Dave
I don't know if its quite what you are looking for, but have you seen
the Jakarta Torque Project
(http://jakarta.apache.org/turbine/torque/index.html)? It is built on
the Village API which is itself (roughly) an abstraction of JDBC.
I have been using it mostly as part of the overall Turbine framework,
which can be found on the same site and although there are some teething
problems with postgres, it seems promising.
hth
colm