You can try Telosys Tools , the Eclipse code generation plugin
works from an existing database with custom speed templates.
See: https://sites.google.com/site/telosystools/
A set of templates is available for GitHub for JPA:
//github.com/telosys-tools-community/jpa-templates-TT206-v2
Java JPA ORMLite,
Java- ORMLite
Spring MVC JPA:
//sites.google.com/site/telosystutorial/springmvc-jpa-springdatajpa
( JPA)