由于我正在阅读JPA(Java持久性API)。在那里我读到了Embeddable Classes。所以,我试图在实体类中使用这个概念。但是,在使用这个时,我面临着一个独立实体的问题。在实体中使用嵌入类时传递的分离实体持久化
这里我有Embeddable Class(ZipCode)in Entity。
嵌入类
@Embeddable public class ZipCode {
private String zip;
private String plusFour;
//getter & setter also.
}
实体类
@Entity
@Table(name = "address")
public class Address {
@Id
@GeneratedValue(strategy = IDENTITY)
private long id;
@Embedded
private ZipCode zipCode;
//getter & setter also.
}
我的持久性代码:
@WebServlet("/RegisterServlet")
public class RegisterServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@Inject
private CrudService crudService;
public RegisterServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.getWriter().append("Served at: ").append(request.getContextPath());
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ZipCode z = new ZipCode();
z.setZip("bharti");
z.setPlusFour("rawat");
Address a = new Address();
a.setId(1);
a.setZipCode(z);
try{
crudService.create(a);
}catch(Exception e){
log.info("exception occurs "+ e.getMessage());
}
}
}
我CrudSrvice代码:
@Stateless
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public class CrudServiceImpl implements CrudService {
@PersistenceContext(unitName = "localmedecube")
private EntityManager em;
public CrudServiceImpl() {
// TODO Auto-generated constructor stub
}
@Override
public <T> T create(T t) {
this.em.persist(t);
this.em.flush();
this.em.refresh(t);
return t;
}
@Override
public void delete(@SuppressWarnings("rawtypes") Class type, Object id) {
@SuppressWarnings("unchecked")
Object ref = this.em.getReference(type, id);
this.em.remove(ref);
}
@Override
public <T> T update(T t) {
return this.em.merge(t);
}
}
当我试图坚持我的地址实体它给我的错误是这样
产生的原因:使用javax。 persistence.PersistenceException:org.hibernate.PersistentObjectException:传递给 的分离实体persist:model.Address
请告诉我为什么会发生这种例外。也为我提供适当的答案。
你如何试图坚持下去。你可以分享crudService.create方法 – xxlali
好@xxlali我也共享CRUD代码。 –
嗯,你使用坚持的方法。据我所知,如果你使用持久化方法,你不应该设置对象的id。请删除'a.setId(1);' – xxlali