What is the architecture of Java Hibernate framework?

Hibernate, as an ORM framework, provides a multi-layer architecture, including SessionFactory, Session, Transaction, Query, Criteria and Entity Manager. In practice, you can use Hibernate to perform CRUD operations, create a connection to the database through SessionFactory, perform operations through Session, manage changes through Transaction, query through Query, build complex query conditions through Criteria, and use Entity Manager for persistence and query. .

Java Hibernate Framework Architecture

Overview

Hibernate is a popular The Java Object Relational Mapping (ORM) framework, which provides a way to map Java objects to database tables. It has a multi-layered architecture as follows:

Architecture

1. SessionFactory

• represents the database Factory class for connection pool.
• Responsible for creating connections and sessions with the database.

2. Session

• represents a single session with the database.
• Provides operations and queries on the database.

3. Transaction

• Abstract transaction unit, used to commit or roll back changes.
• is controlled by Session.

4. Query

• represents database query.
• Used to retrieve and modify data in the database.

5. Criteria

• An advanced query API used to build complex query conditions.
• Based on JPA (Java Persistence API) standard.

6. Entity Manager

• Another optional high-level API.
• Provides persistence and query functions.

Practical case

In the following example, we will use the Hibernate framework to perform basic CRUD (create, read, update, delete) operations:

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class HibernateExample {

    public static void main(String[] args) {
        // 创建一个 Configuration 对象并配置 Hibernate
        Configuration configuration = new Configuration();
        configuration.configure("hibernate.cfg.xml");

        // 创建一个 SessionFactory
        SessionFactory sessionFactory = configuration.buildSessionFactory();

        // 打开一个 Session
        Session session = sessionFactory.openSession();

        // 开始一个 Transaction
        Transaction transaction = session.beginTransaction();

        // 创建一个实体对象
        Employee employee = new Employee("John Doe");

        // 保存实体对象
        session.save(employee);

        // 提交 Transaction
        transaction.commit();

        // 关闭 Session
        session.close();
    }
}

In this example, we create a Configuration object to configure Hibernate, create a SessionFactory, and then open the Session## with the database #. We start a Transaction and then save an Employee entity. Finally, Transaction is submitted and Session is closed.

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