JAXB逐元素解组列表

Question

I need some help with unmarshalling some XML. Especially with unmarshalling a list of elements. See the following example:

@XmlRootElement(name="element")
public class Element
{
    private ArrayList<Element> children;

    public ArrayList<Element> getChildren() {
        return children;
    }

    @XmlElementWrapper(name = "children")
    @XmlElement(name = "element")
    public void setChildren(ArrayList<Element> children) {
        this.children = children;
    }
}

This will unmarshal the list perfectly, BUT what I need is an unmarshalling of all children element by element and adding them through some "addElement" method:

    public void addElement(Element element) {
        children.add(element)
    }

Is this possible with some simple annotation magic ? Of course I could loop through the elements and call "addElement".

Answer 1

You can simply pretend your appender is a setter.

Example :

@XmlRootElement(name = "element")
public class Element {
    private List<Element> children = new LinkedList<Element>();

    @XmlTransient
    public List<Element> getChildren() {
        return children;
    }

    @XmlElement(name = "element")
    public void setChild(Element child) {
        this.children.add(child);
    }

    private String value;

    @XmlAttribute
    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }
}

JAXB will invoke the setter every time the element element is encountered. This adds the unmarshalled element to the list. The list getter is @XmlTransient to avoid handling by JAXB.

Update

I've forgotten to add that this won't work with the @XmlWrapperElement as it expects a collection property.