JPOX provides transparent persistence of Java objects. It fully complies with the JDO

JPOX (Java Persistent Objects) is an open source and fully compliant implementation of the Java Data Objects (JDO) 1.0 and 2.0 specifications, providing transparent persistence of Java objects. It supports persistence to all of the major relational database management systems on the market today, supporting all of the main object-relational mapping (ORM) patterns, allows querying using either JDOQL or SQL, and comes with its own byte-code enhancer.