无法构建Hibernate SessionFactory；嵌套异常

Question

@Entity
public class A {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private Set<B> b=new HashSet<>();
    public A() {

    }
}

@Entity
public class B {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private Set<A> a=new HashSet<>();
    public B() {

    }

}

Answer 1

A：

@Entity
public class A {
    ...
    @ManyToMany(cascade = CascadeType.ALL)//don't use fetch here
    private List<B> b=new ArrayList<>();
}

B：

@Entity
public class B {
    ...
    @ManyToMany(cascade = CascadeType.ALL)//don't use fetch here
    private List<A> a=new ArrayList<>();
}

不要在OneToMany或ManyToMany上使用fetch，意思是*tomany