How to generate JPA mappings with IntelliJ?
Apparently, IntelliJ requires me to describe JPA facet, while JPA facet requires me to create persistence units, which are not actually required by my code.
Is it possible to generate JPA mappings without describing all this glitching stuff?
Related
Hibernate Tools has 2 diffeent configurations regarding this topic.
You got the Console config with the options Hibernate 3.5/3.6/4.0 plus
and Core / (Hibernate) Annotations / JPA Annotations
and later in launch code generator menu we already can select in exporters: Java 5+ and EJB options.
But the behaviour seeems a bit inconsistent for me, as marking JPA annotations without EJB option erases any annotation. So is there any way to make Hibenrate generate non-EJB JPA annotations code (DAO+POJOS)?
THe thing is I don't want to get an injected EntityManager, and I am not using any EJB container but SDK. I am wondering whther there is an smart code generation in that case
I'm starting a new Web project and I've chosen JPA as my persistence ORM engine.
Although I've used OpenJPA in my last project, now I want to use EclipseLink.
Why? It is the JPA reference implementation, it has a lot of documentation and a very good support in the Eclipse IDE. Also, I can't found any benchmark that declares none of them to be the best, so performance is not a factor (all implementations has its own strength points).
But, I want to use the JSR-303 validation spec, and I've chosen hibernate-validator (witch is the reference implementation of the Bean Validation spec).
Moreover, I'm using Spring, and there are a lot of examples with Spring+Hibernate, but I haven't found any opinion that said Spring is better with Hibernate.
Is there any problem mixing this two implementations?
Would be better to use Hibernate JPA with Hibernate Bean validation?
I have been using EclipseLink implementation of JPA with Spring and Hibernate-validation-4.2.0.Final. And no problem so far. Now to answer your question:
Is there any problem mixing this two implementations?
I don't think there will be any problem using EclipseLink JPA implementation with Hibernate implementation for JSR-303 validation spec together, as the purpose of these two specifications are different:
JSR 303 - Bean Validation - defines a metadata model and API for entity validation. This is not tied to a specific application tier or programming model.
JPA - This is the specification of the Java API for the management of persistence and object/relational mapping with Java EE and Java SE.
Spring provides full support for the JSR-303 Bean Validation API. You just need to have a JSR-303 provider, such as Hibernate Validator, present in the classpath and will be detected automatically.
And the Spring JPA, available under the org.springframework.orm.jpa package, offers comprehensive support for the Java Persistence API in a similar manner to the integration with Hibernate.
I'm using hibernate tools under Eclipse Indigo. The Hibernate Console has Annotations option selected and hibernate version is 4.0.
The hibernate tools wizard generates annotations only when I choose Generate EJB3 Annotations option. This introduces a dependency on EJB, and I don't want it.
How do I convince Hibernate tools to generate POJOs (via reverse engineering) that uses plain (non jpa) hibernate annotations?
Then you probably want to specify "Hibernate 3.x" as version, not 4.0. If I remember correctly, Hibernate 4.0 provides JPA-only annotations, plus some few extra ones that would be "extensions".
Now, I think the real question is: why do you want to get rid of JPA? Note that EJB3 != JPA. In fact, JPA is a replacement for what was once known as EJB Entity Beans. And that adding JPA dependency will not add an EJB dependency in your project.
I got an existing table in Oracle database how can I generate my Hibernate Java class etc from this table?
Using Eclipse 3.2, Java 5
Do you mean generate a POJO that maps to the table? You can use the Hibernate Tools plugin for Eclipse. Otherwise you can create the POJO manually and map it to the table using Hibernate Annotations.
The Hibernate Tools for Eclipse and Ant does support reverse engineering. From the website:
Reverse Engineering: The most powerful feature of Hibernate Tools is a database reverse engineering tool that can generate domain model classes and Hibernate mapping files, annotated EJB3 entity beans, HTML documentation or even an entire JBoss Seam application in seconds!
Refer to the provided link for more details.
what is similarity and difference between jpa and hibernate.
