JPA Architecture

JPA Architecture: In this section we will discuss the architecture of JPA specification.

JPA Architecture

JPA Architecture

     

JPA Architecture: In this section we will discuss the architecture of JPA specification. Java Persistence API or JPA for short is a lightweight, POJO-based Java framework to persist the Java Objects to the relational database. JPA is uses metadata to map the persistence objects with the database table. JPA supports SQL like query language to ease the process of querying the database. JPA Query language can be used to execute both static and dynamic queries.

JPA supports many ORM frameworks available these days. You can use either free or commercial ORM framework in your JPA based applications. It's also very easy to switch to different ORM frameworks.

List of ORM frameworks:

  1. Hibernate
  2. Toplink from oracle
  3. iBatis
  4. Open JPA

You can easily plug any persistence provider into your JPA application.

JPA Concepts

JPA concept includes the three components Entity, EntityManager and EntityManagerFactory. Following diagram shows the primary components of JPA architecture.

Entity

Entity is the persistence (POJO) objects that represent one record in the table. The Entity is simple annoted POJO class, which is easy to develop. Here are the characteristics of an Entity:

  1. Entity can be persisted to the relational database
  2. Entity is identified by persistence identity (the primary key of the table)
  3. Entity supports transactions
  4. Entity supports inheritance

EntityManager

The EntityManager interface is providing the API for interacting with the Entity. Some of the functions provided by EntityManager API are:

  1. persist ? this method is used to save a new entity
  2. merge ? this method is used to update the sate of entity into database
  3. remove ? this method is used to remove the entity instance

You will learn about all these functions in next sections. We have developed many JPA examples to help you in learning JPA.

EntityManagerFactory

The EntityManagerFactory is used to create an instance of EntityManager. In your application when there is no use of EntityManagerFactory or application shuts down then it is necessary to close the instance of EntityManagerFactory . Once the EntityManagerFactory is closed, all its EntityManagers are also closed.

Tutorials

  1. JPA getResultList Example
  2. JPA Native Queries, JPA Native Queries Tutorials
  3. JPA Sub-Queries
  4. JPA Named Query
  5. JPA One-to-Many Relationship
  6. JPA setParameter (Numbered Parameter)
  7. JPA Many-to-Many Relationship
  8. JPA Max Function
  9. JPA Avg Function
  10. JPA-QL Queries
  11. JPA One-to-One Relationship
  12. JPA Named Parameter
  13. JPA Positional Parameter
  14. JPA Ordering
  15. JPA Grouping
  16. JPA Sum Function
  17. JPA Min Function
  18. JPA Substring() Function
  19. JPA Trim() Function
  20. JPA Lower() Function
  21. JPA Upper Function
  22. JPA Length Function
  23. JPA Locate Function
  24. JPA Mod Function
  25. JDBC vs ORM
  26. JPA Introduction
  27. JPA Architecture
  28. JPA Tutorials
  29. JPA Examples In Eclipse
  30. JPA getSingleResult
  31. JPA update data Example
  32. JPA Features
  33. JPA setFirstResult Example
  34. JPA delete data
  35. JPA executeUpdate
  36. JPA Relationship
  37. JPA Count Function
  38. JPA Examples in NetBeans
  39. JPA Crud
  40. Developing JPA CURD Application with Eclipse