Java 时间格式处理

2023-02-01 10:12:13

jdk里面的日期格式处理使用SimpleDateFormat,这个类其实也是在内部调用的Calendar

Calendar概念比较负责，涉及到时区和本地化

看一些简单的demo:

package com.qhong;

import java.text.DateFormat;

import java.text.SimpleDateFormat;

import java.util.Calendar;

import java.util.Date;

public class Main {

    public static void main(String[] args) throws Exception {

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

        System.out.println(df.format(new Date()));

        Calendar calendar=Calendar.getInstance();

        Date dt=calendar.getTime();

        System.out.println(df.format(dt));

        System.out.println(calendar.getWeekYear());

        System.out.println(calendar.getFirstDayOfWeek());

        System.out.println(calendar.getWeeksInWeekYear());

        System.out.println("====================");

        System.out.println(calendar.get(Calendar.YEAR));

        System.out.println(calendar.get(Calendar.MONTH));

        System.out.println(calendar.get(Calendar.DAY_OF_MONTH));

        System.out.println(calendar.get(Calendar.DAY_OF_WEEK));

        System.out.println(calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));

        System.out.println(calendar.get(Calendar.DAY_OF_YEAR));

        System.out.println("====================");

        System.out.println(calendar.get(Calendar.DATE));

        System.out.println(calendar.get(Calendar.HOUR));

        System.out.println(calendar.get(Calendar.HOUR_OF_DAY));

        System.out.println(calendar.get(Calendar.MINUTE));

        System.out.println(calendar.get(Calendar.SECOND));

        System.out.println("====================");

        System.out.println(calendar.get(Calendar.MILLISECOND));

        Calendar NewCalendar=Calendar.getInstance();

        NewCalendar.setTime(new Date());

        System.out.println(df.format(NewCalendar.getTime()));

        NewCalendar.add(Calendar.YEAR,-1);

        System.out.println(df.format(NewCalendar.getTime()));

        NewCalendar.add(Calendar.MONTH,2);

        System.out.println(df.format(NewCalendar.getTime()));

        NewCalendar.add(Calendar.DATE,3);

        //后者大，显示 -1

        System.out.println(df.format(NewCalendar.getTime()));

        System.out.println("时间比较："+NewCalendar.compareTo(calendar));

        //前者大，显示 1

        NewCalendar.add(Calendar.YEAR,1);

        System.out.println("时间比较："+NewCalendar.compareTo(calendar));

    }

}

2017-03-13 22:36:08:393

2017-03-13 22:36:08:394

2017

1

52

====================

2017

2

13

2

2

72

====================

13

10

22

36

8

====================

394

2017-03-13 22:36:08:394

2016-03-13 22:36:08:394

2016-05-13 22:36:08:394

2016-05-16 22:36:08:394

时间比较：-1

时间比较：1

比较好的第三方解决方案：joda-time

         <dependency>

            <groupId>joda-time</groupId>

            <artifactId>joda-time</artifactId>

            <version>2.9.9</version>

        </dependency>

最简单的demo:

package com.qhong;

import org.joda.time.DateTime;

import org.joda.time.format.DateTimeFormat;

import org.joda.time.format.DateTimeFormatter;

import java.util.Date;

public class Main {

    public static void main(String[] args) {

        Date now=new Date();

        DateTime dt=new DateTime(now);

        System.out.println(dt.toString("yyyy-MM-dd HH:mm:ss"));

        String str="2017-08-15 12:12:22";

        DateTimeFormatter format = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss");

        DateTime dt2=format.parseDateTime(str);

        DateTime dt3=DateTime.parse(str,format);

        System.out.println(dt2.equals(dt3));

        System.out.println(dt2.toString("yyyy-MM-dd HH:mm:ss"));

    }

}

Output:

2017-08-06 22:14:15

true

2017-08-15 12:12:22

复杂的demo:

package com.qhong;

import org.joda.time.DateTime;

import org.joda.time.Days;

import org.joda.time.LocalDate;

import org.joda.time.format.DateTimeFormat;

import org.joda.time.format.DateTimeFormatter;

import java.util.Calendar;

import java.util.Date;

import java.util.Locale;

public class Main {

    public static void main(String[] args) {

        //初始化时间

        DateTime dateTime=new DateTime(2017, 8, 6, 20, 34,55);

