如何在Hibernate中使用单个表连接三个表？

Question

@Entity(name = "A")
@Table(name = "A")
public class A {

       ??? Hibernate Annotation or query
       Map<B,List<C>> BMapC;
}

@Entity(name = "B")
@Table(name = "B")
public class B {
      ...
}

@Entity(name = "C")
@Table(name = "C")
public class C {
      ...
}

Answer 1

不幸的是，hibernate没有为这种场景提供任何现成的注释。只能通过创建到a_b_c的类映射来处理此场景：

@Entity
@Table(name = "A_B_C")
public class name = "A_B_C" {

     @ManyToOne(cascade=CascadeType.ALL)
     @JoinColumn(name = "FK_B", nullable = false)
     private B b;

     @ManyToOne(cascade=CascadeType.ALL)
     @JoinColumn(name = "FK_C", nullable = false)
     private C c;

     //Getters, Setters, other attributes etc.
} 

并在：

 @Entity
 @Table(name = "A")
 public class name = "A" {

          @OneToMany(cascade=CascadeType.ALL)
          @JoinColumn(name = "FK_A", nullable = false)
          private Set<A_B_C> abc;

          //Getters, Setters, other attributes etc.
 } 

并以编程方式将集合abc转换为B,C的映射。