如何使用LocalDateTime解析/格式化日期？（爪哇 8）

解析日期和时间

若要从字符串创建对象，可以使用静态 LocalDateTime.parse（） 方法。它采用字符串和 DateTimeFormatter 作为参数。用于指定日期/时间模式。LocalDateTimeDateTimeFormatter

String str = "1986-04-08 12:30";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");
LocalDateTime dateTime = LocalDateTime.parse(str, formatter);

设置日期和时间的格式

若要创建一个带格式的字符串，可以使用该方法。LocalDateTimeformat()

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");
LocalDateTime dateTime = LocalDateTime.of(1986, Month.APRIL, 8, 12, 30);
String formattedDateTime = dateTime.format(formatter); // "1986-04-08 12:30"

请注意，在 中预定义为常量的一些常用日期/时间格式。例如：使用从上面格式化实例将产生字符串 。DateTimeFormatterDateTimeFormatter.ISO_DATE_TIMELocalDateTime"1986-04-08T12:30:00"

和 方法可用于所有与日期/时间相关的对象（例如 或parse()format()LocalDateZonedDateTime)

您也可以在不提供图案的情况下使用 或 在 上 使用，如果 是 ISO-8601 格式。LocalDate.parse()LocalDateTime.parse()StringString

例如

String strDate = "2015-08-04";
LocalDate aLD = LocalDate.parse(strDate);
System.out.println("Date: " + aLD);

String strDatewithTime = "2015-08-04T10:11:30";
LocalDateTime aLDT = LocalDateTime.parse(strDatewithTime);
System.out.println("Date with Time: " + aLDT);

输出，

Date: 2015-08-04
Date with Time: 2015-08-04T10:11:30

并且仅在您必须处理其他日期模式时使用。DateTimeFormatter

例如，在下面的示例中，dd MMM uuuu 表示月份中的某一天（两位数字）、月份名称的三个字母（1 月、2 月、3 月,...）和四位数的年份：

DateTimeFormatter dTF = DateTimeFormatter.ofPattern("dd MMM uuuu");
String anotherDate = "04 Aug 2015";
LocalDate lds = LocalDate.parse(anotherDate, dTF);
System.out.println(anotherDate + " parses to " + lds);

输出

04 Aug 2015 parses to 2015-08-04

还要记住，对象是双向的;它可以解析输入和格式化输出。DateTimeFormatter

String strDate = "2015-08-04";
LocalDate aLD = LocalDate.parse(strDate);
DateTimeFormatter dTF = DateTimeFormatter.ofPattern("dd MMM uuuu");
System.out.println(aLD + " formats as " + dTF.format(aLD));

输出

2015-08-04 formats as 04 Aug 2015

（请参阅格式化和分析日期格式化程序的模式的完整列表)

  Symbol  Meaning                     Presentation      Examples
  ------  -------                     ------------      -------
   G       era                         text              AD; Anno Domini; A
   u       year                        year              2004; 04
   y       year-of-era                 year              2004; 04
   D       day-of-year                 number            189
   M/L     month-of-year               number/text       7; 07; Jul; July; J
   d       day-of-month                number            10

   Q/q     quarter-of-year             number/text       3; 03; Q3; 3rd quarter
   Y       week-based-year             year              1996; 96
   w       week-of-week-based-year     number            27
   W       week-of-month               number            4
   E       day-of-week                 text              Tue; Tuesday; T
   e/c     localized day-of-week       number/text       2; 02; Tue; Tuesday; T
   F       week-of-month               number            3

   a       am-pm-of-day                text              PM
   h       clock-hour-of-am-pm (1-12)  number            12
   K       hour-of-am-pm (0-11)        number            0
   k       clock-hour-of-am-pm (1-24)  number            0

   H       hour-of-day (0-23)          number            0
   m       minute-of-hour              number            30
   s       second-of-minute            number            55
   S       fraction-of-second          fraction          978
   A       milli-of-day                number            1234
   n       nano-of-second              number            987654321
   N       nano-of-day                 number            1234000000

   V       time-zone ID                zone-id           America/Los_Angeles; Z; -08:30
   z       time-zone name              zone-name         Pacific Standard Time; PST
   O       localized zone-offset       offset-O          GMT+8; GMT+08:00; UTC-08:00;
   X       zone-offset 'Z' for zero    offset-X          Z; -08; -0830; -08:30; -083015; -08:30:15;
   x       zone-offset                 offset-x          +0000; -08; -0830; -08:30; -083015; -08:30:15;
   Z       zone-offset                 offset-Z          +0000; -0800; -08:00;

   p       pad next                    pad modifier      1

   '       escape for text             delimiter
   ''      single quote                literal           '
   [       optional section start
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   #       reserved for future use
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