java - JPA : Can we use different collection type on either sides of ManyToMany relationship?

Question

我们可以在一个实体中使用 java.util.List 并在相关实体中使用 java.util.Set 来建立 ManyToMany 关系吗？例如:

@Entity
public class Employee {

  @Id
  @Column(name="EMP_ID")
  private long id;
  ...

  @ManyToMany
  @JoinTable(
      name="EMP_PROJ",
      joinColumns={@JoinColumn(name="EMP_ID", referencedColumnName="EMP_ID")},
      inverseJoinColumns={@JoinColumn(name="PROJ_ID", referencedColumnName="PROJ_ID")})
  private Set<Project> projects;
  ...
}

@Entity
public class Project {

  @Id
  @Column(name="PROJ_ID")
  private long id;
  ...

  @ManyToMany(mappedBy="projects")
  private List<Employee> employees;
  ...
}

Answer 1

是的，可以。你为什么不尝试一下呢？

项目可能希望按特定顺序拥有员工，而员工可能只想拥有一组项目。