使用Hibernate建模Java类的最佳实践是什么？

Question

I have a question about what would be the best practice for modeling my Java classes and how they should be related in the database. I'm using Spring-Boot and Spring-Data in the project

I have the situation containing professional Administrative, Professional Financial and Professional Developer. Each of them have specific characteristics.

So, I created a Professional class with the attibutos that are common to all employees:

Professional Class

@Entity
@Table(name = "Professional")
@Inheritance(strategy = InheritanceType.JOINED)
public class Professional {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;
    private String age;

    ... getters e setters
}

The other classes, extend from the professional class:

Administrative Class

@Entity
public class Administrative extends Professional {
    private String attribute1;
    private String attribute2;

    ... getters e setters
}

Financial Class

@Entity
public class Financial extends Professional {
    private String attribute1;
    private String attribute2;

    ... getters e setters
}

Developer Class

@Entity
public class Developer extends Professional {
    private String attribute1;
    private String attribute2;

    ... getters e setters
}

Is this the most appropriate way to handle this scenario? Should I use Class Composition instead of Inheritance? Could you please share examples?

Thank you

Answer 1

Inheritance makes more sense here. As an example, composition makes sense where an entity has another entity, eg

class Adult extends Person {
    private List<Animal> pets; // person HAS pets (with are another class)
    private ID identityCard; // person HAS an identity card
}

It wouldn't make sense here for a Person to extend either of Animal or ID because they aren't a subset of either. However, they are a child of the Person class so it makes sense to inherit.

In your case inheritance makes sense because your child classes are a subset of the Professional. You wouldn't say that a Developer has a Professional, but they are a Professional.