Marshall object field as attribute - jaxb

Question

Here is what I have so far to marshall my POJO using JAXB :
#XmlRootElement
public class Local {
private Entity entity;
public void setEntity(Entity entity) {
this.entity = entity;
}
#XmlElement
public Entity getEntity() {
return entity;
}
}
and
#XmlRootElement
public class Entity {
private String name;
private String comment;
public void setName(String name){
this.name = name;
}
#XmlAttribute
public String getName(){
return this.name;
}
public void setComment...
#XmlAttribute
public void getComment...
}
With that, I get something like this:
<local>
<entity name="" comment=""></entity>
</local>
However, I would prefer to have the name attribute as an attribute of the local:
<local entityName="" entityComment=""></local>
Is the XmlJavaTypeAdapter a good way to begin with?
Thanks,
Alex

Answer 1

There are a couple of different options to handle this use case:
Option #1 - XmlAdapter (Any JAXB implementation)
You could use an XmlAdapter for this use case. This will work as long as only one attribute value comes from the Entity object:
EntityAdapter
import javax.xml.bind.annotation.adapters.XmlAdapter;
public class EntityAdapter extends XmlAdapter<String, Entity>{
#Override
public String marshal(Entity entity) throws Exception {
if(null == entity) {
return null;
}
return entity.getName();
}
#Override
public Entity unmarshal(String name) throws Exception {
Entity entity = new Entity();
entity.setName(name);
return entity;
}
}
Local
The XmlAdapter is linked with the field/property using the #XmlJavaTypeAdapter annotation:
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
#XmlRootElement
public class Local {
private Entity entity;
public void setEntity(Entity entity) {
this.entity = entity;
}
#XmlAttribute
#XmlJavaTypeAdapter(EntityAdapter.class)
public Entity getEntity() {
return entity;
}
}
For More Information
http://blog.bdoughan.com/2010/07/xmladapter-jaxbs-secret-weapon.html
http://blog.bdoughan.com/2010/12/jaxb-and-immutable-objects.html
Option #2 - #XmlPath (EclipseLink JAXB (MOXy)
Alternatively if you are using EclipseLink JAXB (MOXy), the you could use the #XmlPath extension. This is useful with the Entity object corresponds to multiple XML attributes:
Local
Specifying the XPath "." indicated that the child contents will be written into the parent element
import javax.xml.bind.annotation.*;
import org.eclipse.persistence.oxm.annotations.*;
#XmlRootElement
public class Local {
private Entity entity;
public void setEntity(Entity entity) {
this.entity = entity;
}
#XmlPath(".")
public Entity getEntity() {
return entity;
}
}
Entity
public class Entity {
private String name;
private String comment;
public void setName(String name){
this.name = name;
}
#XmlAttribute(name="entityName")
public String getName(){
return this.name;
}
public void setComment(String comment){
this.comment = comment;
}
#XmlAttribute(name="entityComment")
public String getComment(){
return this.comment;
}
}
For More Information
http://bdoughan.blogspot.com/2010/07/xpath-based-mapping.html
http://blog.bdoughan.com/2010/09/xpath-based-mapping-geocode-example.html
http://blog.bdoughan.com/2011/03/map-to-element-based-on-attribute-value.html
http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html