In most cases code generators take the database schema (con.getMetaData()) and create corresponding java classes, for example one data class and one manager class per table.

Some OR tools (TopLink, Cocobase, etc) create both java classes and database schema from single xml master file.

Chris Smith says that iBATIS involves a lot more SQL work than Hibernate and leaves you to solve more of your own problems, but it requires a lot less conceptual understanding. iBATIS basically seems to be about mapping a ResultSet to an object, and nothing else. Hibernate is more concerned with the hard problems: caching and connection pooling; representing relationships between entities in a very flexible and customizable way, etc. As a result, iBATIS appears to be mostly about avoiding the effort of writing repetitive glue code from JDBC, while Hibernate is about abstracting away from JDBC and treating data according to the object model instead.