Get to Know the Java Persistence Standard Based on Hibernate
Introduction
As a specification, the Jakarta Persistence API (formerly Java Persistence API) is concerned with persistence, which loosely means any mechanism by which Java objects outlive the application process that created them. Not all Java objects need to be persisted, but most applications persist key business objects. The JPA specification lets you define which objects should be persisted, and how they are persisted in your Java applications.
JPA as a Specification
By itself, JPA is not a tool or framework; rather, it defines a set of concepts that guide implementers. While JPA’s object-relational mapping (ORM) model was originally based on Hibernate, it has since evolved. Likewise, while JPA was originally intended for use with relational databases, some JPA implementations have been extended for use with NoSQL datastores. A popular framework that supports JPA with NoSQL is EclipseLink, the reference implementation for JPA 3.
The Core Idea of JPA
The core idea behind JPA, as opposed to JDBC, is that for the most part, JPA lets you avoid the need to “think relationally.” In JPA, you define your persistence rules in the realm of Java code and objects, whereas JDBC requires you to manually translate from code to relational tables and back again.
JPA 3 in Jakarta EE
The Java Persistence API was first released as a subset of the Enterprise JavaBeans 3.0 specification (JSR 220) in Java EE 5. It has since evolved as its own spec, starting with the release of JPA 2.0 in Java EE 6 (JSR 317). JPA was adopted as an independent project of Jakarta EE in 2019. The current release as of this writing is JPA 3.1.
Popular Implementations
Popular JPA implementations like Hibernate and EclipseLink now support JPA 3. Migrating from JPA 2 to JPA 3 involves some namespace changes, but otherwise the changes are under-the-hood performance gains.
Conclusion
JPA provides a standardized and efficient way to manage persistence in Java applications. By abstracting the complexities of database interactions and allowing developers to work with Java objects, JPA enhances productivity and maintains a clean separation between the application’s business logic and data access layer. Whether you are using relational databases or NoSQL datastores, JPA, with implementations like Hibernate and EclipseLink, offers a powerful toolset for data persistence.