4hutool practice: dateutil format time [easy to understand]

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hutool Date time series

1DateUtil( Time tools )- Current time and current timestamp

2DateUtil( Time tools )- Common time types Date,DateTime,Calendar and TemporalAccessor（LocalDateTime） transformation

3DateUtil( Time tools )- Get various contents of the date

4DateUtil( Time tools )- Format time

5DateUtil( Time tools )- Parse the formatted time

6DateUtil( Time tools )- Time offset acquisition

7DateUtil( Time tools )- Date calculation

8ChineseDate( Lunar date tool class )

9LocalDateTimeUtil(JDK8+ Medium {@link LocalDateTime} Tool class encapsulation )

10TemporalAccessorUtil{@link TemporalAccessor} Tool class encapsulation

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purpose ： Format time

Use scenarios

Format the date into the corresponding date string according to different requirements

Project reference

This blog post is based on ：hutool-5.6.5 Version source code

        <dependency>
			<groupId>cn.hutool</groupId>
			<artifactId>hutool-core</artifactId>
			<version>5.6.5</version>
		</dependency>

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Method summary

Method	describe
cn.hutool.core.date.DateUtil.formatLocalDateTime(java.time.LocalDateTime)	Format date time <br> Format yyyy-MM-dd HH:mm:ss
cn.hutool.core.date.DateUtil.format(java.time.LocalDateTime, java.lang.String)	Format the date according to a specific format
cn.hutool.core.date.DateUtil.format(java.util.Date, java.lang.String)	Format the date according to a specific format
cn.hutool.core.date.DateUtil.format(java.util.Date, cn.hutool.core.date.format.DatePrinter)	Format the date according to a specific format
cn.hutool.core.date.DateUtil.format(java.util.Date, java.text.DateFormat)	Format the date according to a specific format
cn.hutool.core.date.DateUtil.format(java.util.Date, java.time.format.DateTimeFormatter)	Format the date according to a specific format
cn.hutool.core.date.DateUtil.formatDateTime(java.util.Date)	Format date time <br> Format yyyy-MM-dd HH:mm:ss
cn.hutool.core.date.DateUtil.formatDate(java.util.Date)	Format date section （ Not including time ）<br> Format yyyy-MM-dd
cn.hutool.core.date.DateUtil.formatTime(java.util.Date)	Format time <br> Format HH:mm:ss
cn.hutool.core.date.DateUtil.formatHttpDate(java.util.Date)	Formatted as Http Standard date format for <br> The standard date format follows RFC 1123 standard , The format is similar to ：Fri, 31 Dec 1999 23:59:59 GMT
cn.hutool.core.date.DateUtil.formatChineseDate(java.util.Date, boolean, boolean)	Format as Chinese date format , If isUppercase by false, Returns something like ：2018 year 10 month 24 Japan , Otherwise, it returns two 〇 October 24, 2018

Method details

Method name :cn.hutool.core.date.DateUtil.formatLocalDateTime(java.time.LocalDateTime)

Methods described

Format date time <br> Format yyyy-MM-dd HH:mm:ss

Support version and above

Parameters to describe :

Parameter name	describe
LocalDateTime localDateTime	localDateTime Formatted date

Return value :

Formatted string

Reference cases :

        String strDate = "2019-12-01 17:02:30";
		LocalDateTime ldt = DateUtil.parseLocalDateTime(strDate);
		String strDate1 = DateUtil.formatLocalDateTime(ldt);
		Assert.assertEquals(strDate, strDate1);

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.format(java.time.LocalDateTime, java.lang.String)

Methods described

Format the date according to a specific format

Support version and above

Parameters to describe :

Parameter name	describe
LocalDateTime localDateTime	localDateTime Formatted date
String format	format Date format , For common formats, see ： {@link DatePattern}

Return value :

Formatted string

Reference cases :

		String strDate2 = "2019-12-01 17:02:30.111";
		ldt = DateUtil.parseLocalDateTime(strDate2, DatePattern.NORM_DATETIME_MS_PATTERN);
		strDate1 = DateUtil.format(ldt, DatePattern.NORM_DATETIME_PATTERN);
		Assert.assertEquals(strDate, strDate1);

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.format(java.util.Date, java.lang.String)

Methods described

Format the date according to a specific format

Support version and above

Parameters to describe :

Parameter name	describe
Date date	date Formatted date
String format	format Date format , For common formats, see ： {@link DatePattern}

Return value :

Formatted string

Reference cases :

		String strDate = "2021-05-16";
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		Date localDate = sdf.parse(strDate);
		Assert.assertEquals(strDate, DateUtil.format(localDate, DatePattern.NORM_DATE_PATTERN));

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.format(java.util.Date, cn.hutool.core.date.format.DatePrinter)

Methods described

Format the date according to a specific format

Support version and above

Parameters to describe :

Parameter name	describe
Date date	date Formatted date
DatePrinter format	format {@link DatePrinter} or {@link FastDateFormat}

Return value :

Formatted string

Reference cases :

		// Format the date according to a specific format 
		String str = "2021-05-16";
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd", Locale.US);
		Date date = DateUtil.parse(str);
		String dateStr = DateUtil.format(date,sdf);
		System.out.println(dateStr);
		Assert.assertEquals(str, dateStr);

