Spring DaoSupport and @PersistanceContext EntityManager?


Spring DaoSupport and @PersistanceContext EntityManager?



One of the most difficult things about understand Spring is that Spring supports multiple approaches to the same problem.

So in my application I using injected EntityManager using the @PersistanceContext annotation, for example:

@Repository public class JpaDao extends JpaDaoSupport implements Dao {      @PersistenceContext(unitName = "PersistanceUnit", type = PersistenceContextType.EXTENDED)     private EntityManager em; 

Is this approach compatible with extending JpaDaoSupport (which requires injecting in an EntityManager)? To me it looks like two incompatible approaches to the solving the same problem, but I would like some advice from someone who has more experience with Spring.

If I shouldn't be extending JpaDaoSupport, how should I build my DAO using the @PersistenceContext approach?




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1:



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You're correct that they are two different approaches to the same problem.


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Which one is "better" is a matter of taste, I think.


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Using annotations has the benefit of avoiding Spring import dependencies in your code, and even the Spring JavaDoc for JpaDaoSupport suggests using them for new JPA projects.


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JpaDaoSupport is there to make Spring's support for JPA equivalent to its support for other ORM strategies (HibernateDaoSupport, JdbcDaoSupport, TopLinkDaoSupport, etc.).


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In those cases, annotation-based injection isn't an option..
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2:


For injecting the EntityManager you just need to add the next definition.
<bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" /> 
you can get more information about this topic in this post from the oficial blog.


3:


I would rather recommend you not to extend JpaDaoSupport, spring will do everything for you.

Follow the link suggested by diega for more information, same blog I have followed to upgrade my application to support spring - jpa.

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