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Java日期时间 – Java非ISO日历系统
LocalDate使用ISO日历系统，这是公历。
Java Date-Time API还支持其他日历，例如泰国佛教日历，Hijrah日历，Minguo日历和日历。
非ISO日历相关类在java.time.chrono包中定义。
对于每个可用的非ISO日历系统，有一个自定义的年表和自定义的Date类。
自定义的Chronology类表示日历系统，而自定义的Date类表示自定义日历系统中的日期。
每个自定义Chronology类都包含一个INSTANCE常量，表示该类的单例实例。
例子
以下代码显示获取泰国佛教日历中的当前日期：
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);
}
}
上面的代码生成以下结果。
例2
我们可以使用 from()方法将日历系统中的日期转换为另一个日历系统。
以下代码显示如何将ISO日期转换为泰语佛教日期，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);
}
}
上面的代码生成以下结果。
例3
以下代码显示如何将日期转换为不同的日期系统。
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* Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
*
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* from this software without specific prior written permission.
*
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* 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));
}
}
上面的代码生成以下结果。
