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我有空指针异常，我不知道为什么。在 DB 中，我有一张这样的表格（lekarz 在波兰语中是医生的意思）：

create table Lekarz(
idlekarz int unique not null primary key,
poziom int not null references Poziom_dostepu(idpoziom),
specjalnosc varchar(50) not null);

这是实体类：

@Entity
@Table(name = "lekarz")
@DiscriminatorValue("lekarz")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "Lekarz.findAll", query = "SELECT l FROM Lekarz l"),
    @NamedQuery(name = "Lekarz.findById", query = "SELECT l FROM Lekarz l WHERE l.idpoziom = :idpoziom"),
    @NamedQuery(name = "Lekarz.findBySpecjalnosc", query = "SELECT l FROM Lekarz l WHERE l.specjalnosc = :specjalnosc")})
public class Lekarz extends PoziomDostepu implements Serializable {
    private static final long serialVersionUID = 1L;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 50)
    @Column(name = "specjalnosc")
    private String specjalnosc;
    @JoinColumn(name = "idpoziom", referencedColumnName = "idpoziom")
    @ManyToOne(optional = false)
    private PoziomDostepu poziom;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "lekarz")
    private Collection<Pacjent> pacjentCollection;
    @JoinColumn(name = "osoba", referencedColumnName = "idosoba")
    @OneToOne(optional = false)
    private Osoba osoba;

    public Lekarz() {
    }

    public Osoba getOsoba() {
        return osoba;
    }

    public void setOsoba(Osoba osoba) {
        this.osoba = osoba;
    }

    public String getSpecjalnosc() {
        return specjalnosc;
    }

    public void setSpecjalnosc(String specjalnosc) {
        this.specjalnosc = specjalnosc;
    }

    public PoziomDostepu getPoziom() {
        return poziom;
    }

    public void setPoziom(PoziomDostepu poziom) {
        this.poziom = poziom;
    }

    @XmlTransient
    public Collection<Pacjent> getPacjentCollection() {
        return pacjentCollection;
    }

    public void setPacjentCollection(Collection<Pacjent> pacjentCollection) {
        this.pacjentCollection = pacjentCollection;
    }

    @Override
    public String toString() {
        return "pl.karta.epacjent.entities.Lekarz[ idlekarz=" + idpoziom + " ]";
    }

}

正面：

@Stateless
public class LekarzFacade extends AbstractFacade<Lekarz> implements LekarzFacadeLocal {
    @PersistenceContext(unitName = "epacjentPU")
    private EntityManager em;

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

    public LekarzFacade() {
        super(Lekarz.class);
    }



}

局部立面：

@Local
public interface LekarzFacadeLocal {
    void create(Lekarz Lekarz);
    void edit(Lekarz konto);  
    void remove(Lekarz konto);
    Lekarz find(Object id);
    List<Lekarz> findAll();
    List<Lekarz> findRange(int[] range);
    int count();
}

抽象外观中的函数 findAll()：

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

我只是在bean中有这样的功能：

public List<Lekarz> getListaLekarzy()
    {
          return lekarzfacade.findAll();
    }

空指针是因为这个函数（getListaLekarzy），但我确定 DB 中的 Lekarz 表中有 1 条记录，所以我应该得到这个记录的 1 元素列表。我对吗？

提前感谢所有帮助。

编辑 1：lekarzBean 中的门面：

@Stateless
@LocalBean
@ManagedBean(name = "LekarzBean")
@SessionScoped
public class LekarzBean {

    @EJB
    private EndpointLocal endpoint;
    private LekarzFacadeLocal lekarzfacade;

堆栈跟踪

javax.faces.el.EvaluationException: java.lang.NullPointerException
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102)
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
    at javax.faces.component.UICommand.broadcast(UICommand.java:315)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
    at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.NullPointerException
    at pl.karta.epacjent.beans.ListaPacjentowBean.getListaLekarzy(ListaPacjentowBean.java:52)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at javax.el.BeanELResolver.invokeMethod(BeanELResolver.java:779)
    at javax.el.BeanELResolver.invoke(BeanELResolver.java:528)
    at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:257)
    at com.sun.el.parser.AstValue.invoke(AstValue.java:248)
    at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:302)
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
    ... 32 more
4

1 回答 1

2

添加@EJB注释到private LekarzFacadeLocal lekarzfacade; 

@EJB
private EndpointLocal endpoint;  
@EJB
private LekarzFacadeLocal lekarzfacade;
于 2013-01-18T14:10:54.343 回答