Java – use JAXB to ungroup XML into existing objects

I have an XSD generated from a set of existing Java classes. At present, it successfully ungroups XML messages into objects, but what I want to do is that I have an existing object instance so that the unmarshaller only needs to update the fields contained in the message passed to it

For example (forgive any grammatical mistakes, it's just above my head)

If I have an annotated class book with many fields, title, author, published, etc. and the corresponding generated XSD, many fields are set as unnecessary. I want to be able to get the following XML

<Book>
 <title>Dummys guide to JAXB</title>
</Book>

Instead of simply creating a new book instance with only a title set and applying it to an existing instance as an update, you only need to set the title variable on that instance

Solution

JAXB can't do this for you, No However, you can use JAXB to ungroup XML documents into new objects, and then copy the attribute reflection of the new object to the existing object

Commons BeanUtils provides a mechanism for this, such as BeanUtils Copyproperties method But I'm not sure if it's complicated