embeddable types 通常用于将多个 basic type 组合在一起，用在多个 Entity 中。

两个注解

• @javax.persistence.Embeddable - 定义 embeddable types
• @javax.persistence.Embedded - 在 Entity 中引用 embeddable types

package org.example.demo.hibernate;

import javax.persistence.Embeddable;
import javax.persistence.Embedded;
import javax.persistence.Entity;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Persistence;

public class Test {
    public static void main(String[] args) {
        EntityManagerFactory factory = Persistence.createEntityManagerFactory("test");
        EntityManager em = factory.createEntityManager();

        em.getTransaction().begin();
        Person person = new Person();
        person.name = new Name();
        person.name.firstName = "Bruce";
        person.name.lastName = "Lee";
        em.persist(person);
        em.getTransaction().commit();

        em.close();
        factory.close();
    }

    @Entity(name = "Person")
    public static class Person {
        @Id
        @GeneratedValue
        Integer id;
        @Embedded
        Name name;
    }

    @Embeddable
    public static class Name {
        String firstName;
        String lastName;
    }
}

生成 SQL

drop table if exists Person cascade
drop sequence if exists hibernate_sequence

create sequence hibernate_sequence start 1 increment 1
create table Person (id int4 not null, firstName varchar(255), lastName varchar(255), primary key (id))
select nextval ('hibernate_sequence')
insert into Person (firstName, lastName, id) values ('Bruce', 'Lee', 1)

Composition is part of good OO data modeling (idiomatic Java).

所以 embeddable 只是对于 java 来说的，对于 db 没有区别。