<p>I wonder if with a simple <code>Map&lt;String,Object&gt;</code> implementation for plain records is enough.</p>

<p>I want to do it similar to Ror. When you add a field to the table in the database automatically you have access to the field in the Dto.</p>

<p>I don't want to add a field and then have to add the same field to the DTO declaration. It isn't DRY.</p>

What I think you're looking for a is very lightweight Object Relational Mapping tool?
If you want to roll your own, then there is a tiny example one as part of
this article
on developerWorks.
You may want to look at any number of others but Hibernate, JPA and JDO are probably the most popular.
Prevayler
type systems may be what you're looking for. Of course, none of this may not be what you're after. Could you be a little more specific?