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.format(java.util.Date, java.text.DateFormat)

Methods described

Format the date according to a specific format

Support version and above

Parameters to describe :

Parameter name	describe
Date date	date Formatted date
DateFormat format	format {@link SimpleDateFormat}

Return value :

Formatted string

Reference cases :

 To be added 

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.format(java.util.Date, java.time.format.DateTimeFormatter)

Methods described

Format the date according to a specific format

Support version and above

5.0.0

Parameters to describe :

Parameter name	describe
Date date	date Formatted date
DateTimeFormatter format	format {@link SimpleDateFormat}

Return value :

Formatted string

Reference cases :

		// Format the date according to a specific format 
		String str = "2021-05-16";
		DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd", Locale.US);
		Date date = DateUtil.parse(str);
		String dateStr = DateUtil.format(date,dtf);
		System.out.println(dateStr);
		Assert.assertEquals(str, dateStr);
		//  There is a problem with this method , Officially processed   The processing version is 5.7.5  Repair  
		java.time.temporal.UnsupportedTemporalTypeException: Unsupported field: YearOfEra

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.formatDateTime(java.util.Date)

Methods described

Format date time <br> Format yyyy-MM-dd HH:mm:ss

Support version and above

Parameters to describe :

Parameter name	describe
Date date	date Formatted date

Return value :

Formatted date

Reference cases :

		String dateStr = "2017-03-01";
		Date date = DateUtil.parse(dateStr);

		String format = DateUtil.format(date, "yyyy/MM/dd");
		Assert.assertEquals("2017/03/01", format);

		//  Format of common formats 
		String formatDate = DateUtil.formatDate(date);
		Assert.assertEquals("2017-03-01", formatDate);
		String formatDateTime = DateUtil.formatDateTime(date);
		Assert.assertEquals("2017-03-01 00:00:00", formatDateTime);
		String formatTime = DateUtil.formatTime(date);
		Assert.assertEquals("00:00:00", formatTime);

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.formatDate(java.util.Date)

Methods described

Format date section （ Not including time ）<br> Format yyyy-MM-dd

Support version and above

Parameters to describe :

Parameter name	describe
Date date	date Formatted date

Return value :

Formatted string

Reference cases :

		String dateStr = "2017-03-01";
		Date date = DateUtil.parse(dateStr);

		String format = DateUtil.format(date, "yyyy/MM/dd");
		Assert.assertEquals("2017/03/01", format);

		//  Format of common formats 
		String formatDate = DateUtil.formatDate(date);
		Assert.assertEquals("2017-03-01", formatDate);
		String formatDateTime = DateUtil.formatDateTime(date);
		Assert.assertEquals("2017-03-01 00:00:00", formatDateTime);
		String formatTime = DateUtil.formatTime(date);
		Assert.assertEquals("00:00:00", formatTime);

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.formatTime(java.util.Date)

Methods described

Format time <br> Format HH:mm:ss

Support version and above

3.0.1

Parameters to describe :

Parameter name	describe
Date date	date Formatted date

Return value :

Formatted string

Reference cases :

		String dateStr = "2017-03-01";
		Date date = DateUtil.parse(dateStr);

		String format = DateUtil.format(date, "yyyy/MM/dd");
		Assert.assertEquals("2017/03/01", format);

		//  Format of common formats 
		String formatDate = DateUtil.formatDate(date);
		Assert.assertEquals("2017-03-01", formatDate);
		String formatDateTime = DateUtil.formatDateTime(date);
		Assert.assertEquals("2017-03-01 00:00:00", formatDateTime);
		String formatTime = DateUtil.formatTime(date);
		Assert.assertEquals("00:00:00", formatTime);

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.formatHttpDate(java.util.Date)

Methods described

Formatted as Http Standard date format for <br> The standard date format follows RFC 1123 standard , The format is similar to ：Fri, 31 Dec 1999 23:59:59 GMT

Support version and above

Parameters to describe :

Parameter name	describe
Date date	date Formatted date

Return value :

HTTP Standard form date string

Reference cases :

        String formatHttpDate = DateUtil.formatHttpDate(DateUtil.parse("2019-01-02 22:32:01"));
		Assert.assertEquals("Wed, 02 Jan 2019 14:32:01 GMT", formatHttpDate);

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

Method details

Method name :cn.hutool.core.date.DateUtil.formatChineseDate(java.util.Date, boolean, boolean)

Methods described

Format as Chinese date format , If isUppercase by false, Returns something like ：2018 year 10 month 24 Japan , Otherwise, it returns two 〇 October 24, 2018

Support version and above

5.3.9

Parameters to describe :

Parameter name	describe
Date date	date Formatted date
boolean isUppercase	isUppercase Whether in uppercase
boolean withTime	withTime Whether to include the time part

Return value :

Chinese date string

Reference cases :

        String formatChineseDate = DateUtil.formatChineseDate(DateUtil.parse("2018-02-24"), true, false);
		Assert.assertEquals(" Two 〇 February 24, 2018 ", formatChineseDate);

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The source code parsing ：

4hutool Source code analysis ：DateUtil( Time tools )- Format time ( Wanzi long text source code analysis , Learn how big guys write code )

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