Java : unable to marshal type "entities.Person" as an element because

Question

In my webservice (using RestEasy) project I have a dependency to a jar. I use from that jar a java class : Person.

My problem is that I need to serialize a Person instance to XML, But I get the following error :

unable to marshal type "entities.Person" as an element because it is missing an @XmlRootElement annotation

However, I cannot change the Person class to add the annotation @XmlRootElement (it is a third party jar).

Is there any other way (methods, libraries, ... ) to marshal a Person instance into XML without annotating Person class?

BTW, here it is the code I use, but it fails because of the missing annotation :

String result;
Person person = personManager.findByPersonId(personId);
StringWriter sw = new StringWriter();
JAXBContext personContext = JAXBContext.newInstance(Person.class);
Marshaller personMarshaller = personContext.createMarshaller();
personMarshaller.marshal(person, sw);
result = sw.toString();
return Response.status(200).entity(result).build();

Thank you a lot.

See: http://stackoverflow.com/questions/12079801/jaxb-unmarshalling-custom-entities-without-annotation — Sotirios Delimanolis, Jan 27 '14 at 15:21
Thank you, the link you gave me is useful, but I wonder if this EclipseLink library is safe to integrate in a commercial product (license)... — user3169231, Jan 27 '14 at 15:34
One of the authors, Blaise, should be around shortly to answer this and that. — Sotirios Delimanolis, Jan 27 '14 at 15:35

score 1 · Accepted Answer · answered Jan 27 '14 at 16:59

JAXB (JSR-222) implementations do not require any annotations be added to your domain model. In the absence of an @XmlRootElement (or @XmlElementDecl) you simply need to wrap your root object in an instance of JAXBElement.

JAXBElement<Person> jaxbElement = new JAXBElement<Person>(new QName("person"), Person.class, person);
personMarshaller.marshal(jaxbElement, sw);

For More Information

http://blog.bdoughan.com/2012/07/jaxb-no-annotations-required.html

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.

If you need to provide metadata for your model, but don't have access to the source then MOXy offers an external metadata document extension you can use for this purpose.