当前位置： 文江博客话题详情

执行 getFacade().create(current) 时出现 NullPointerException

发布于 2025-01-04 17:18:18 字数 9863 浏览 5 评论 0原文

我的 PujaController.java:

public class PujaController implements Serializable {

private Puja current;
private DataModel items = null;
@EJB
private jpa.sessions.PujaFacade ejbFacade;
private PaginationHelper pagination;
private int selectedItemIndex;

public PujaController() {
}

public Puja getSelected() {
    if (current == null) {
        current = new Puja();
        current.setPujaPK(new jpa.entities.PujaPK());
        selectedItemIndex = -1;
    }
    return current;
}

private PujaFacade getFacade() {
    return ejbFacade;
}


public String creaPuja(Subasta subasta) {
    try {
        current = new Puja();
        current.setPujaPK(new jpa.entities.PujaPK());
        selectedItemIndex = -1;

        current.getPujaPK().setNroDePuja(0); //AUTO_INCREMENT
        Postor postor = AuthenticationPhaseListener.getLoggedInPostor();
        current.getPujaPK().setEmail(postor.getEmail());
        current.getPujaPK().setSubastaId(subasta.getSubastaId());

        Calendar cal = Calendar.getInstance();
        Date now = cal.getTime();
        current.setFechaDePuja(new java.sql.Timestamp(now.getTime()));
        current.setMontoAPagar(BigDecimal.ONE);
        current.setMontoDePuja(BigDecimal.TEN);
        current.setNroDePujas(0);
        current.setPagoAcumulado(BigDecimal.ONE);

        getFacade().create(current);
        JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PujaCreated"));
        return "Puja";
    } catch (Exception e) {
        System.out.println(e);
        JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        return null;
    }
}


public String prepareCreate() {
    current = new Puja();
    current.setPujaPK(new jpa.entities.PujaPK());
    selectedItemIndex = -1;
    return "Create";
}

public String create() {
    try {
        current.getPujaPK().setNroDePuja(0); //AUTO_INCREMENT
        current.getPujaPK().setEmail(current.getPostor().getEmail());
        current.getPujaPK().setSubastaId(current.getSubasta().getSubastaId());
        getFacade().create(current);
        JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PujaCreated"));
        return prepareCreate();
    } catch (Exception e) {
        JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        return null;
    }
}

}

我的 SubastaController.java:

public class SubastaController implements Serializable {

private Subasta current;
private DataModel items = null;
@EJB
private jpa.sessions.SubastaFacade ejbFacade;
private PaginationHelper pagination;
private int selectedItemIndex;

public SubastaController() {
}

public Subasta getSelected() {
    if (current == null) {
        current = new Subasta();
        selectedItemIndex = -1;
    }
    return current;
}

private SubastaFacade getFacade() {
    return ejbFacade;
}


public String preparePuja() {
    current = (Subasta) getItems().getRowData();
    selectedItemIndex = pagination.getPageFirstItem() +    getItems().getRowIndex();
    return "Puja";
}

public String pujar() {
    try {
        getFacade().edit(current);
        JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("SubastaUpdated"));
        PujaController pc = new PujaController();
        pc.creaPuja(current);
        return "Puja";
    } catch (Exception e) {
        JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        return null;
    }
}

public String prepareCreate() {
    current = new Subasta();
    selectedItemIndex = -1;
    return "Create";
}

public String create() {
    try {
        getFacade().create(current);
        JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("SubastaCreated"));
        return prepareCreate();
    } catch (Exception e) {
        JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        return null;
    }
}

}

你好，想学习一些 JSF、EntityManager API，我被困在这里：当执行 pujar() 时，subasta 成功更新，然后 pujaController 中的 creaPuja(current) 是被执行。 creatPuja(current) 没问题，直到 getFacade().create(current);执行并给我一个 NullPointerException。当前对象已创建并设置了密钥。我找不到获取实体管理器引用以成功创建法会的方法。我还包括 Facade java 文件。如果你能提供一些代码来解释这个问题那就太好了！

pujaFacade.java:

public class PujaFacade extends AbstractFacade<Puja> {
@PersistenceContext(unitName = "subasta701WPU")
private EntityManager em;

protected EntityManager getEntityManager() {
    return em;
}

public PujaFacade() {
    super(Puja.class);
}

}

AbstractFacade.java:

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));
}

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

@PostConstruct
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]);
    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();
}

}

这是例外：

INFO: java.lang.NullPointerException
at jsf.PujaController.creaPuja(PujaController.java:146)
at jsf.SubastaController.pujar(SubastaController.java:96)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.sun.el.parser.AstValue.invoke(AstValue.java:234)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:297)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
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:1539)
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 com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
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:662)

是的，getFacade() 为 null。我的问题是如何将当前对象移动或分配给 getFacade()。有一个 PujaFacade 类型的成员 ejbFacade，但我需要 ejbFacade 获取当前（Puja 对象）的值，因此 getFacade 不会为空。谢谢 ...

