How does the Java Hibernate framework perform persistence operations?

The persistence operations of the Hibernate framework include: creating sessions, saving objects, modifying objects, updating objects, deleting objects, and committing/rolling back transactions. Through these steps, Java objects can interact with relational database tables. For example, the application creates a Person object, calls the save() method to write it to the database, and commits the transaction to confirm the changes.

Persistence operations of Java Hibernate framework

Introduction

Hibernate is a A popular Java ORM (Object Relational Mapping) framework that provides an abstraction layer for mapping between Java objects and relational database tables. A key feature of Hibernate is persistence operations, which enable applications to store and retrieve objects from the database.

Persistence operations

Persistence operations involve the process of storing and retrieving the state of Java objects from a relational database. Hibernate performs these operations through the following steps:

1. Create a session

• Creates a SessionFactory that represents a session to a specific database factory.
• Create a Session object through SessionFactory, which represents a single session.

2. Save the object

• Call the Session.save() method to persist the new object to the database.
• Hibernate will create database tables and columns as needed.

3. Modify the object

• Make changes to the persisted object.
• Hibernate tracks these changes and automatically updates the underlying database.

4. Update the object

• Call the Session.update() method to merge changes to the persistent object into the database middle.

5. Delete the object

• Call the Session.delete() method to delete the object from the database.

6. Commit the transaction

• Start a transaction by calling Session.beginTransaction().
• Commit the transaction to write all pending changes to the database.
• Rollback the transaction to undo all pending changes.

Practical case

Let us illustrate the persistence operation through an example:

// 创建会话工厂
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

// 创建会话
Session session = sessionFactory.openSession();

// 创建一个新的对象
Person person = new Person("John", "Doe");

// 开始事务
session.beginTransaction();

// 保存对象
session.save(person);

// 提交事务
session.getTransaction().commit();

// 关闭会话
session.close();

In the example, Person The object is persisted to the database. Session.save() The method is used to write objects to the database.

Conclusion

Hibernate's persistence operations provide a simple and effective way to interact between Java objects and relational database tables. Applications can easily manage data in the database through the steps of creating a session, saving the object, modifying the object, and committing the transaction.

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