What is JPA

What is JPA

JPA can be seen as part of the EJB3.0, but it is not limited to EJB 3.0, which you can use in Web applications, even desktop applications. JPA is only a Java persistence standard, it is intended to standardize the ORM (Object Relational Mapping model) framework, the ORM framework has a unified interface, a unified approach, it does not have specific implementation code, because the JPA framework supports large data sets, transactions, concurrency and other container-level transactions, which makes the JPA Beyond the limitations of the simple persistence framework, it plays a greater role in enterprise applications.

Sun introduces the new JPA ORM specification for two reasons: one that simplifies the development of existing Java EE and Java SE applications, and second, Sun wants to integrate ORM technology to achieve the world, which means switching between different ORM frameworks can be achieved.

The overall idea of JPA is broadly consistent with existing ORM frameworks such as Hibernate, TopLink, JDO, and so on. In general, JPA includes the following 3 areas of technology:

ORM Mapping Meta Data

JPA supports both XML and JDK5.0 annotations in the form of metadata that describes the mapping between objects and tables, in which the framework persists entity objects into database tables;

Api

Used to manipulate entity objects, perform CRUD operations, the framework replaces everything we do in the background, and developers are freed from tedious JDBC and SQL code.

Query Language (JPQL: is an object-oriented SQL language)

This is an important aspect of persistent operations, querying data through object-oriented rather than database-oriented query language to avoid tightly coupling the SQL statements of the program.

What is JPA