JAXB-Eclipselink: Inherited properties

问题

I have following use-case for marshalling a POJO to XML using Eclipselink MOXy 2.3:

public abstract class A {

    public abstract getX();

}

public class B extends A {

    private Foo x;

    @Override
    public Foo getX() {
        return this.x;
    }

}

public class C extends B {

    // Various fields and properties here

}

I need to marshal B and C but not A. So i set A to be transient which makes B inherit all its members that will be marshalled when marshalling B. I cant set B to be transient since i need to marshal it by itself, but when i marshal C, i need property B.getX() to be marshalled as well.

Is there any way other than @Override getX() in C to have it marshalled? At the moment it is just one property for which i need to do this, but imagine a large B class with many members, which one would need to @Override in C to marshal them together with C.

Is there any annotation or possibility in the external mapping file to mark a property in a superclass to be inherited by its immediate subclass (or all subclasses)?

What is the Eclipselink/JAXB way to go here?

Regards,

回答1:

There is nothing special you need to do:

I have modified the B class based on one of your previous questions in order to populate the x property:

package forum8739246;

public class B extends A {

    private Foo x;

    public B() {
        x = new Foo();
    }

    public Foo getX() {
        return this.x;
    }

}

oxm.xml

Below is the metadata file that I based on your comments to my original answer.

<?xml version="1.0"?>
<xml-bindings  
    xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    version="2.3"
    package-name="forum8739246">
    <java-types>
        <java-type name="B" xml-accessor-type="FIELD">
            <java-attributes>
                <xml-element java-attribute="x" name="X"/>
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

Demo

package forum8739246;

import java.util.HashMap;
import java.util.Map;

import javax.xml.bind.*;
import javax.xml.namespace.QName;

import org.eclipse.persistence.jaxb.JAXBContextFactory;

public class Demo {

    public static void main(String[] args) throws Exception {
        Map<String, Object> properties = new HashMap<String, Object>(1);
        properties.put(JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY, "forum8739246/oxm.xml");
        JAXBContext jc = JAXBContext.newInstance(new Class[] {C.class},properties);
        System.out.println(jc.getClass());

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        JAXBElement<B> b = new JAXBElement<B>(new QName("b"), B.class, new B());
        marshaller.marshal(b, System.out);

        JAXBElement<C> c = new JAXBElement<C>(new QName("c"), C.class, new C());
        marshaller.marshal(c, System.out);
    }

}

Output

As can be seen from the output the x property is marshalled for both instances of B and C:

class org.eclipse.persistence.jaxb.JAXBContext
<?xml version="1.0" encoding="UTF-8"?>
<b>
   <X/>
</b>
<?xml version="1.0" encoding="UTF-8"?>
<c>
   <X/>
</c>

来源：https://stackoverflow.com/questions/8739246/jaxb-eclipselink-inherited-properties

标签

properties

jaxb

eclipselink

moxy

inherited