JAX-WS (JAXB) and unmarshalling mixed xs:anyType

Question

I have a web service I have to call using a proxy generated using xcj (for .xsd) and wsimport (for .wsdl) definitions. It is external (i.e. cannot edit it), huge and ever-changing (cannot hand-tweak generated classes).

It has a superclass-like xs:anyType element with mixed="true", similar to sample below.

<Foo type="Bar">
    <id>123</id>
</Foo>

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="Foo">
        <xs:complexType>
            <xs:complexContent mixed="true">
                <xs:extension base="xs:anyType">
                    <xs:attribute name="type" type="xs:string"/>
                </xs:extension>
            </xs:complexContent>
        </xs:complexType>
    </xs:element>

    <xs:element name="Bar">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="id" type="xs:int"/>
                <xs:element name="name" type="xs:string"/>
            </xs:sequence>
        </xs:complexType>
    </xs:element>
</xs:schema>

xjc/wsimport generates Foo as follows

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = { "content" })
@XmlRootElement(name = "Foo")
public class Foo {
    @XmlMixed
    @XmlAnyElement
    protected List<Object> content;
    @XmlAttribute(name = "type")
    protected String type;
    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();

I can marshall a Foo object to its root-less form using Document.getChildNodes() (although I wouldn't mind finding a cleaner way), but I cannot figure out how to unmarshal response's content list (which is ArrayList<ElementNSImpl> after proxy is done with it) to strongly-typed Bar?

public static void main(String[] args) throws Exception {
    Foo foo = new Foo();
    foo.type = "Bar";

    Bar bar = new Bar();
    bar.id = 123;

    JAXBContext context = JAXBContext.newInstance(Foo.class, Bar.class);
    Marshaller marshaller = context.createMarshaller();
    marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

    Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
    marshaller.marshal(bar, document);

    NodeList nodes = document.getFirstChild().getChildNodes();
    foo.content = IntStream.range(0, nodes.getLength()).mapToObj(nodes::item).collect(Collectors.toList());

    StringWriter writer = new StringWriter();
    marshaller.marshal(foo, writer);
    System.out.println(writer);

    Unmarshaller unmarshaller = context.createUnmarshaller();

    // ???
    unmarshaller.unmarshal(foo.content, Bar.class);
}

Answer 1

I think I solved it. Upvotes to whomever comes up a cleaner solution though.

public static List<Object> marshal(Object value) {
    try {
        Class<?> type = value.getClass();
        if (type.isAnonymousClass())
            type = type.getSuperclass();

        Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
        Marshaller marshaller = JAXBContext.newInstance(type).createMarshaller();
        marshaller.marshal(new JAXBElement<>(QName.valueOf("root"), Object.class, value), document);

        NodeList nodes = document.getDocumentElement().getChildNodes();
        return IntStream.range(0, nodes.getLength()).mapToObj(nodes::item).collect(Collectors.toList());
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
}

public static <T> T unmarshal(List<Object> content, Map<QName, String> attributes, Class<T> type) {
    try {
        Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
        document.appendChild(document.createElement("root"));

        if (attributes != null)
            attributes.forEach((q, s) -> document.getDocumentElement().setAttribute(q.getLocalPart(), s));

        if (content != null)
            content.forEach(o -> document.getDocumentElement().appendChild(document.importNode((Node) o, true)));

        Unmarshaller unmarshaller = JAXBContext.newInstance(type).createUnmarshaller();
        return unmarshaller.unmarshal(document, type).getValue();
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
}