BeanKeeper is a full featured, powerful object/relational persistence and query library. It has a unique philosophy of simpleness and ease of use: it does not require config files, annotations, code generation, code "enhancing", or any kind of tools to be used. It handles simple Java beans (or POJOs) and its query service returns lists. Despite its simpleness, under the hood the library takes care of all the necessary logic: transaction visibility, result list paging, keys and ids, table creation/modification, class relations, inheritance/polymorphism, case sensitiveness, and much more. It currently supports: Oracle, HSQLDB, MySQL, and PostgreSQL.
