:38
Jul 11, 2017 9:51:38 AM
一年中的第 192 天 一年中第28個星期 一月中第3個星期 在一天中9時 CST時區
 */