What's the difference between JPA and Hibernate? [closed]

Answer 1

JPA is just a specification which needs concrete implementation. The default implementation oracle provide is "Eclipselink" now. (Toplink is donated by Oracle to Eclipse foundation to merge with eclipselink)

(Reference : http://www.oracle.com/technetwork/middleware/toplink/index-085257.html http://www.eclipse.org/org/press-release/20080317_Eclipselink.php )

Using Eclipselink, one can be sure that the code is portable to any implementation if need arises. Hibernate is also a full JPA implementation + MORE ( Sort of JPA Plus). Hibernate is super set of JPA with some extra Hibernate specific functionality. So app developed in Hibernate may not be compatible when switched to other implementation. Still hibernate is choice of majority of developers as JPA implementation and widely used.

Another JPA implementation is OpenJPA (openjpa.apache.org) which is an extension of Kodo implementation.

Answer 2

I try to explain in very easy words.

Suppose you need a car as we all know their are several A class manufacturer like MERCEDES, BMW , AUDI etc.

Now in above statement CAR(is a specification) as every car have common features like thing with 4 wheels and can be driven on road is car...so its like JPA. And MERCEDES, BMW , AUDI etc are just using common car feature and adding functionality according to their customer base so they are implementing the car specification like hibernate , iBATIS etc.

So by this common features goes to jpa and hibernate is just an implementation according to their jboss need.

1 more thing

JPA includes some basic properties so in future if you want to change hibernate to any other implementation you can easily switch without much headache and for those basic properties includes JPA annotations which can work for any implementation technology, JPQL queries.

So mainly we implement hibernate with JPA type technology just for in case we want to switch our implementation according to client need plus you will write less code as some common features are involved in JPA. If someone still not clear then you can comment as i m new on stack overflow.

Thank you

Answer 3

JPA is a Java API specification which describes the management of relational data in applications using Java Platform. where as Hibernate is a ORM (Object Relational Mapping) library which follows JPA specification.

You can think JPA as a set of Rules which is implemented by Hibernate.

Answer 4

Some things are too hard to understand without a historical perspective of the language and understanding of the JCP.

Often there are third parties that develop packages that perform a function or fill a gap that are not part of the official JDK. For various reasons that function may become part of the Java JDK through the JCP (Java Community Process)

Hibernate (in 2003) provided a way to abstract SQL and allow developers to think more in terms of persisting objects (ORM). You notify hibernate about your Entity objects and it automatically generates the strategy to persist them. Hibernate provided an implementation to do this and the API to drive the implementation either through XML config or annotations.

The fundamental issue now is that your code becomes tightly coupled with a specific vendor(Hibernate) for what a lot of people thought should be more generic. Hence the need for a generic persistence API.

Meanwhile, the JCP with a lot of input from Hibernate and other ORM tool vendors was developing JSR 220 (Java Specification Request) which resulted in JPA 1.0 (2006) and eventually JSR 317 which is JPA 2.0 (2009). These are specifications of a generic Java Persistence API. The API is provided in the JDK as a set of interfaces so that your classes can depend on the javax.persistence and not worry about the particular vendor that is doing the work of persisting your objects. This is only the API and not the implementation. Hibernate now becomes one of the many vendors that implement the JPA 2.0 specification. You can code toward JPA and pick whatever compliant ORM vendor suits your needs.

There are cases where Hibernate may give you features that are not codified in JPA. In this case, you can choose to insert a Hibernate specific annotation directly in your class since JPA does not provide the interface to do that thing.

Source: http://www.reddit.com/r/java/comments/16ovek/understanding_when_to_use_jpa_vs_hibernate/