发现在有状态的ejb扩展中找到的JPA实体不受管理

Question

我认为em.find找到的实体是由em自动管理的,甚至是一个事务,但下面的这个类似乎表明相反.我错了还是班上的错误是什么？

@Stateful
@TransactionAttribute(NOT_SUPPORTED)
public class CustomerGateway {

  @PersistenceContext(unitName = "customersPU", type = EXTENDED)
  private EntityManager em;
  private Customer customer;

  public Customer find(Long id) {
    // customer is not managed!
    this.customer = em.find(Customer.class, id);
    // Print false!
    System.out.println("Method find: " + em.contains(customer));
    // Print false too (2 is the id of an entity)!
    System.out.println("Method find: " + em.contains(em.find(Customer.class, 2L));
    // A workaround
    customer = em.merge(customer);
    // Print true.
    System.out.println("Method find after merge: " + em.contains(customer));
    return this.customer;
  }

编辑1:实体的代码

@Entity
@NamedQuery(name = "Customer.all", query = "select c from Customer c")
public class Customer implements Serializable {
  private static final long serialVersionUID = 1L;
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private Long id;
  private String name;

  public Customer() {
  }

  public Customer(String name) {
    this.name = name;
  }

  public Long getId() {
    return id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  @Override
  public int hashCode() {
    int hash = 0;
    hash += (id != null ? id.hashCode() : 0);
    return hash;
  }

  @Override
  public boolean equals(Object object) {
    // TODO: Warning - this method won't work in the case the id fields are not set
    if (!(object instanceof Customer)) {
      return false;
    }
    Customer other = (Customer) object;
    if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
      return false;
    }
    return true;
  }

  @Override
  public String toString() {
    return "entity.Customer[ id=" + id + " ]";
  }

}

有状态EJB的代码:

@Stateful
@TransactionAttribute(NOT_SUPPORTED)
public class CustomerGateway {

  @PersistenceContext(type = PersistenceContextType.EXTENDED)
  private EntityManager em;

  private Customer customer;

  public Customer getCustomer() {
    return customer;
  }

  public void create(Customer customer) {
    em.persist(customer);
    this.customer = customer;
  }

  public Customer find(Long id) {
    this.customer = em.find(Customer.class, id);
    System.out.println("customer managed ? " + em.contains(this.customer));
    // Workaround :
//    this.customer = em.merge(customer);
    return customer;
  }

  public void remove(Long id) {
    Customer cust = em.getReference(Customer.class, id);
    em.remove(cust);
  }

  @TransactionAttribute(REQUIRES_NEW)
  public void save() {
  }

  public List<Customer> findAllCustomers() {
    Query query = em.createNamedQuery("Customer.all");
    return query.getResultList();
  }

  @Remove
  public void close() {
  }

}

我使用NetBeans 7.4,GlassFish 4.0,EJB 3.2,Java DB.

Answer 1

根据 Checkus 的说法，这似乎是 GF4 中的一个错误： https: //java.net/jira/browse/GLASSFISH-20968