Hibernate mapping refers to the process of defining how the Java objects in an application map to the tables and columns in a relational database. Hibernate uses a variety of annotations and XML configuration files to define these mappings. The most common annotations used for mapping are:
@Entity: Indicates that a class is an entity and should be persisted to the database.
@Id: Indicates the primary key of an entity.
@GeneratedValue: Indicates that the primary key should be generated automatically.
@Column: Specifies the mapping of a property to a specific column in the database table.
@OneToOne: Indicates a one-to-one relationship between entities.
@OneToMany: Indicates a one-to-many relationship between entities.
@ManyToOne: Indicates a many-to-one relationship between entities.
@ManyToMany: Indicates a many-to-many relationship between entities.
Here is an example of how to map a simple entity using Hibernate annotations:
@Entity
public class Employee {
@Id
@GeneratedValue
private int id;
@Column(name = "full_name")
private String name;
private String department;
// getters and setters
}
In this example, the Employee class is annotated with @Entity to indicate that it's an entity that should be persisted to the database. The id property is annotated with @Id and @GeneratedValue to indicate that it's the primary key and should be generated automatically.