Caster - XML/JAVA Object Mapping

Castor is an Open Source data binding framework for Java[tm].Castor provides Java-to-XML binding

Castor XML can marshal almost any "bean-like" Java Object to and from XML. In most cases the marshalling
framework uses a set of ClassDescriptors and FieldDescriptors to describe how an Object should be marshalled
and unmarshalled from XML.

The mapping rules can be mentioned in xml files which makes it easy for customization.

It also has features for java code generation from xml.

http://www.castor.org/