Java 非ISO日歷系統(tǒng)

Java日期時(shí)間 - Java非ISO日歷系統(tǒng)

LocalDate使用ISO日歷系統(tǒng)，這是公歷。

Java Date-Time API還支持其他日歷，例如泰國(guó)佛教日歷，Hijrah日歷，Minguo日歷和日歷。

非ISO日歷相關(guān)類在java.time.chrono包中定義。

對(duì)于每個(gè)可用的非ISO日歷系統(tǒng)，有一個(gè)自定義的年表和自定義的Date類。

自定義的Chronology類表示日歷系統(tǒng)，而自定義的Date類表示自定義日歷系統(tǒng)中的日期。

每個(gè)自定義Chronology類都包含一個(gè)INSTANCE常量，表示該類的單例實(shí)例。

例子

以下代碼顯示獲取泰國(guó)佛教日歷中的當(dāng)前日期：

import java.time.chrono.ThaiBuddhistChronology;
import java.time.chrono.ThaiBuddhistDate;

public class Main {

  public static void main(String[] args) {
    ThaiBuddhistChronology thaiBuddhistChrono = ThaiBuddhistChronology.INSTANCE;
    ThaiBuddhistDate now = thaiBuddhistChrono.dateNow();
    ThaiBuddhistDate now2 = ThaiBuddhistDate.now();
    System.out.println("Current Date  in Thai  Buddhist: " + now);
    System.out.println("Current Date  in Thai  Buddhist: " + now2);
  }
}

上面的代碼生成以下結(jié)果。

例2

我們可以使用 from()方法將日歷系統(tǒng)中的日期轉(zhuǎn)換為另一個(gè)日歷系統(tǒng)。

以下代碼顯示如何將ISO日期轉(zhuǎn)換為泰語(yǔ)佛教日期，反之亦然。

import java.time.LocalDate;
import java.time.chrono.ThaiBuddhistDate;

public class Main {

  public static void main(String[] args) {
    ThaiBuddhistDate thaiBuddhistNow = ThaiBuddhistDate.now();
    LocalDate isoNow = LocalDate.now();
    System.out.println("Thai  Buddhist Current Date: " + thaiBuddhistNow);
    System.out.println("ISO  Current Date: " + isoNow);

    // Convert Thai Buddhist date to ISO date and vice versa
    ThaiBuddhistDate thaiBuddhistNow2 = ThaiBuddhistDate.from(isoNow);
    LocalDate isoNow2 = LocalDate.from(thaiBuddhistNow);
    System.out.println("Thai  Buddhist Current Date  from  ISO:  "
        + thaiBuddhistNow2);
    System.out.println("ISO  Current Date  from  Thai  Buddhist: " + isoNow2);

  }
}

上面的代碼生成以下結(jié)果。

例3

以下代碼顯示如何將日期轉(zhuǎn)換為不同的日期系統(tǒng)。

/*
 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
import java.time.*;
import java.time.chrono.*;
import java.time.format.*;
import java.time.temporal.*;
import java.util.Locale;
import java.io.PrintStream;

/*
 * Convert LocalDate -> ChronoLocalDate -> String and back.
 */

public class Main {

  /**
   * Converts a LocalDate (ISO) value to a ChronoLocalDate date using the
   * provided Chronology, and then formats the ChronoLocalDate to a String using
   * a DateTimeFormatter with a SHORT pattern based on the Chronology and the
   * current Locale.
   *
   * @param localDate
   *          - the ISO date to convert and format.
   * @param chrono
   *          - an optional Chronology. If null, then IsoChronology is used.
   */
  public static String toString(LocalDate localDate, Chronology chrono) {
    if (localDate != null) {
      Locale locale = Locale.getDefault(Locale.Category.FORMAT);
      ChronoLocalDate cDate;
      if (chrono == null) {
        chrono = IsoChronology.INSTANCE;
      }
      try {
        cDate = chrono.date(localDate);
      } catch (DateTimeException ex) {
        System.err.println(ex);
        chrono = IsoChronology.INSTANCE;
        cDate = localDate;
      }
      String pattern = "M/d/yyyy GGGGG";
      DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern(pattern);
      return dateFormatter.format(cDate);
    } else {
      return "";
    }
  }

  /**
   * Parses a String to a ChronoLocalDate using a DateTimeFormatter with a short
   * pattern based on the current Locale and the provided Chronology, then
   * converts this to a LocalDate (ISO) value.
   *
   * @param text
   *          - the input date text in the SHORT format expected for the
   *          Chronology and the current Locale.
   *
   * @param chrono
   *          - an optional Chronology. If null, then IsoChronology is used.
   */
  public static LocalDate fromString(String text, Chronology chrono) {
    if (text != null && !text.isEmpty()) {
      Locale locale = Locale.getDefault(Locale.Category.FORMAT);
      if (chrono == null) {
        chrono = IsoChronology.INSTANCE;
      }
      String pattern = "M/d/yyyy GGGGG";
      DateTimeFormatter df = new DateTimeFormatterBuilder().parseLenient()
          .appendPattern(pattern).toFormatter().withChronology(chrono)
          .withDecimalStyle(DecimalStyle.of(locale));
      TemporalAccessor temporal = df.parse(text);
      ChronoLocalDate cDate = chrono.date(temporal);
      return LocalDate.from(cDate);
    }
    return null;
  }

  public static void main(String[] args) {
    LocalDate date = LocalDate.of(1996, Month.OCTOBER, 29);
    System.out.printf("%s%n", toString(date, JapaneseChronology.INSTANCE));
    System.out.printf("%s%n", toString(date, MinguoChronology.INSTANCE));
    System.out.printf("%s%n", toString(date, ThaiBuddhistChronology.INSTANCE));
    System.out.printf("%s%n", toString(date, HijrahChronology.INSTANCE));

    System.out.printf("%s%n",
        fromString("10/29/0008 H", JapaneseChronology.INSTANCE));
    System.out.printf("%s%n",
        fromString("10/29/0085 1", MinguoChronology.INSTANCE));
    System.out.printf("%s%n",
        fromString("10/29/2539 B.E.", ThaiBuddhistChronology.INSTANCE));
    System.out.printf("%s%n",
        fromString("6/16/1417 1", HijrahChronology.INSTANCE));
  }
}

上面的代碼生成以下結(jié)果。