Question

我有JPA实体类：

@XmlRootElement(name = "actor")
@Entity
@Table
@NamedQueries({
@NamedQuery(name = "Actor.getByName", query = "SELECT v FROM Actor v WHERE v.name = :name"),
@NamedQuery(name = "Actor.getAll", query = "SELECT e FROM Actor e")})
public class Actor implements Serializable {
      @Id
      @GeneratedValue(strategy = GenerationType.IDENTITY)
      @Column
      private int id;
      @Column
      private String name;
      @Column
      private String birthDate;
      @Column
      private String email;
      @Column
      private String image;

      //getters and setters here
      //no argument constructor and all arguments constructor
}

DAO Local：

@Local
public interface ActorDaoLocal {
    Actor getActor(int actorId);
    public List<Actor> getAllActors();
}

和DAO：

@Stateless
public class ActorDao implements ActorDaoLocal {
   @PersistenceContext
   private EntityManager em ;

   @Override
   public Actor getActor(int actorId) {
       return em.find(Actor.class, actorId);
   }

   @Override
   public List<Actor> getAllActors() {
      Query named = em.createNamedQuery("Actor.getAll", Actor.class);
      return named.getResultList();
}

在MainController中，我正在调用这些方法：

@Path("/actors")
public class MainController {

   @EJB
   private ActorDaoLocal actorDao;

   @GET
   @Produces({MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML})
   public List<Actor> getAllActors() {
      System.out.println("Getting all actors...");
      List<Actor> actorList = actorDao.getAllActors();
      Actor actor = actorDao.getActor(1);
      System.out.println("actor "  + actor); //this is null
      return actorList; //this is empty list
}

我的问题是Dao方法为getActor方法返回null，为getAllActors方法返回空列表。我在GlassFish工作。与数据库的连接似乎没问题，在Glassfish控制台中我没有看到任何例外情况。当然，我有一些行数据库。

编辑：persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
  <persistence-unit name="ZajacPU" transaction-type="JTA">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
       <property name="javax.persistence.jdbc.url" value="jdbc:derby://localhost:1527/actordb"/>
      <property name="javax.persistence.jdbc.user" value="app"/>
      <property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.ClientDriver"/>
      <property name="javax.persistence.jdbc.password" value="app"/>
      <property name="javax.persistence.schema-generation.database.action" value="create"/>
    </properties>
  </persistence-unit>
 </persistence>

简单的JPA命名查询和EntityManager什么都不返回

0 个答案: