persistence4j is a small and lightweight Java object persister that uses JDBC to persist data into a relational database. The library frees you from writing the Data transfer objects - just create a POJO and simply save it. Transactional and non-transactional connections are supported and can be configured from the simple properties file.
SpiderDB is a lightweight database schema crawler library developed using Java. It is a simple library that can be used to Crawler the underlying schema of a database and return POJO objects, which makes it very easy to use. This library takes care of all the differences among the various database management systems, and makes application code free from the DBMS differences.You keep using same POJOs even if you change the underlying DBMS.