java Calendar()和Date()日期test

代码：

package test;

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

public class test {

    public static void main(String[] args)
    {
        //使用默认时区和语言环境获得一个日历  
        Calendar cale = Calendar.getInstance();  
        System.out.println("____________________________________");
        System.out.println("打印calendar对象:");
        System.out.println(cale);
        //将Calendar类型转换成Date类型  
        Date tasktime=cale.getTime();  
        //设置日期输出的格式  
        System.out.println("将Calendar类型转换成Date类型，格式化输出后打印:");
        SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
        //格式化输出  
        String nowTime = df.format(tasktime);
        System.out.println(nowTime);

        int year = cale.YEAR;
        int month = cale.MONTH+1;
        int day = cale.DAY_OF_MONTH;
        System.out.println("cale.YEAR,cale.MONTH,cale.DAY_OF_MONTH 分别为:"+year+","+month+","+day+",");
        System.out.println("____________________________________");
        System.out.println("calendar.get(常量)test:");
        int y = cale.get(cale.YEAR);
        int m = cale.get(cale.MONTH)+1;
        int d = cale.get(cale.DAY_OF_MONTH);
        int week = cale.get(cale.WEEK_OF_MONTH)-1;
        //输出当前日期
        System.out.println(y+"年"+m+"月"+d+"日   "+"星期"+week);
        System.out.println("____________________________________");

        System.out.println("getTime()方法test:");
        Calendar c2 = Calendar.getInstance();  //创建Calendar对象
        Date date = c2.getTime();       //将calendar对象转换为Date对象
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        long time = date.getTime();
        String nowDate = sdf.format(date);      //格式化时间
        System.out.println("当前时间："+nowDate);
        System.out.println(date+"\n当前毫秒数："+time);
        Calendar c3 = Calendar.getInstance();
        c3.set(2011, 11, 11);  //设置要比较的时间
        Date date3 = c3.getTime();  //获取要比较的时间的毫秒数
        long time3 = date3.getTime();
        System.out.println(date3+"的系统时间毫秒为：\n"+time3);
        long x = time-time3;
        long dd=x/(1000*60*60*24);
        System.out.println("2011距离当前的毫秒数："+x+"\n距离当前的天数为："+dd+"天");

        System.out.println("____________________________________");
        System.out.println("Date+get()方法输出时间(已过时)：");
        Date DateTime1=new Date();
        int date_year=DateTime1.getYear()+1900;
        int date_month=DateTime1.getMonth()+1;
        int date_day=DateTime1.getDate();      
        int hours=DateTime1.getHours();
        int minutes=DateTime1.getMinutes();
        int seconds=DateTime1.getSeconds();       
        String date_time=date_year+"-"+date_month+"-"+date_day+" "+hours+":"+minutes+":"+seconds;
        System.out.println(date_time);
        System.out.println("____________________________________");


        System.out.println("Date+sdf输出时间：");
        Date DateTime2=new Date();
        SimpleDateFormat date_sdf=new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        String date_time2=date_sdf.format(DateTime2);
        System.out.println(date_time2);
    }
}

输出为:

____________________________________
打印calendar对象:
java.util.GregorianCalendar[time=1520571549226,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=2018,MONTH=2,WEEK_OF_YEAR=10,WEEK_OF_MONTH=2,DAY_OF_MONTH=9,DAY_OF_YEAR=68,DAY_OF_WEEK=6,DAY_OF_WEEK_IN_MONTH=2,AM_PM=1,HOUR=0,HOUR_OF_DAY=12,MINUTE=59,SECOND=9,MILLISECOND=226,ZONE_OFFSET=28800000,DST_OFFSET=0]
将Calendar类型转换成Date类型，格式化输出后打印:
2018-03-09 12:59:09
cale.YEAR,cale.MONTH,cale.DAY_OF_MONTH 分别为:1,3,5,
____________________________________
calendar.get(常量)test:
2018年3月9日   星期1
____________________________________
getTime()方法test:
当前时间：2018-03-09
Fri Mar 09 12:59:09 CST 2018
当前毫秒数：1520571549267
Sun Dec 11 12:59:09 CST 2011的系统时间毫秒为：
1323579549272
2011距离当前的毫秒数：196991999995
距离当前的天数为：2279天
____________________________________
Date+get()方法输出时间(已过时)：
2018-3-9 12:59:9
____________________________________
Date+sdf输出时间：
2018-03-09 12:59:09