JAXB: how to unmarshall Java object composed from multiple tags or attribute values

Question

I am converting from SAX parser to JAXB - can't figure out how to unmarshall multiple tag/attribute values into single (compassable) Java POJO.

I have xml file like this:

<item validFrom="1950" validUntil="1980">
    <description>some text</description>
</item>

the "validFrom" and "validUntil" values should be composed into a valid "MutableRange" POJO (see definition below).

the Java Item definition that I need to unmarshall it to is:

@XmlRootElement
@XmlAccessorType(XmlAcccessType.FIELD)
public class Item {
    // ??? need help mapping this to be composed from "validFrom", "validUntil" attributes
    private MutableRange validRange;

    @XmlElement
    private String description;
}

// assume all other boilerplate code exists
public class MutableRange {
    private int lowerBound;
    private int upperBound;
}

I have tried using an adapter but its not capturing both: "from" and "until" values together for me to create MutableRange instance. I tried using @XmlMixed with no success.

What is JAXB prescribed way to accomplish this?

Once this is resolved, I will extend MutableRange with ( XmlAdapter ) to serve as a wrapper to create guava's immutable Range object, mapping it to validRange with @XmlJavaTypeAdapter(MutableRange.class)

Answer 1

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.

You can use MOXy's @XmlPath extension to map this use case:

@XmlRootElement
@XmlAccessorType(XmlAcccessType.FIELD)
public class Item {
    @org.eclipse.persistence.oxm.annotations.XmlPath(".")
    private MutableRange validRange;

    @XmlElement
    private String description;
}

For More Information

• http://blog.bdoughan.com/2010/07/xpath-based-mapping.html
• http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html

Answer 2

I would use something as simple as:

public interface MutableRange() {
    public int getLowerBound();
    public int getUpperBound();
    public void setLowerBound(int lowerBound);
    public void setUpperBound(int upperBound);
}

@XmlRootElement(name = "item")
@XmlAccessorType(XmlAccessType.NONE)
public class Item {
    @XmlAttribute(name = "validFrom")
    private int validFrom;
    @XmlAttribute(name = "validUntil")
    private int validUntil;
    @XmlElement(name = "description")
    private String description;

    public MutableRange getValidRange() {
        return new MutableRange() {
            public int getLowerBound() { return validFrom; }
            public int getUpperBound() { return validUntil; }
            public void setLowerBound(int lowerBound) { validFrom = lowerBound; }
            public void setUpperBound(int upperBound) { validUntil = upperBound; }
        }
    }

    public String getDescription() {
       return description;
    }
}