Question

我在java ee中真的很棒

我想进行查询以验证电子邮件是否唯一

我在网上搜索后，我得出结论，我的EntityManeger为空

这是我的实体客户，是一个查询 Customer.findByEmail ，这是我的关注点

@Entity
@Table(name = "customer")
@NamedQueries({
@NamedQuery(name = "Customer.findAll", query = "SELECT c FROM Customer c"),
@NamedQuery(name = "Customer.findById", query = "SELECT c FROM Customer c WHERE c.id = :id"),
@NamedQuery(name = "Customer.findByName", query = "SELECT c FROM Customer c WHERE c.name = :name"),
@NamedQuery(name = "Customer.findByEmail", query = "SELECT c FROM Customer c WHERE c.email = :email"),
(...)

我有一个名为CutomerFacade的会话

@Stateless
public class CustomerFacade extends AbstractFacade<Customer> {
@PersistenceContext(unitName = "AffableBeanPU")
public EntityManager em;

public List<Customer> GetPorEmail(String match){
   return  em.createNamedQuery("Customer.findByEmail").setParameter("email", match).getResultList();
}

解决方案是避免在实体管理器中 null

Answer 1

确保您在Java EE服务器中运行并通过容器访问SessionBean。

你在运行什么服务器？你如何访问SessionBean？

在DB中搜索时，EntityManager为null和NullPointerException

1 个答案: