6/19/2023 0 Comments Spring jpa annotations![]() ![]() For each EntityManager, operations are maintained by EntityTransaction class. EntityTransaction: It has a one-to-one relationship with the EntityManager class.The set of entity classes represents the data contained within a single data store. In an application, EntityManager instances manage it. Persistence Unit: It defines a set of all entity classes.Entity: The entities are the persistence objects stores as a record in the database.It controls the persistence operations on objects. It creates and manages multiple instances of EntityManager. EntityManagerFactory: It is a factory class of EntityManager.Persistence: It is a class that contains static methods to obtain an EntityManagerFactory instance.The JPA architecture contains the following units: The following figure describes the class-level architecture of JPA that describes the core classes and interfaces of JPA that is defined in the javax persistence package. It shows how to define a POJO as an entity and how to manage entities with relation. JPA is a source to store business entities as relational entities. It is easy to integrate with Spring Framework with the custom namespace.Possibility to integrate custom repository code.The domain base classes provide basic properties.It dynamically generates queries from queries methods name.It means an entity can be partially stored in MySQL and Neo4j (Graph Database Management System). It supports for cross-store persistence.It is a powerful repository and custom object-mapping abstraction.When we need to perform queries JPQL, it allows us to express the queries in terms of Java entities rather than the (native) SQL table and columns.JPA allows us to save and load Java objects and graphs without any DML language at all.JPA allows us to avoid writing DML in the database-specific dialect of SQL.Instead of this, it allows mapping in XML or using Java annotations. ![]()
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