// create an instance of ObjectModelProvider with the book instance to be marshalled
MappingObjectModelProvider provider = new MappingObjectModelProvider();
provider.mapFieldToElement(Person.class, "dateOfBirth", "", "date-of-birth", SimpleTypeBindings.JAVA_UTIL_DATE);
// marshal the book
marshaller.marshal(dtdReader, provider, person, xmlOutput);
// close DTD reader
dtdReader.close();
final String xml = xmlOutput.getBuffer().toString();