Detailed explanation of the technical principles of the "Hibernate Commons Annotations" framework in the Java class library

Hibernate Commons Annotions is a Java class library that provides some annotations related to Hibernate to simplify developers' configuration (ORM) configuration in the Hibernate framework.The technical principles of the Hibernate Commons Annotations framework will be explained in detail. 1. Notepad summary: Hibernate Commons Annotations contain some annotations closely related to the Hibernate framework, such as@Entity,@Table,@Column, etc.These annotations can be applied to the user -defined Java class and attributes, which are used to specify the mapping relationship between database tables, columns and objects. 2. Hibernate mapping principle: In Hibernate, the transformation between the object and the database by defining the mapping relationship between the physical class and the database table is defined.The Hibernate framework uses metadata to describe these mapping relationships, that is, the mapping relationship of the physical class is defined by the annotation or XML configuration file. 3. Hibernate Commons Annotations technical principles: Hibernate Commons Annotations relies on Java's reflection mechanism to analyze the annotations applied to the physical and attributes, and transform these annotations into the corresponding mapping configuration. (A) Sports comments: By using @Entity annotations on the physical class, Hibernate can identify the physical class as a persistent entity.@Table annotation is used to specify the corresponding database table name and other table level configuration of the physical class. (b) attribute annotation: Hibernate Commons Annotations also provides some attribute -level annotations, such as@ID,@column, etc. @Id annotations are used to specify the primary key attributes of the physical class, and@column annotations are used to specify the mapping relationship between the attribute and the database list. (C) Relationship annotation: Hibernate Commons Annotions also supports annotations of mapping relationships, such as@OneToone,@Onetomany, etc.By using these annotations between the association attributes between the physical classes, Hibernate can automatically generate the corresponding associated tables and external keys. 4. Example code: Below is an example code that uses Hibernate Commons Annotations framework: import javax.persistence.*; @Entity @Table(name = "users") public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @Column(name = "username") private String username; @Column(name = "password") private String password; // Construct function, Getter, and Setter method omitted } In the above code, the@Entity annotation marks the User class as a persistent entity, and@Table annotations specify the corresponding database table name.@ID Note identification ID attributes are the main key,@generateedValue annotation specify the primary key to generate strategy.@Column annotation mappore the username and password properties with the columns in the database table. Summarize: Hibernate Commons Annotions is a convenient Java class library that realizes the Hibernate framework configuration through annotations.By using this framework, developers can simplify the configuration process of object relationship mapping and improve development efficiency.