Research on the technical principles of the Persistence API framework in the Java class library

The Persistence API (persistent API) framework in the Java library is a technology used to simplify the interaction between Java applications and databases.It provides a unified interface for data interaction with different databases. By using the concept of object relationship mapping (ORM), the data map in the database table is mapped as the Java object, thereby blocking the details of the underlying database operation. The core principle of the Persistence API framework is to achieve the mapping relationship between the entity class and the database table to realize the states of the data of the data and the status of the state of lasting objects.It allows developers to access and operate databases with simple object -oriented programming styles without writing complex SQL query statements and database connection management code. In the Persistence API framework, developers first need to define the physical class corresponding to the database table.These entity classes usually include data fields to be stored in databases, and specify their mapping relationship with database tables by annotating or XML configuration.For example, you can identify a Java class as a physical class by @Entity annotation, and use @Table annotations to specify the corresponding database table of the physical class, and use @Column annotations to specify the attributes in the physical class and the field mapping in the database table. Next, developers need to configure the environment of the Persistence API framework.This usually includes related configurations such as connection information and transaction management with databases.Through these configurations, the framework can create and manage database connections as needed at runtime.In the configuration file, developers can specify the specific Persistence API implementation framework (such as Hibernate, Eclipseelink, etc.) used. When using the Persistence API framework in the application, the developer can perform the database operation through the API provided by the framework.For example, you can use the EntityManager interface provided by the framework to achieve additional, deletion, and inspection operations of the physical class.Developers can create, modify and delete physical objects through EntityManager, and can also use it to perform query operations.The framework will transform the operation into the SQL statement of the underlying database according to the mapping definition of the physical class, and perform the corresponding database operation. In general, the Persistence API framework simplifies the interaction process between the Java applications and the database, enabling developers to focus more on the implementation of business logic without concerns about the details of the underlying database operation and SQL query statements.It provides a highly abstract programming model that enables developers to access and operate databases in an object -oriented way.This makes the development of applications more efficient and fast, and improves the maintenance and readability of the code.