JPA (Java Persistence API) is an interface for persistence providers to implement. Hibernate is one such implementation of JPA.
This is the introduction of the JSR-000220 Enterprise JavaBeans 3.0 Final Release (persistence):
This document is the specification of the Java API for the management of persistence and object/rela-
tional mapping with Java EE and Java SE. The technical objective of this work is to provide an
object/relational mapping facility for the Java application developer using a Java domain model to man-
age a relational database.
This persistence API—together with the query language and object/relational mapping metadata defined in this document—is required to be supported under Enterprise JavaBeans 3.0. It is also targeted at being used stand-alone with Java SE.
Leading experts throughout the entire Java community have come together to build this Java persistence standard. This work incorporates contributions from the Hibernate, TopLink, and JDO communities, as well as from the EJB community.
In other words, JPA is the standardized API for persistence. Hibernate provides an implementation of the standard (i.e. it can be used as underlying persistence engine when using JPA).
Prior to JPA, Hibernate was a kind of de facto standard for object persistence in Java. Hibernate is considered as a major contributor to JPA so there are lots of similarities between them (I could even say between all ORM solutions as ORM concepts are common). However, for various reasons, political or technical, the JPA working group couldn't include everything in the first release of JPA so JPA is actually a subset of Hibernate (this is a simplified view but the reality is very close). Hibernate and other JPA implementation provide thus their own proprietary extensions (which means non standards i.e. not portable from one provider to the other) to the JPA standard that you may use, or not.
As pointed out by #Pascal Hibernate existed prior to JPA standard(it is now JSR 317 JPA 2.0, which Hibernate has implemented in 3.5 already out for early use). So there are other providers of JPA e.g. Oracle TopLink, Apache OpenJPA. To use strictly JPA in Hibernate you have to use EntityManager as apposed to the Session which is a Hibernate concept pre-dating JPA. Similarly for strict JPA you have to use EntityManagerFactory as apposed to SessionFactory.
The EntityManager and EntityManagerFactory are, in fact, thin wrappers around the Session and SessionFactory respectively. In addition, core/annotations Hibernate provide extensions to the JPA spec that make your life easier. Before JPA 2 Hibernate had a Criteria API which allowed you to programmatically construct a query in an OO fashion. JPA 2 now makes this functionality standard -- the JPA standard is a bit different from the Hibernate version as it employs generics. So basically the Hibernate functionality is a superset of JPA.
Here's a list of some difference between subjects (excerpts from Hibernate documentation)
Entity. Hibernate goes beyond the JPA specification and provide additional configurations. Some of them are hosted on #org.hibernate.annotations.Entity
dynamicInsert / dynamicUpdate (defaults to false)
selectBeforeUpdate (defaults to false)
polymorphisms
persister
optimisticLock (version, all, dirty, none)
id as a property using a component type
While not supported in JPA, Hibernate lets you place your association directly in the embedded id component (instead of having to use the #MapsId annotation)
Multiple id properties without identifier type
Another, arguably more natural, approach is to place #Id on multiple properties of your entity. This approach is only supported by Hibernate (not JPA compliant) but does not require an extra embeddable component.
Multiple id properties with with a dedicated identifier type
While not JPA standard, Hibernate let's you declare the vanilla associated property in the #IdClass
Identifier generator
Package level definition is not supported by the JPA specification. However, you can use the #GenericGenerator at the package level
Annotations
Hibernate Annotations supports something that is not explicitly supported by the JPA specification. You can annotate a embedded object with the #MappedSuperclass annotation to make the superclass properties persistent (see #MappedSuperclass for more informations).
Discriminator
#org.hibernate.annotations.DiscriminatorOptions allows to optionally specify Hibernate specific discriminator options which are not standardized in JPA. The available options are force and insert
Transaction
Hibernate provides more flush modes than the one described in the JPA specification. In particularFlushMode.MANUAL for long running conversation. Please refer to the Hibernate core reference documentation for more informations.
Static metamodel
Important.
As of today the JPA 2 metamodel does not provide any facility for accessing relational information pertaining to the physical model. It is expected this will be addressed in a future release of the specification.