Middlegen

Middlegen is a free general-purpose database-driven code generation engine based on JDBC , Velocity , Ant and XDoclet . If you already have a database, you can use Middlegen to generate...

Persistance layer with EJB (CMP 2.0)
Persistance layer with JDO
Persistance layer with Hibernate
Persistance layer with Torque
Database GUI with JSP/Struts

Developping database-driven applications with Middlegen is easy:

Create the database with your preferred database modeler tool
Configure Middlegen to access the database and read the database schema
Run Middlegen from Ant, and (optional) with the GUI tool, rename tables and columns, tune relationships and type-mappings
Generate your source code with Middlegen
Run XDoclet to generate the additional files like EJB homes and interfaces, and deployment descriptors
Compile and deploy your application