Join more than two tables using Annotations in Spring Data JPA

Question

I've three entities: A, B and C, and the relation between them is as following:

class A{
    @ManyToMany
    List<B> bs;
    //other attributes and getter setters
}

class B{

    @ManyToMany
    List<C> cs;
    //other attributes and getter setters
}

class C{
    //other attributes and getter setters
}

But from my current entity classes, I can make relation between any 2 tables using @JoinTable. But what I want is to save relation between all 3 entities in a separate table, having primary keys of these entities as columns. (Foreign keys)

If we assume entities B and C are already saved (inserted) into database and I insert new entity of A as following:

A:{
  "A_id": 1
  B:[
    "B_id": 1
    {
      C:[
          {"C_id": 1}, {"C_id": 2}
        ]
    }, 
    {
      "B_id": 2
      C:[
          {"C_id": 2}
        ]
     }
  ]
}

Then A should be saved in it's table and the relations should be listed in a separate table as following:

A_id    B_id    C_id
=====================
 1       1       1
 1       1       2
 1       2       2

One of the related question I've seen here. But I think my scenario is different as I've many to many relations between all the entities A, B and C.

I'm not asking for full code. Any approach or exact reference will be fine as long as it solves the purpose. Thanks

EDIT:

I've tried implementing the separate relation table as mentioned in the answer. But the problem with this approach is that, when I remove a row from the relation table, It also removes the entry from the join table of B and C. (Affects the previous relation of entities B and C)

Also while updating updating the row, it changes (performs insert) into the join table of entity B and C. Which is not expected behavior. I want this table for just storing the relation between the entities and not for changing previous relations between those entities.

Following is my new relation table:

@Entity
@Table(name = "relation_table")
public class RelationEntity {

    @Id
    @Column(name = "pk_relation_id")
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Integer relatoinId;

    @OneToOne
    @JoinColumn(name = "a_id")
    private A a;

    @OneToOne
    @JoinColumn(name = "b_id")
    private B b;

    @OneToOne
    @JoinColumn(name = "c_id")
    private C c;

    //getter and setters
}

Answer 1

If you want to keep the relation in separate table then you can simply do something like this to save primary keys

@Entity
@Table(name = "relation_bridge")
public class RelationBridge {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @ManyToOne
    @JoinColumn(name = "a")
    private A a;

    @ManyToOne
    @JoinColumn(name = "b")
    private B b;

    @ManyToOne
    @JoinColumn(name = "c")
    private C c;

    //getters & setters
}

EDIT

When I remove a row from the relation table, It also removes the entry >from the join table of B and C. (Affects the previous relation of >entities B and C)

The above solution should not delete the entries in a parent table unless explicitly defined. However you may be using other mappings in your other classes so this behavior can be controlled by applying Cascading in your mappings.

A Beginner's Guide to JPA and Hibernate Cascade Types

Good read for beginners