在Hibernate中没有主键的情况下从表中获取实体

@Entity
@Table(name = "orders")
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    // 其他属性...

    @OneToMany
    @JoinColumn(name = "order_id")
    private List<OrderItem> items;

    // getter和setter方法...
}

@Entity
@Table(name = "order_items")
public class OrderItem {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    // 其他属性...

    @ManyToOne
    @JoinColumn(name = "order_id")
    private Order order;

    // getter和setter方法...
}

OrderItem item = session.get(OrderItem.class, itemId);
Order order = item.getOrder();