如何使用JAXB将子元素属性绑定到字段？

Question

Given the following XML

<mappings>
  <map>
     <source srcAttr="oof">foo</source>
     <target trgAttr="rab">bar</target>
  </map>
  <map>
    ...

Is it possible with JAXB to unmarshal the <map> elements into a single class Map containing values and attributes of <source> and <target> ?

@XmlRootElement
class Map {

   @XmlElement
   String source;

   @???
   String srcAttr;

   @XmlElement
   String target;

   @???
   String trgAttr;
}

I don't want to create extra classes for Source and target.

Answer 1

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

You could use MOXy's @XmlPath extension to handle this use case:

import javax.xml.bind.annotation.*;
import org.eclipse.persistence.oxm.annotations.XmlPath;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
class Map {

   String source;

   @XmlPath("source/@srcAttr")
   String srcAttr;

   String target;

   @XmlPath("target/@trgAttr")
   String trgAttr;

}

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
• http://blog.bdoughan.com/2012/07/jaxb-no-annotations-required.html

Answer 2

Yes! Just replace ??? with @XmlAttribute annotaion.

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