Calendar日历类

Calendar类是一个抽象类，为我们提供了关于计算的功能，比如：年、月、日
时、分、秒的展示和计算。
GregorianCalendar是Calendar的子类，表示公历
菜鸟雷区
注意月份的表示，一月是0，二月是1，以此类推，12是11.因为大多数人习惯于
使用单词而不是使用数字来表示月份，这样程序也许更易读，父类Calendar使用
常量来表示月份：JANUARY,FEBRUARYD等等。

package com.itbaizhan;
import java.util.*;
//测试DateFormat
public class TestDateFormat {
    public static void main(String[] args) {
        GregorianCalendar calendar=new GregorianCalendar
                (2049,9,1,22,10,50);
        //System.out.println(calendar);
        printCalendar(calendar);
        int year =calendar.get(Calendar.YEAR);
        //打印：2049
        int month=calendar.get(Calendar.MONTH);
        //打印：10
        int day=calendar.get(Calendar.DAY_OF_MONTH);
        //打印10
        int day2=calendar.get(Calendar.DATE);
        //打印9
        //日：Calendar.DATE和Calendar.DAY_OF_MONTH同义
        int date=calendar.get(Calendar.DAY_OF_WEEK);
        //打印3
        //星期几 这里是：1-7.周日是1，周一是2   周六是7
        System.out.println(year);
        System.out.println(month);
        System.out.println(day);
        System.out.println(day2);
        System.out.println(date);
        GregorianCalendar calendar2=new GregorianCalendar();
        calendar2.set(Calendar.YEAR,2049);
        calendar2.set(Calendar.MONTH,Calendar.OCTOBER);
        //月份0-11
        calendar2.set(Calendar.DATE,1);
        calendar2.set(Calendar.HOUR_OF_DAY,10);
        calendar2.set(Calendar.MINUTE,20);
        calendar2.set(Calendar.SECOND,23);
        printCalendar(calendar2);
        GregorianCalendar calendar3=new GregorianCalendar
                (2049,9,1,22,10,50);
        calendar3.add(Calendar.MONTH,-7);
        calendar3.add(Calendar.DATE,7);
        printCalendar(calendar3);
        GregorianCalendar calendar4=new GregorianCalendar();
        calendar4.setTime(new Date());
        printCalendar(calendar4);
    }
    static void printCalendar(Calendar calendar) {
        int year=calendar.get(Calendar.YEAR);
        int month=calendar.get(Calendar.MONTH)+1;
        int day=calendar.get(Calendar.DAY_OF_MONTH);
        int date=calendar.get(Calendar.DAY_OF_WEEK)-1;
        //星期几
        String week=""+((date==0)?"日":date);
        int hour=calendar.get(Calendar.HOUR);
        int minute=calendar.get(Calendar.MINUTE);
        int second= calendar.get(Calendar.SECOND);
        System.out.println(year+"年"+month+"月"+day+"日"+"星期"+week+"  "+hour+"时"+minute+"分"+second+"秒");
        //System.out.println("%d年%d月%d日,星期%s %d:%d:%d\n", year,month,day,week,hour,minute,second);
    }
}