How do you specify the date format used when JAXB marshals xsd:dateTime?

When JAXB marshals a date object (XMLGregorianCalendar) into an xsd:dateTime element. How can you specify the format of the resulting XML?

For example: The default data format uses milliseconds <StartDate>2012-08-21T13:21:58.000Z</StartDate> I need to omit the milliseconds. <StartDate>2012-08-21T13:21:58Z</StartDate>

How can I specify the output form/date format that I want it to use? I'm using javax.xml.datatype.DatatypeFactory to create the XMLGregorianCalendar object.

XMLGregorianCalendar xmlCal = datatypeFactory.newXMLGregorianCalendar(cal);

You can use an XmlAdapter to customize how a date type is written to XML.

package com.example;

import java.text.SimpleDateFormat;
import java.util.Date;

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class DateAdapter extends XmlAdapter<String, Date> {

    private final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    @Override
    public String marshal(Date v) throws Exception {
        synchronized (dateFormat) {
            return dateFormat.format(v);
        }
    }

    @Override
    public Date unmarshal(String v) throws Exception {
        synchronized (dateFormat) {
            return dateFormat.parse(v);
        }
    }

}

Then you use the @XmlJavaTypeAdapter annotation to specify that the XmlAdapter should be used for a specific field/property.

@XmlElement(name = "timestamp", required = true) 
@XmlJavaTypeAdapter(DateAdapter.class)
protected Date timestamp; 

Using a xjb binding file:

<xjc:javaType name="java.util.Date" xmlType="xs:dateTime"
        adapter="com.example.DateAdapter"/>

will produce the above mentioned annotation.
(By eventually adding the xjc namespace: xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc")

I use a SimpleDateFormat to create the XMLGregorianCalendar, such as in this example:

public static XMLGregorianCalendar getXmlDate(Date date) throws DatatypeConfigurationException {
	return DatatypeFactory.newInstance().newXMLGregorianCalendar(new SimpleDateFormat("yyyy-MM-dd").format(date));
}

public static XMLGregorianCalendar getXmlDateTime(Date date) throws DatatypeConfigurationException {
	return DatatypeFactory.newInstance().newXMLGregorianCalendar(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss").format(date));
}

The first method creates an instance of XMLGregorianCalendar that is formatted by the XML marshaller as a valid xsd:date, the second method results in a valid xsd:dateTime.

Very easy way to me. Formatting XMLGregorianCalendar for marshalling in java.

I just create my data in the good format. The toString will be called producing the good result.

public static final XMLGregorianCalendar getDate(Date d) {
	try {
		return DatatypeFactory.newInstance().newXMLGregorianCalendar(new SimpleDateFormat("yyyy-MM-dd").format(d));
	} catch (DatatypeConfigurationException e) {
		return null;
	}
}

https://www.baeldung.com/jaxb

public class DateAdapter extends XmlAdapter<String, Date> {
 
    private static final ThreadLocal<DateFormat> dateFormat 
      = new ThreadLocal<DateFormat>() {
 
        @Override
        protected DateFormat initialValue() {
            return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        }
    }
 
    @Override
    public Date unmarshal(String v) throws Exception {
        return dateFormat.get().parse(v);
    }
 
    @Override
    public String marshal(Date v) throws Exception {
        return dateFormat.get().format(v);
    }
}

Usage:

import com.company.LocalDateAdapter.yyyyMMdd;

//...

@XmlElement(name = "PROC-DATE")
@XmlJavaTypeAdapter(yyyyMMdd.class)
private LocalDate processingDate;

LocalDateAdapter

import javax.xml.bind.annotation.adapters.XmlAdapter;
import org.joda.time.LocalDate;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

public class LocalDateAdapter extends XmlAdapter<String, LocalDate> {

  public static final class yyyyMMdd extends LocalDateAdapter {
    public yyyyMMdd() {
      super("yyyyMMdd");
    }
  }

  public static final class yyyy_MM_dd extends LocalDateAdapter {
    public yyyy_MM_dd() {
      super("yyyy-MM-dd");
    }
  }

  private final DateTimeFormatter formatter;

  public LocalDateAdapter(String pattern) {
    formatter = DateTimeFormat.forPattern(pattern);
  }

  @Override
  public String marshal(LocalDate date) throws Exception {
    return formatter.print(date);
  }

  @Override
  public LocalDate unmarshal(String date) throws Exception {
    return formatter.parseLocalDate(date);
  }
}