XML Stack Overflow

I have some very simple XML that I wish to unmarshall. I'm only interested in the values for one of the elements which repeats. Here's some sample XML:

<Document>
  <HeaderGuff>Whatever</HeaderGuff>
  <Foos>
    <FooId>1</FooId>
    <FooId>2</FooId>
  </Foos>
</Document>

I would like to use JAXB to allow me to iterate of the FooId's as a Long.

The usual examples require creating a data class with setFooId and getFooId methods. Is there a way to unmarshall directly to Long such that I can do this:

for ( Long fooId : <something JAXB> )

I do not want to load all the identifiers into memory at once as there are potentially many of them, and they are only needed one at a time for individual processing.