nicht statische Methode kann nicht aus einem statischen Kontext verwiesen werden, wo T ist ein Variablentyp

Question

Hallo, ich bin neu in EJB (NetBeans), ich versuche, Named Query Property.findAll über mein Servlet abrufen, aber ich habe ein Problem . dies das Problem

nicht statische Methode kann nicht von einem statischen Kontext verwiesen werden, wo T ist eine Art von Variable

AbstractFacade Klasse

public abstract class AbstractFacade<T> { 

    private Class<T> entityClass; 

    public AbstractFacade(Class<T> entityClass) { 
     this.entityClass = entityClass; 
    } 

    protected abstract EntityManager getEntityManager(); 

    public void create(T entity) { 
     getEntityManager().persist(entity); 
    } 

    public void edit(T entity) { 
     getEntityManager().merge(entity); 
    } 

    public void remove(T entity) { 
     getEntityManager().remove(getEntityManager().merge(entity)); 
    } 

    public T find(Object id) { 
     return getEntityManager().find(entityClass, id); 
    } 

    public List<T> findAll() { 
     javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery(); 
     cq.select(cq.from(entityClass)); 
     return getEntityManager().createQuery(cq).getResultList(); 
    } 

    public List<T> findRange(int[] range) { 
     javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery(); 
     cq.select(cq.from(entityClass)); 
     javax.persistence.Query q = getEntityManager().createQuery(cq); 
     q.setMaxResults(range[1] - range[0] + 1); 
     q.setFirstResult(range[0]); 
     return q.getResultList(); 
    } 

    public int count() { 
     javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery(); 
     javax.persistence.criteria.Root<T> rt = cq.from(entityClass); 
     cq.select(getEntityManager().getCriteriaBuilder().count(rt)); 
     javax.persistence.Query q = getEntityManager().createQuery(cq); 
     return ((Long) q.getSingleResult()).intValue(); 
    } 

} 

Klasse Entity (Property)

@Entity 
@Table(name = "property") 
@XmlRootElement 
@NamedQueries({ 
    @NamedQuery(name = "Property.findAll", query = "SELECT p FROM Property p") 
    , @NamedQuery(name = "Property.findByPropertyId", query = "SELECT p FROM Property p WHERE p.propertyId = :propertyId") 
    , @NamedQuery(name = "Property.findByPropertyType", query = "SELECT p FROM Property p WHERE p.propertyType = :propertyType") 
    , @NamedQuery(name = "Property.findByNumOfBedroom", query = "SELECT p FROM Property p WHERE p.numOfBedroom = :numOfBedroom") 
    , @NamedQuery(name = "Property.findByNumOfBathroom", query = "SELECT p FROM Property p WHERE p.numOfBathroom = :numOfBathroom") 
    , @NamedQuery(name = "Property.findByAddress", query = "SELECT p FROM Property p WHERE p.address = :address") 
    , @NamedQuery(name = "Property.findByDescription", query = "SELECT p FROM Property p WHERE p.description = :description") 
    , @NamedQuery(name = "Property.findByFurnish", query = "SELECT p FROM Property p WHERE p.furnish = :furnish") 
    , @NamedQuery(name = "Property.findByGarden", query = "SELECT p FROM Property p WHERE p.garden = :garden") 
    , @NamedQuery(name = "Property.findByArea", query = "SELECT p FROM Property p WHERE p.area = :area") 
    , @NamedQuery(name = "Property.findByBuyType", query = "SELECT p FROM Property p WHERE p.buyType = :buyType") 
    , @NamedQuery(name = "Property.findByPropertyPrice", query = "SELECT p FROM Property p WHERE p.propertyPrice = :propertyPrice")}) 
public class Property implements Serializable { 

    private static final long serialVersionUID = 1L; 
    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    @Basic(optional = false) 
    @Column(name = "PropertyId") 
    private Integer propertyId; 
    @Size(max = 45) 
    @Column(name = "PropertyType") 
    private String propertyType; 
    @Column(name = "NumOfBedroom") 
    private Long numOfBedroom; 
    @Column(name = "NumOfBathroom") 
    private Long numOfBathroom; 
    @Size(max = 250) 
    @Column(name = "Address") 
    private String address; 
    @Size(max = 500) 
    @Column(name = "Description") 
    private String description; 
    @Size(max = 45) 
    @Column(name = "Furnish") 
    private String furnish; 
    @Size(max = 45) 
    @Column(name = "Garden") 
    private String garden; 
    @Column(name = "Area") 
    private Long area; 
    @Size(max = 45) 
    @Column(name = "BuyType") 
    private String buyType; 
    @Column(name = "PropertyPrice") 
    private Integer propertyPrice; 
    @Lob 
    @Column(name = "ImageUrl") 
    private byte[] imageUrl; 
    @OneToMany(mappedBy = "propertyId") 
    private Collection<Offer> offerCollection; 
    @JoinColumn(name = "agentsId", referencedColumnName = "AgentsId") 
    @ManyToOne 
    private Agents agentsId; 
    @JoinColumn(name = "OwnerId", referencedColumnName = "OwnerId") 
    @ManyToOne 
    private Owner ownerId; 

