JAXB将XML的一部分解组为类，并将其作为元素或节点保留

Question

Is there a way to unmarshal a XML document partially into Java classes (eg up to a certain depth), and leave the rest as Nodes or Elements (or even XML String or Document), accessible from the unmarshalled part.

Eg I have an XML:

<customer>
  <name>Mike</name>
  <items>
    <item>Car</item>
    <item>Boat</item>
  </items>
</customer>

And Java class:

@XmlRootElement
public class Customer {

    @XmlElement
    private String name;

    // something like this:
    private Node items;
    // or like this:
    // private String items;
}

The reason is because I'm not interested in the items part, I will never parse or access it in Java. But I need to be able to save it and later retrieve it and generate a full XML document. The name element on the other hand I will use in Java code.

I want that the schema of the items part (at least the sub-elements) can be changed without me having to change the Java classes.

Answer 1

You can use @XmlAnyElement(lax=true) to handle this use case. This annotation allows you to unmarshall any XML to a Java object (DOM Node).

@XmlRootElement(name = "customer")
public class Customer {

    @XmlElement
    private String name;
    @XmlAnyElement(lax=true)
    private Object items;    
}

The marshaller will write the XML nodes properly

JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
Customer customer = (Customer) jaxbUnmarshaller.unmarshal(reader);

Marshaller marshaller = jaxbContext.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(customer, System.out);