以下ping 198.168.57.98 && echo Success || echo failed
下的简洁代码段，
hibernate-entitymanager 5.2.8.Final为什么上次更新必须在下面添加新关系@Entity public class A {
@Id@GeneratedValue private Long id;
@OneToMany(cascade = CascadeType.ALL)
private List<B> b = new ArrayList<B>();
public void add(B b) { this.b.add(b); }
}
@Entity public class B {
@Id@GeneratedValue private Long id;
}
public class Service {
private EntityManagerFactory emf;
private EntityManager em;
private EntityTransaction tx;
public Service() {
emf = Persistence.createEntityManagerFactory("myPU");
em = emf.createEntityManager();
tx = em.getTransaction();
}
public void create(Object obj) {
tx.begin();
em.persist(obj);
tx.commit();
}
public void update(A a, B b) {
tx.begin();
a.add(b);
tx.commit();
}
}
public class ServiceTest {
@Test public void test() {
Service s = new Service();
A a = new A();
s.create(a);
B b1 = new B();
s.update(a, b1);
B b2 = new B();
s.update(a, b2); // reset relation before adding new ?
}
}
之前重置现有关系a_b1？这只是具体实施问题吗？
a_b2@EDIT
它在insert into A (id) values (1);
insert into B (id) values (2);
insert into A_B (A_id, b_id) values (1, 2);
insert into B (id) values (3);
delete from A_B where A_id=1;
insert into A_B (A_id, b_id) values (1, 2);
insert into A_B (A_id, b_id) values (1, 3);
下无法重现，因此可能只是一个实施问题。