java获取当前年月日时间戳_现在的年月日怎么来的

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;

import org.junit.Test;


public class GetTimeNow {

	/**
	 * 通过Calendar类获取
	 */
	@Test
	public void getTimeNowThroughCalendar(){
		//使用默认时区和语言环境获得一个日历。
		Calendar    rightNow    =    Calendar.getInstance();   
		/*用Calendar的get(int field)方法返回给定日历字段的值。
		HOUR 用于 12 小时制时钟 (0 - 11)，HOUR_OF_DAY 用于 24 小时制时钟。*/
		Integer year = rightNow.get(Calendar.YEAR); 
		Integer month = rightNow.get(Calendar.MONTH)+1; //第一个月从0开始，所以得到月份＋1
		Integer day = rightNow.get(rightNow.DAY_OF_MONTH);
		Integer hour12 = rightNow.get(rightNow.HOUR); 
		Integer hour24 = rightNow.get(rightNow.HOUR_OF_DAY);
		Integer minute = rightNow.get(rightNow.MINUTE);
		Integer second = rightNow.get(rightNow.SECOND);
		Integer millisecond = rightNow.get(rightNow.MILLISECOND);
		String TimeNow12 = year+"-"+month+"-"+day+" "+hour12+":"+minute+":"+second+":"+millisecond;
		String TimeNow24 = year+"-"+month+"-"+day+" "+hour24+":"+minute+":"+second+":"+millisecond;
		 System.out.println("日历："+rightNow+"\n12小时制时钟："+TimeNow12+"\n24小时制时钟："+TimeNow24);
	}
	
	/**
	 * 通过Date类获取
	 */
	@Test
	public void getTimeNowThroughDate(){
		Date date=new Date();
		DateFormat format=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SS");
		System.out.println(format.format(date));
		//DateFormat类的静态工厂方法
		System.out.println(format.getInstance().format(date));
		System.out.println(format.getDateInstance().format(date));
		System.out.println(format.getTimeInstance().format(date));
		System.out.println(format.getDateTimeInstance().format(date));
		
		//DateFormat带参数的静态工厂方法
		//第一个参数是静态变量style有4中取值0、1、2、3分别对应SHORT、MIDIUM、LONG、FULL
		//第二个参数根据环境敏感的Locale类的静态变量自定义输出
		System.out.println(format.getDateInstance(0, Locale.CHINA).format(date)); 
		System.out.println(format.getTimeInstance(0,Locale.CHINA).format(date));
		
		System.out.println(format.getDateTimeInstance(2,2).format(date));  
		}
	
	/**
	 * 两者结合。。。
	 */
	@Test
	public void getTimeNowTogether(){
		String TimeNow = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SS").format(Calendar.getInstance().getTime());
		System.out.println(TimeNow);
	}
	
}

日历：java.util.GregorianCalendar[time=1454251772565,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=2016,MONTH=0,WEEK_OF_YEAR=6,WEEK_OF_MONTH=6,DAY_OF_MONTH=31,DAY_OF_YEAR=31,DAY_OF_WEEK=1,DAY_OF_WEEK_IN_MONTH=5,AM_PM=1,HOUR=10,HOUR_OF_DAY=22,MINUTE=49,SECOND=32,MILLISECOND=565,ZONE_OFFSET=28800000,DST_OFFSET=0]
12小时制时钟：2016-1-31 10:49:32:565
24小时制时钟：2016-1-31 22:49:32:565

2016-01-31 22:49:50:36
16-1-31 下午10:49
2016-1-31
22:49:50
2016-1-31 22:49:50
2016年1月31日 星期日
下午10时49分50秒 CST
2016-1-31 22:49:50

2016-01-31 22:50:09:270