    public Property() { 
    } 

    public Property(Integer propertyId) { 
     this.propertyId = propertyId; 
    } 

    public Integer getPropertyId() { 
     return propertyId; 
    } 

    public void setPropertyId(Integer propertyId) { 
     this.propertyId = propertyId; 
    } 

    public String getPropertyType() { 
     return propertyType; 
    } 

    public void setPropertyType(String propertyType) { 
     this.propertyType = propertyType; 
    } 

    public Long getNumOfBedroom() { 
     return numOfBedroom; 
    } 

    public void setNumOfBedroom(Long numOfBedroom) { 
     this.numOfBedroom = numOfBedroom; 
    } 

    public Long getNumOfBathroom() { 
     return numOfBathroom; 
    } 

    public void setNumOfBathroom(Long numOfBathroom) { 
     this.numOfBathroom = numOfBathroom; 
    } 

    public String getAddress() { 
     return address; 
    } 

    public void setAddress(String address) { 
     this.address = address; 
    } 

    public String getDescription() { 
     return description; 
    } 

    public void setDescription(String description) { 
     this.description = description; 
    } 

    public String getFurnish() { 
     return furnish; 
    } 

    public void setFurnish(String furnish) { 
     this.furnish = furnish; 
    } 

    public String getGarden() { 
     return garden; 
    } 

    public void setGarden(String garden) { 
     this.garden = garden; 
    } 

    public Long getArea() { 
     return area; 
    } 

    public void setArea(Long area) { 
     this.area = area; 
    } 

    public String getBuyType() { 
     return buyType; 
    } 

    public void setBuyType(String buyType) { 
     this.buyType = buyType; 
    } 

    public Integer getPropertyPrice() { 
     return propertyPrice; 
    } 

    public void setPropertyPrice(Integer propertyPrice) { 
     this.propertyPrice = propertyPrice; 
    } 

    public byte[] getImageUrl() { 
     return imageUrl; 
    } 

    public void setImageUrl(byte[] imageUrl) { 
     this.imageUrl = imageUrl; 
    } 

    @XmlTransient 
    public Collection<Offer> getOfferCollection() { 
     return offerCollection; 
    } 

    public void setOfferCollection(Collection<Offer> offerCollection) { 
     this.offerCollection = offerCollection; 
    } 

    public Agents getAgentsId() { 
     return agentsId; 
    } 

    public void setAgentsId(Agents agentsId) { 
     this.agentsId = agentsId; 
    } 

    public Owner getOwnerId() { 
     return ownerId; 
    } 

    public void setOwnerId(Owner ownerId) { 
     this.ownerId = ownerId; 
    } 

    @Override 
    public int hashCode() { 
     int hash = 0; 
     hash += (propertyId != null ? propertyId.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 Property)) { 
      return false; 
     } 
     Property other = (Property) object; 
     if ((this.propertyId == null && other.propertyId != null) || (this.propertyId != null && !this.propertyId.equals(other.propertyId))) { 
      return false; 
     } 
     return true; 
    } 

    @Override 
    public String toString() { 
     return "Entities.Property[ propertyId=" + propertyId + " ]"; 
    } 

} 

Servett Seite

@Override 
    public void init() throws ServletException { 
     List<Property> PropertyList= PropertyFacade.findAll(); 
     getServletContext().setAttribute("property", PropertyList);  

    } 

PropertyFacade Klasse

public class PropertyFacade extends AbstractFacade<Property> { 

    @PersistenceContext(unitName = "testRealPU") 
    private EntityManager em; 

    @Override 
    protected EntityManager getEntityManager() { 
     return em; 
    } 

    public PropertyFacade() { 
     super(Property.class); 
    } 

Answer 1

Da findAll nicht statisch ist, müssen Sie eine Instanz Ihrer PropertyFaçade erstellen. Sie können nicht einfach PropertyFacade.findAll() aufrufen. Im Frühjahr erhalten Sie diese Instanz vom ApplicationContext, nicht sicher, wie sie in ejb erstellt wird.

Hinweis: Beachten Sie die Namenskonvention in Java: Die Variablen beginnen mit Kleinbuchstaben und die Klassen beginnen mit einem Großbuchstaben. Also sollten Sie PropertyList in propertyList ändern.

Answer 2

In Ihrem Servlet Sie wie folgt vor:

@EJB 
PropertyFacade propertyFacade; 

@Override 
public void init() throws ServletException { 
    List<Property> PropertyList= propertyFacade.findAll(); 
    getServletContext().setAttribute("property", PropertyList);  

} 

Und füge @Stateless Anmerkung in Ihrem PropertyFacade.class

@Stateless 
public class PropertyFacade extends AbstractFacade<Property> { 

    @PersistenceContext(unitName = "testRealPU") 
    private EntityManager em; 

    @Override 
    protected EntityManager getEntityManager() { 
     return em; 
    } 

    public PropertyFacade() { 
     super(Property.class); 
    } 
}