JAXB Collections (List<T>) Use Pascal Case instead of Camel Case for Element Names

Question

I have a number of JAXB beans that are directly marshalled and unmarshalled using Jersey.

E.g.

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "Artifact", propOrder = {
    "artifactId",
    "artifactType",
    "contentHash"
})
@XmlSeeAlso({
    EmailArtifact.class,
    ManagedDocArtifact.class
})
@XmlRootElement(name ="Artifact")
public class Artifact {

    protected String artifactId;
    protected String artifactType;
    protected String contentHash;

...
...
...

}

If I create a GET method that returns a single artifact object. It correctly produces the XML:

<Artifact>
 <artifactId>293289392839283</artifactId>
 <artifactType>EMAIL</artifactType>
 <contentHash>2837873827322</contentHash>
</Artifact>

Here I have been able to successfully control the name of the Artifact element to have a capital "A" at the beginning.

However, I create a GET method that returns collection of artifact objects, I end up with:

<artifacts>
<Artifact>
 <artifactId>293289392839283</artifactId>
 <artifactType>EMAIL</artifactType>
 <contentHash>2837873827322</contentHash>
</Artifact>
<Artifact>
 <artifactId>293289392839283</artifactId>
 <artifactType>EMAIL</artifactType>
 <contentHash>2837873827322</contentHash>
</Artifact>
</artifacts>

As you can see the outer element for the collection has a lower case "A". In order to conform to our own internal standard I would like this to be a capital "A" - Artifacts.

I can not see where this is possible to define within JAXB, is it actually the Jersey framework that is controlling this?

Can we control of the element name generated for collections?

Many thanks,

James

Answer 1

Try using @XmlElementWrapper which supports the name attribute:

@XmlElementWrapper(name="ELEMENTS")
@XmlElement(name="ELEMENT")
protected final List<String> elements = new LinkedList<String>();

Will produce

<ELEMENTS>
  <ELEMENT>one</ELEMENT>
  <ELEMENT>two</ELEMENT>
  ...
</ELEMENTS>

See the JAXB Tutorial for this feature.

Answer 2

OK - I have had an update from the Java Jersey community leader - Paul Sandoz. This is currently an open issue with the Jersey framework and just something that we will have to workaround or accept until it is fixed in a future update.

The workaround as explained in one of the comments above is to introduce a new class for each web service method that returns a collection (e.g. List) of JAXB annotated beans. This class is effectively a class that contains just one member - a List of the JAXB beans. Instead of returning the List in the web service method we return the special class instead. Because we have control over the name of the new class in the XML, e.g. @XmlRootElement(name="Artifacts") we can workaround the problem in the short term.

Hope this helps.

Regards,

James