Convert between LocalDate and XMLGregorianCalendar

Question

在Java 8和XMLGregorianCalendar之间转换LocalDate的最佳方法是什么？

Answer 1

Converting from LocalDate to XMLGregorianCalendar :

LocalDate date = LocalDate.now();
GregorianCalendar gcal = GregorianCalendar.from(date.atStartOfDay(ZoneId.systemDefault()));
XMLGregorianCalendar xcal = DatatypeFactory.newInstance().newXMLGregorianCalendar(gcal);

Converting back is simpler:

xcal.toGregorianCalendar().toZonedDateTime().toLocalDate();

Answer 2

The LocalDate stores only year/month/day information. There is no time nor time-zone information in it. The XMLGregorianCalendar stores date (year/month/day) + optionally time and optionally time zone information.

So converting from LocalDate to XMLGregorianCalendar is simple:

LocalDate in;
XMLGregorianCalendar out;
in = LocalDate.parse("1999-11-11");
out = DatatypeFactory.newInstance().newXMLGregorianCalendar(in.toString());

Converting from XMLGregorianCalendar to LocalDate might be not so simple, because XMLGregorianCalendar may have time and time-zone information which you simply can't store in LocalDate.

However, I guess that if you are converting from XMLGregorianCalendar to LocalDate then the XMLGregorianCalendar is resulting from a nontimezoned xsd:date element (represented as YYYY-MM-DD in the xml). In that case you should convert it like this:

XMLGregorianCalendar in;
LocalDate out;
in = DatatypeFactory.newInstance().newXMLGregorianCalendar("2011-11-11");
out = LocalDate.parse(in.toXMLFormat());

Whole example:

    {
        LocalDate in;
        XMLGregorianCalendar out;
        in = LocalDate.parse("1999-11-11");
        out = DatatypeFactory.newInstance().newXMLGregorianCalendar(in.toString());
        System.out.println("in: " + in.toString());
        System.out.println("out: " + out.toXMLFormat());
    }
    {
        XMLGregorianCalendar in;
        LocalDate out;
        in = DatatypeFactory.newInstance().newXMLGregorianCalendar("2011-11-11");
        out = LocalDate.parse(in.toXMLFormat());
        System.out.println("in: " + in.toXMLFormat());
        System.out.println("out: " + out.toString());
    }

Answer 3

To convert from LocalDate to XMLGregorianCalendar you can use

LocalDate localDate = ...;
GregorianCalendar calender = new GregorianCalendar();
Date utilDate = Date.from( localDate.atStartOfDay( ZoneId.systemDefault() ).toInstant() );
calender.setTime(utilDate);     
XMLGregorianCalendar xmlCal = DatatypeFactory.newInstance().newXMLGregorianCalendar(calender);

And to convert XMLGregorianCalendar back to LocalDate :

XMLGregorianCalendar xmlCal = ...;
Date utilDate = xmlCal.toGregorianCalendar().getTime();
LocalDate localDate = LocalDateTime.ofInstant( utilDate.toInstant(), ZoneId.systemDefault() ).toLocalDate();

Answer 4

The following is a simple way to convert from LocalDate to XMLGregorianCalendar which both preserves the undefined fields (hours, timezone, etc.) and is efficient (ie no conversion to/from String). Unlike some of the other solutions this results in XML dates without timezones, eg <date>2018-11-06</date> instead of <date>2018-11-06+01:00</date> .

LocalDate date = ...;
XMLGregorianCalendar xmlCal = DatatypeFactory.newInstance().newXMLGregorianCalendar();
xmlCal.setYear(date.getYear());
xmlCal.setMonth(date.getMonthValue());
xmlCal.setDay(date.getDayOfMonth());

Converting back is a bit simpler:

XMLGregorianCalendar xmlCal = ...
LocalDate date = LocalDate.of(xmlCal.getYear(), xmlCal.getMonth(), xmlCal.getDay());