JAXB: How do I annotate classes so that they belong to different namespaces?

Question

I want to have JAXB-annotated classes which would be marshalled/unmarshalled to different XML namespaces.

What I need is something like:

<someRootElement xmlns="urn:my:ns1"
    xmlns:a="urn:my:ns2" xmlns:b="urn:my:ns3">

  <someElement/>
  <a:someElement/>
  <b:someElement/>

</someRootElement>

How can it be done?

Can it be done programatically? (without the need for JAXB's .xjb bindings file?)

Answer 1

@XmlRootElement(name="someRootElement", namespace = "urn:my:ns1")
class Test {
    @XmlElement(name="someElement", namespace="urn:my:ns1")
    String elem1 = "One";

    @XmlElement(name="someElement", namespace="urn:my:ns2")
    String elem2 = "Two";

    @XmlElement(name="someElement", namespace="urn:my:ns3")
    String elem3 = "Three";
}

This marshals into the following XML:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<someRootElement xmlns="urn:my:ns1" xmlns:ns2="urn:my:ns2" xmlns:ns3="urn:my:ns3">
    <someElement>One</someElement>
    <ns2:someElement>Two</ns2:someElement>
    <ns3:someElement>Three</ns3:someElement>
</someRootElement>

If you are using JAXB RI and don't like the default ns2 and ns3 namespace prefixes, you need to provide your own NamespacePrefixMapper.