In-depth technical principles of the Hibernate Commons Annotations framework in the Java library IES)

In -depth discussion on the technical principles of Hibernate Commons Annotations framework in the Java library Brief introduction Hibernate Commons Annotions is a Java class library that implements object relationship mapping (ORM) in the Hibernate framework.It provides a set of annotations that describe the mapping relationship between the Java class and the database table.This article will explore the technical principles of Hibernate Commons Annotations, including the use of annotations and some example code. Technical principle Hibernate Commons Annotions Based on the Java annotation mechanism, object relationship mapping is achieved by adding annotations to the Java class and attributes.The following is the most commonly used annotation in Hibernate Commons any 1. @entity: This annotation is used to mark a Java class as a physical class.The physical class corresponds to a table in the database. 2. @Table: It is used to mappore the table in the physical class and the database.You can set the names of the table, SCHEMA and other attributes. 3. @ID: Used to mark a attribute as the primary key of the physical class. 4. @Column: Used to mappore a column of a attribute with a database table.The names, uniqueness, length and other attributes can be set. 5. @manytoone and @onetomany: These two annotations are used to represent the relationship between entity class.@Manytoone means one -to -one relationship,@Onetomany represents a pair of more relationships. 6. @joincolumn: The outer bond column used to set the relationship between the entity class. Below we will combine several sample code to illustrate the use of Hibernate Commons anymore. Example 1: Mark the physical class @Entity @Table(name = "employees") public class Employee { @Id @Column(name = "id") private int id; @Column(name = "name") private String name; // omit other attributes and methods } Example 2: Related relationship @Entity @Table(name = "departments") public class Department { @Id @Column(name = "id") private int id; @Column(name = "name") private String name; @OneToMany @JoinColumn(name = "department_id") private List<Employee> employees; // omit other attributes and methods } In Example 1, by adding @Entity and @table annotations to the Employee class, the class is marked as a physical class, and it is mapped with the "Employees" table in the database.@Id annotation marker ID attribute is the primary key of the entity class. Example 2 shows the relationship between the two physical classes.By using @Onetomany and @joincolumn annotations in the DEPARTMENT class, a department corresponds to multiple Employee, and JoinColumn specifies the associated key key "department_id". By using Hibernate Commons anymore, we can easily map the Java class and database tables to facilitate the object -relationship mapping. Summarize This article explores the technical principles of the Hibernate Commons Annotations framework, and introduces the commonly used annotations and example code.By using Hibernate Commons anymore, we can simplify the implementation of object relationship mapping.It is hoped that this article can provide readers with basic knowledge about Hibernate Commons Annotations and help them better understand and apply the framework.