What is the ObjectFactory role during JAXB-Unmarshalling?

问题

I'm using JAXB 2.2.2 to parse a simple XML-REST stream. This is the piece of code:

JAXBContext jc = JAXBContext.newInstance( "com.example.entities" );
Unmarshaller u = jc.createUnmarshaller();
r = (Response )u.unmarshal( inputStream );

ObjectFactory class:

@XmlRegistry
public class ObjectFactory {

    public Response createRsp() {
        return new Response();
    }
}

Response class:

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name="rsp")
@XmlType
public class Response { ... }

The "com.example.entities" must contain the ObjectFactory class or jaxb.index. I would like to use the ObjectFactory class in order to decide some pojo initialization, but these class is never used: the Response class is always instantiated by class.newInstance() directly. Is there something wrong in this?

回答1:

You can leverage the @XmlType annotation to control how the objects are created:

@XmlType(factoryClass=ObjectFactory.class, factoryMethod="createRsp")
public class Response {
}

For More Information

• http://bdoughan.blogspot.com/2011/06/jaxb-and-factory-methods.html

回答2:

The ObjectFactory class generated by the XJC compiler is not useful to the factoryClass and factoryMethod @XmlType annotation because the factoryMethod must be a static no-arg method and the XJC generate instance methods.

来源：https://stackoverflow.com/questions/5780184/what-is-the-objectfactory-role-during-jaxb-unmarshalling