Orm

The ability to attach lifecycle events to an entity using simple annotations sometimes is a neat feature in the Java Persistence API. The following short snippets demonstrate how to bind and trigger the different available lifecycle events using an embedded derby database and a bunch of annotations. Dependencies I’m using Hibernate as persistence manager here and Derby as an easy to setup database. In the last step we’ll be writing a test that’s why we’ve added JUnit and Hamcrest. ...

Often we’re writing an application that has to handle entities that – on the one side need to be persisted in a relational database using standards like the Java Persistence API (JPA) and using frameworks like Hibernate ORM or EclipseLink. On the other side those entities and their fields are often stored in a highspeed indexer like Lucene. From this situation arises a bunch of common problems .. to synchronize both data sources, to handle special data mapped in an entity like an office document and so on.. ...

Today we’re going to take a look at the world of object-relational Mapping and how it is done using the Java Persistence API by creating some basic examples, mapping some relations and querying objects using JPQL or the Criteria API.. Prerequisites Java 6 JDK Maven >= 2 If you’d like to take a look behind the scenes e.g. how entities are mapped in your database you could install a RDBMS of your choice .. or just use Derby/JavaDB that is bundled with the JDK 6 ...