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

Answer 1

JPA or Java Persistence API is a standard specification for ORM implementations whereas Hibernate is the actual ORM implementation or framework.

Answer 2

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

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. Hibernate is super set of JPA with some extra Hibernate specific functionality. So application 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, which is an extension of Kodo implementation.

JPA vs Hibernate

Answer 3

From the Wiki.

Motivation for creating the Java Persistence API

Many enterprise Java developers use lightweight persistent objects provided by open-source frameworks or Data Access Objects instead of entity beans: entity beans and enterprise beans had a reputation of being too heavyweight and complicated, and one could only use them in Java EE application servers. Many of the features of the third-party persistence frameworks were incorporated into the Java Persistence API, and as of 2006 projects like Hibernate (version 3.2) and Open-Source Version TopLink Essentials have become implementations of the Java Persistence API.

As told in the JCP page the Eclipse link is the Reference Implementation for JPA. Have look at this answer for bit more on this.

JPA itself has features that will make up for a standard ORM framework. Since JPA is a part of Java EE spec, you can use JPA alone in a project and it should work with any Java EE compatible Servers. Yes, these servers will have the implementations for the JPA spec.

Hibernate is the most popular ORM framework, once the JPA got introduced hibernate conforms to the JPA specifications. Apart from the basic set of specification that it should follow hibernate provides whole lot of additional stuff.

Answer 4

As you state JPA is just a specification, meaning there is no implementation. You can annotate your classes as much as you would like with JPA annotations, however without an implementation nothing will happen. Think of JPA as the guidelines that must be followed or an interface, while Hibernate's JPA implementation is code that meets the API as defined by the JPA specification and provides the under the hood functionality.

When you use Hibernate with JPA you are actually using the Hibernate JPA implementation. The benefit of this is that you can swap out Hibernate's implementation of JPA for another implementation of the JPA specification. When you use straight Hibernate you are locking into the implementation because other ORMs may use different methods/configurations and annotations, therefore you cannot just switch over to another ORM.

For a more detailed description read my blog entry.

Answer 5

JPA is the interface while Hibernate is the implementation.

Traditionally there have been multiple Java ORM solutions:

• Hibernate
• TopLink
• JDO

each implementation defining its own mapping definition or client API. The JPA expert group gathered the best of all these tools and so they created the Java Persistence API standard.

A standard persistence API is very convenient from a client point of view, making it relatively easy to switch one implementation with the other (although in practice it's not that simple because on large projects you'll have to use specific non-standard features anyway).

The standard JPA has pushed Java ORM competition to a new level and this can only lead to better implementations.

As explained in my book, High-Performance Java Persistence, Hibernate offers features that are not yet supported by JPA:

• extended identifier generators (hi/lo, pooled, pooled-lo)
• transparent prepared statement batching
• customizable CRUD (@SQLInsert, @SQLUpdate, @SQLDelete) statements
• static or dynamic collection filters (e.g. @FilterDef, @Filter, @Where) and entity filters (e.g. @Where)
• mapping properties to SQL fragments (e.g. @Formula)
• immutable entities (e.g. @Immutable)
• more flush modes (e.g. FlushMode.MANUAL, FlushMode.ALWAYS)
• querying the second-level cache by the natural key of a given entity
• entity-level cache concurrency strategies (e.g. Cache(usage = CacheConcurrencyStrategy.READ_WRITE))
• versioned bulk updates through HQL
• exclude fields from optimistic locking check (e.g. @OptimisticLock(excluded = true))
• versionless optimistic locking (e.g. OptimisticLockType.ALL, OptimisticLockType.DIRTY)
• support for skipping (without waiting) pessimistic lock requests
• support for Java 8 Date and Time
• support for multitenancy
• support for soft delete (e.g. @Where, @Filter)

These extra features allow Hibernate to address many persistence requirements demanded by large enterprise applications.

Answer 6

While JPA is the specification, Hibernate is the implementation provider that follows the rules dictated in the specification.