Hibernate vs JPA in Java

What is Hibernate?

Hibernate, an open-source ORM tool, simplifies Object-Relational persistence in Java applications. It's a widely adopted Java Persistence API (JPA) implementation that connects Java objects with databases using XML files to minimize routine programming tasks. Hibernate includes an internal cache mechanism for improved performance and uses HQL (Hibernate Query Language) to generate database queries, eliminating the need for crafting database-specific queries. With Hibernate, table creation and data retrieval from multiple tables are streamlined.

Following are the databases that hibernate supports:

• PostgreSQL
• MySQL
• Oracle
• Microsoft SQL Server Database
• HSQL Database Engine
• Sybase SQL Server
• DB2/NT
• FrontBase
• Informix Dynamic Server

Key Features of Hibernate

Following are the features of the Hibernate framework:

1. Open-source:

   Hibernate is an open-source software, which means the source code is available for developers to use and integrate into their Java applications without any cost.

2. Auto table generation:

   Automatically generates the table for the database, which means programmers need not worry about the query implementation.

3. Relationship:

   Hibernate framework supports One-To-One, One-To-One, One-To-Many, Many-To-Many relationships.

4. Support Association:

   Hibernate supports composition and aggregation association type of relationship.

5. Support Inheritance:

   Hibernate follows the concept of inheritance, i.e., if you save a derived class object, its base class object will also be stored in the database.

6. Lazy Loading:

   Hibernate has a lazy loading feature; using this concept, it retrieves only the necessary object required for execution, resulting in improved performance of the application.

7. Pagination Support:

   Getting pagination in hibernate is quite simple.

In Hibernate, you don't need to use a try-catch-exception block as you would in JDBC. This is because Hibernate deals with different kinds of exceptions called "Unchecked" or "run-time" exceptions. These exceptions are automatically managed, so you don't have to explicitly catch them or specify a "throws" clause.

What is JPA?

Speaking of JPA vs. Hibernate, for almost every application, you need to perform database operations like storing and retrieval for handling a large amount of data. This is a time-consuming task so thus the need for JPA arose.

Java Persistence API stands as a Java specification that equips Java applications with an object mapping framework for relational databases. This API furnishes a systematic approach to handling persistence and object-relational mapping. JPA formulates these mappings internally, steering clear of reliance on vendor-specific implementations.

While JPA itself doesn't execute operations autonomously, it leverages ORM (Object Relational Mapping) tools such as TopLink and Hibernate to fulfill its tasks.

JPA outlines the methodology for defining POJOs (Plain Old Java Objects) as entities and effectively managing their relationships through designated meta configurations. These configurations are articulated either through annotations or XML files.

Following are the elements of JPA used for easy persistence management:

• Persistence unit
• EntityManagerFactory
• Persistence context
• EntityManager
• Entity objects

Key Features of JPA

The Java Persistence API (JPA) encompasses the following functionalities:

1. Stored Procedure Query:

   This feature enables the execution of stored procedures without resorting to annotations. The extension of EntityManager via the createStoredProcedureQuery(String procedureName, Class… resultClasses) method facilitates its utilization.

2. Constructor Result Mapping:

   To map query results to existing constructor calls, the @ConstructorResult annotation is employed. This addition supplements the functionality of @SqlResultSetMapping.

3. JPQL Enhancements:

   Enhancements to JPQL comprise the incorporation of new elements such as the following keywords:

   • ON: permits the specification of supplementary join parameters,

   • FUNCTION: facilitates the invocation of database functions, and

   • TREAT: allows for downcasting of entities.

4. Bean Validation:

   Validation requirements can be met by annotating fields with javax.validation.constraints annotations. In cases where validation fails, values are withheld from transmission to the backend.

5. JDBC Properties:

   In JPA 1, vendor-specific properties were the norm, but JPA 2 standardizes them in persistence.xml. Critical properties include:

6. Shared Cache:

   JPA 2 introduces a shared cache mechanism that permits long-lived entities to be stored in the persistence layer for sharing across various contexts. This functionality is accessible through EntityManagerFactory's getCache() method, invoking the standard cache interface.

7. Database Schema Generation:

   Before JPA 2.1, database setup was contingent on vendor-specific parameters in persistence.xml. JPA 2.1 introduces parameters for database setup, including:

8. Mappings:

   JPA 2 enhances mapping capabilities by introducing various new combinations and associations, catering to legacy systems:

   • Element Collections
   • Derived Identifiers
   • Persistently Ordered Lists
   • Unidirectional One-to-Many With No Join Table
   • Orphan Removal
   • Maps
   • Adding a Join Table

Hibernate vs JPA

Advantages of JPA Vs Hibernate

Advantages of JPA

• The creation of definition files is streamlined through the integration of annotations, diminishing the need for extensive code.
• Incorporating diverse implementations can augment the capabilities of the standard version, potentially leading to their incorporation into the JPA specification.
• Employing O/R mapping and database access processing streamlines the programming workload.

Advantages of Hibernate

• Hibernate introduces its query language, known as Hibernate Query Language (HQL), which remains agnostic to specific databases. This ensures the continued functionality of our application even after a database change.
• Hibernate streamlines SQL query composition by offering Dialect classes. This eliminates the need for directly writing SQL queries in Hibernate, as the API provides methods for this purpose.
• Inheritance, associations, and collections are all bolstered by Hibernate.
• While records are being stored in the database, Hibernate can automatically generate primary keys.

Disadvantages of JPA Vs Hibernate

Disadvantages of JPA

• The JPA specification might undergo significant enhancements before achieving stability.
• JPA functions as a specification rather than a product, necessitating a provider to furnish an implementation that enables the utilization of these API standards.

Disadvantages of Hibernate

• For smaller projects with fewer tables, implementing the entire Hibernate framework can be burdensome rather than advantageous.
• Hibernate lacks support for certain queries that are possible with JDBC. Developers must compose separate queries to insert individual objects.
• Hibernate's performance in batch processing is suboptimal, making it advisable to opt for pure JDBC in such scenarios.