Question

I’m just changing design errors made in the past, but want to keep backwards compatibility of my software. For this I would need some way to map two flavors of an xml file into one java bean. Can this be done using two JAXB annotations on one attribute/element? I understand the marshalling would be ambiguous, but the unmarshalling could work. Is there some nice way of doing this?

p.s.: I don’t care about marshalling.

Answer 1

You can map twice:

• the first time using annotations
• the second time using XML resources.

Or just two XML mappings instead of annotations.

For XML resource mappings, there’s a number of options:

• Annox: http://confluence.highsource.org/display/ANX/JAXB+User+Guide (I wrote it so it comes first :))
• EclipseLink Moxy: http://eclipse.org/eclipselink/moxy.php
• JAXB Intoductions: http://community.jboss.org/wiki/JAXBIntroductions

With Annox you can easily map twice using XML mapping resources with different extensions like MyClass.ann1.xml or MyClass.ann2.xml. (It’s MyClass.ann.xml per default, but the adjustment is trivial.)

Here’s a sample of what mappings look like:

<class xmlns="http://annox.dev.java.net" xmlns:annox="http://annox.dev.java.net" xmlns:jaxb="http://annox.dev.java.net/javax.xml.bind.annotation">

    <jaxb:XmlAccessorType value="FIELD"/>
    <jaxb:XmlType name="" propOrder="productName quantity usPrice comment shipDate"/>
    <field name="productName">
        <jaxb:XmlElement required="true"/>
    </field>
    <field name="usPrice">
        <jaxb:XmlElement name="USPrice" required="true"/>
    </field>
    <field name="shipDate">
        <jaxb:XmlSchemaType name="date"/>
    </field>
    <field name="partNum">
        <jaxb:XmlAttribute required="true"/>
    </field>
</class>