如何在JAXB中向元素添加属性

Question

I am new to JAXB library and not able to get the solution for adding @XmlAttribute to the existing Code.

I have an XML which have two element (Name and Value) as show below :

<ns4:Envelope xmlns:ns2="xyz/123" xmlns:ns3="http://schemas.xmlsoap.org/soap/encoding/" xmlns:ns4="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns6="http://www.w3.org/2001/XMLSchema-instance" xmlns:ns5="http://www.w3.org/2001/XMLSchema" xmlns:abc="abc">
    <ns4:Header>
        <ns2:ID ns4:mustUnderstand="1">testId</ns2:ID>
    </ns4:Header>
    <ns4:Body>
        <ns2:Set>
            <List ns3:arrayType="abc:hash[1]">
                <Struct>
                    <Name>Interval</Name>
                    <Value xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:int">10</Value>
                </Struct>
            </List>
        </ns2:Set>
    </ns4:Body>
</ns4:Envelope>

In the above XML, the xsi:type is been getting generated Automatically by JAXB. The Struct Class having the below Code

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "Struct", propOrder = {
    "name",
    "value"
})
public class Struct {

    @XmlElement(name = "Name", required = true)
    protected String name;
    @XmlElement(name = "Value", required = true)
    protected Object value;

    public String getName() {
        return name;
    }
    public void setName(String value) {
        this.name = value;
    }

    public Object getValue() {
        return value;
    }

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

As you can see the type is not been set in the above class. I want to have some provision to add type as per user defined, rather than getting generated as per the data type.

I am not sure how can I add Attribute to this Struct Class, which can add the type to "Value" Element (As we can see the Value Element is Simple String Object)

Answer 1

If you just want a type attribute, try something like this:

public class TypedValue {

    @XmlAttribute
    protected String type;
    @XmlValue
    protected String value;
}

instead of Object in Struct.value .

The xsi:type is a very special thing for inheritance.

Answer 2

If you want to customize how JAXB represents something you can always create an XmlAdapter for it.

Adaping a Field/Property

The @XmlJavaTypeAdatper annotation is used to reference the XmlAdapter .

@XmlElement(name = "Value", required = true)
@XmlJavaTypeAdapter(ValueAdapter.class)
protected Object value;

XmlAdapter

Is responsible for converting between the real object in your domain model, and the one you want to marshal to get the desired XML.

public class ValueAdapter extends XmlAdapter<MyAdaptedObject, Object> {
    ...
}

MyAdaptedObject

Is a POJO that will marshal to your desired XML.