Analysis of the technical principles of the Persistence API framework in the Java class library

The Persistence API (persistence API) framework in the Java library is a technology used to manage data interaction between applications and databases.It provides developers with a simple way to map the object into the database table and automatically process data storage, retrieval, update, and delete.This article will in -depth analysis of the technical principles of the Persistence API framework, and provide a complete programming code and related configuration description when necessary. The core principle of the Persistence API framework is the object relationship mapping (ORM).It is mainly composed of the following core components: 1. Sports class: In the Persistence API framework, developers first need to define the physical class.The physical class is the mapping of the domain object, and they ma mapped the database table through the annotation or XML configuration.The entity class usually contains annotations related to attributes, associations and data persistence. 2. Session Factory: The session factory is the key component of the Persistence API framework, which is used to create a session object.The session factory depends on the database configuration and mapping files. It will build a database connection pool based on these configurations, and is responsible for managing the interaction between the persistent objects and the database. 3. Session object: The session object is the core component of the actual database operation.It obtains the database connection through the session factory, and provides a series of methods to handle the addition, deletion, and inspection operation of the persistent objects.Developers can use session objects to perform various database operations, such as saving, querying, updating, and deleting entities. The following is a simple sample code for database operations using the Persistence API framework: // Define the physical class @Entity @Table(name = "users") public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @Column(name = "name") private String name; // omit the constructor, Getter and Setter method } // Create a session factory Configuration configuration = new Configuration().configure(); SessionFactory sessionFactory = configuration.buildSessionFactory(); // Get the session object Session session = sessionFactory.openSession(); Transaction transaction = session.beginTransaction(); // Save the physical object User user = new User(); user.setName("John"); session.save(user); // Query physical object User retrievedUser = session.get(User.class, 1L); // Update the physical object retrievedUser.setName("John Smith"); session.update(retrievedUser); // Delete the physical object session.delete(retrievedUser); // Submit a transaction and close the session transaction.commit(); session.close(); In the above example code, a physical class `user` is first defined, and then created a session factory` sessionFactory`, and then obtain the session objects `session 'through a session factory.Various database operations can be performed through session objects, such as saving, querying, updating, and deleting physical objects.Finally, submit a transaction and close the session. In addition to the above code examples, it also needs to provide database connections and other related configuration information in the configuration file of the application.These configuration information include database URLs, user names, passwords, and mapping relationships between physical and database tables. To sum up, the technical principle of the Persistence API framework is based on ORM ideas. It provides a simple and easy -to -use way to map the object to the database table, and is responsible for handling the data of data storage, retrieval, update, and deletion.Developers only need to define the physical class and configuration files, and use the method provided by the API to perform the database operation.By using the Persistence API framework, developers can focus more on the realization of business logic without needing too much attention to the database interaction details of the bottom layer.