您需要一个关联表，通常出于各种原因通常在JPA中构建该关联表，主要是为了控制表中的内容，或者在这种情况下映射n路M：N关系。

创建所有实体：

@Entity
public class User {
    @Id @GeneratedValue(strategy=GenerationType.AUTO) 
    private Integer id;
    private String userName;
    @OneToMany(mappedBy="user")
    private Set<UserDepartmentRoleAssociation> associations;
... etc
}

和

@Entity
public class Department {
    @Id @GeneratedValue(strategy=GenerationType.AUTO) 
    private Integer id;
    private String department;
    @OneToMany(mappedBy="department")
    private Set<UserDepartmentRoleAssociation> associations;
    ... etc
}

和

@Entity
public class Role {
    @Id @GeneratedValue(strategy=GenerationType.AUTO) 
    private Integer id;
    private String role;
    ... etc
}

并创建关联表和ID类。

@Entity
public class UserDepartmentRoleAssociation {
    @EmbeddedId private UserDepartmentRoleAssociationId id;
    @ManyToOne @MapsId("userId")
    private User user;
    @ManyToOne @MapsId("departmentId")
    private Department department;
    @ManyToOne @MapsId("roleId")
    private Role role;
    public UserDepartmentRoleAssociation() {
        id = new UserDepartmentRoleAssociationId();
    }
    ... etc
}

和

@Embeddable
public class UserDepartmentRoleAssociationId implements Serializable {
    private Integer userId;
    private Integer departmentId;
    private Integer roleId;
    ... etc
}

并保持一段感情然后…

        User user = new User();
        user.setUserName("user1");

        Department department = new Department();
        department.setDepartment("department 1");

        Role role = new Role();
        role.setRole("Manager");

        UserDepartmentRoleAssociation association = new UserDepartmentRoleAssociation();
        association.setUser(user);
        association.setDepartment(department);
        association.setRole(role);

        em.persist(user);
        em.persist(department);
        em.persist(role);
        em.persist(association);

并通过join fetch读取它

User user = em.createQuery("select u from User u left join fetch u.associations ass left join fetch ass.department left join fetch ass.role where u.id = :id", User.class).setParameter("id", 1).getSingleResult();

请注意，在这些情况下，我使用了in Set而不是Listin
Department，User它引起的问题要少得多。另外，associations当我保留关系时，我也不必创建，因为它UserDepartmentRoleAssociation是拥有实体，因此也可以保留。这些associations集是由JPA在读取记录时创建的。