        //下面就是按照一点的格式输出时间

        String str2 = dateTime.toString("MM/dd/yyyy hh:mm:ss.SSSa");

        String str3 = dateTime.toString("dd-MM-yyyy HH:mm:ss");

        String str4 = dateTime.toString("EEEE dd MMMM, yyyy HH:mm:ssa");

        String str5 = dateTime.toString("MM/dd/yyyy HH:mm ZZZZ");

        String str6 = dateTime.toString("MM/dd/yyyy HH:mm Z");

        System.out.println(str2);

        System.out.println(str3);

        System.out.println(str4);

        System.out.println(str5);

        System.out.println(str6);

        System.out.println(dateTime.toString("yyyy-MM-dd HH:mm:ss"));

        System.out.println("==========================");

        DateTimeFormatter format = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss");

        //时间解析

        DateTime dateTime2 = DateTime.parse("2012-12-21 23:22:45", format);

        //时间格式化，输出==> 2012/12/21 23:22:45 Fri

        String string_u = dateTime2.toString("yyyy/MM/dd HH:mm:ss EE");

        System.out.println(string_u);

        //格式化带Locale，输出==> 2012年12月21日 23:22:45 星期五

        String string_c = dateTime2.toString("yyyy年MM月dd日 HH:mm:ss EE", Locale.CHINESE);

        System.out.println(string_c);

        DateTime dt1 = new DateTime();// 取得当前时间

        // 根据指定格式,将时间字符串转换成DateTime对象,这里的格式和上面的输出格式是一样的

        DateTime dt2 = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss").parseDateTime("2012-12-26 03:27:39");

        //计算两个日期间隔的天数

        LocalDate start=new LocalDate(2012, 12,14);

        LocalDate end=new LocalDate(2013, 01, 15);

        int days = Days.daysBetween(start, end).getDays();

        //计算两个日期间隔的小时数,分钟数,秒数

        //增加日期

        DateTime dateTime1 = DateTime.parse("2012-12-03");

        dateTime1 = dateTime1.plusDays(30);

        dateTime1 = dateTime1.plusHours(3);

        dateTime1 = dateTime1.plusMinutes(3);

        dateTime1 = dateTime1.plusMonths(2);

        dateTime1 = dateTime1.plusSeconds(4);

        dateTime1 = dateTime1.plusWeeks(5);

        dateTime1 = dateTime1.plusYears(3);

        // Joda-time 各种操作.....

        dateTime = dateTime.plusDays(1) // 增加天

                .plusYears(1)// 增加年

                .plusMonths(1)// 增加月

                .plusWeeks(1)// 增加星期

                .minusMillis(1)// 减分钟

                .minusHours(1)// 减小时

                .minusSeconds(1);// 减秒数

        //判断是否闰月

        DateTime dt4 = new DateTime();

        org.joda.time.DateTime.Property month = dt4.monthOfYear();

        System.out.println("是否闰月:" + month.isLeap());

        //取得 3秒前的时间

        DateTime dt5 = dateTime1.secondOfMinute().addToCopy(-3);

        dateTime1.getSecondOfMinute();// 得到整分钟后，过的秒钟数

        dateTime1.getSecondOfDay();// 得到整天后，过的秒钟数

        dateTime1.secondOfMinute();// 得到分钟对象,例如做闰年判断等使用

        // DateTime与java.util.Date对象,当前系统TimeMillis转换

        DateTime dt6 = new DateTime(new Date());

        Date date = dateTime1.toDate();

        DateTime dt7 = new DateTime(System.currentTimeMillis());

        dateTime1.getMillis();

        Calendar calendar = Calendar.getInstance();

        dateTime = new DateTime(calendar);

    }

}

Output:

08/06/2017 08:34:55.000下午

06-08-2017 20:34:55

星期日 06 八月, 2017 20:34:55下午

08/06/2017 20:34 Asia/Shanghai

08/06/2017 20:34 +0800

2017-08-06 20:34:55

==========================

2012/12/21 23:22:45 星期五

2012年12月21日 23:22:45 星期五

是否闰月:false

比SimpleDataFormat简单多了

http://blog.csdn.net/joyous/article/details/9630893

http://sunnyhl.iteye.com/blog/1205820

http://www.cnblogs.com/peida/archive/2013/05/31/3070790.html

http://ylq365.iteye.com/blog/1769680

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