原文

My PujaController.java:

public class PujaController implements Serializable {

private Puja current;
private DataModel items = null;
@EJB
private jpa.sessions.PujaFacade ejbFacade;
private PaginationHelper pagination;
private int selectedItemIndex;

public PujaController() {
}

public Puja getSelected() {
    if (current == null) {
        current = new Puja();
        current.setPujaPK(new jpa.entities.PujaPK());
        selectedItemIndex = -1;
    }
    return current;
}

private PujaFacade getFacade() {
    return ejbFacade;
}


public String creaPuja(Subasta subasta) {
    try {
        current = new Puja();
        current.setPujaPK(new jpa.entities.PujaPK());
        selectedItemIndex = -1;

        current.getPujaPK().setNroDePuja(0); //AUTO_INCREMENT
        Postor postor = AuthenticationPhaseListener.getLoggedInPostor();
        current.getPujaPK().setEmail(postor.getEmail());
        current.getPujaPK().setSubastaId(subasta.getSubastaId());

        Calendar cal = Calendar.getInstance();
        Date now = cal.getTime();
        current.setFechaDePuja(new java.sql.Timestamp(now.getTime()));
        current.setMontoAPagar(BigDecimal.ONE);
        current.setMontoDePuja(BigDecimal.TEN);
        current.setNroDePujas(0);
        current.setPagoAcumulado(BigDecimal.ONE);

        getFacade().create(current);
        JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PujaCreated"));
        return "Puja";
    } catch (Exception e) {
        System.out.println(e);
        JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        return null;
    }
}


public String prepareCreate() {
    current = new Puja();
    current.setPujaPK(new jpa.entities.PujaPK());
    selectedItemIndex = -1;
    return "Create";
}

public String create() {
    try {
        current.getPujaPK().setNroDePuja(0); //AUTO_INCREMENT
        current.getPujaPK().setEmail(current.getPostor().getEmail());
        current.getPujaPK().setSubastaId(current.getSubasta().getSubastaId());
        getFacade().create(current);
        JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PujaCreated"));
        return prepareCreate();
    } catch (Exception e) {
        JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        return null;
    }
}

}

My SubastaController.java:

public class SubastaController implements Serializable {

private Subasta current;
private DataModel items = null;
@EJB
private jpa.sessions.SubastaFacade ejbFacade;
private PaginationHelper pagination;
private int selectedItemIndex;

public SubastaController() {
}

public Subasta getSelected() {
    if (current == null) {
        current = new Subasta();
        selectedItemIndex = -1;
    }
    return current;
}

private SubastaFacade getFacade() {
    return ejbFacade;
}


public String preparePuja() {
    current = (Subasta) getItems().getRowData();
    selectedItemIndex = pagination.getPageFirstItem() +    getItems().getRowIndex();
    return "Puja";
}

public String pujar() {
    try {
        getFacade().edit(current);
        JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("SubastaUpdated"));
        PujaController pc = new PujaController();
        pc.creaPuja(current);
        return "Puja";
    } catch (Exception e) {
        JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        return null;
    }
}

public String prepareCreate() {
    current = new Subasta();
    selectedItemIndex = -1;
    return "Create";
}

public String create() {
    try {
        getFacade().create(current);
        JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("SubastaCreated"));
        return prepareCreate();
    } catch (Exception e) {
        JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        return null;
    }
}

}

Hi, trying to learn some JSF, EntityManager API, I getting stuck here: When pujar() is executed, the subasta get updated successfully and then the creaPuja(current) in pujaController is executed. The creaPuja(current) is ok until getFacade().create(current); is execute and give me a NullPointerException. The current object is created and the key are set. I do not find the way to get the references to the Entity Manager to get successfully create puja. I include the Facade java file also. If you can provide some code to explain the problem would be great!!!

The pujaFacade.java:

public class PujaFacade extends AbstractFacade<Puja> {
@PersistenceContext(unitName = "subasta701WPU")
private EntityManager em;

protected EntityManager getEntityManager() {
    return em;
}

public PujaFacade() {
    super(Puja.class);
}

}

The abstractFacade.java:

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));
}

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

@PostConstruct
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]);
    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();
}

}

Here is the Exception:

INFO: java.lang.NullPointerException
at jsf.PujaController.creaPuja(PujaController.java:146)
at jsf.SubastaController.pujar(SubastaController.java:96)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.sun.el.parser.AstValue.invoke(AstValue.java:234)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:297)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
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:1539)
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 com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
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:662)

Yes, the getFacade() in null. My question is how I move or assign the current object to getFacade(). There are a member ejbFacade of type PujaFacade, but I need ejbFacade get the value of current (Puja object) so getFacade will not be null. Thank you ...

如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

扫码二维码加入Web技术交流群

发布评论

需要 登录 才能够评论， 你可以免费 注册 一个本站的账号。

评论（1）

初心未许 2025-01-11 17:18:18

抛出异常时 getFacade() 和 current 的值是多少？

另外，您可以发布异常的堆栈跟踪吗？

注意：根据我的经验，NullPointerException 是从 null 对象访问方法的结果。在这种情况下，这意味着 getFacade() 返回 null。

更新：
查看您的代码后我不确定。您从未在 PujaController 或 SubastaController 中设置 ejbFacade，但可以在 SubastaController 中访问它，但不能在 PujaController 中访问它。
尝试将 jpa.sessions.SubastaFacade 实现与 jpa.sessions.PujaFacade 实现进行比较，看看是否缺少任何内容。

例如，PujaFacade 在类定义之前需要 @Stateless 吗？ @PersistenceContext(unitName = "subasta701WPU") 中的单位名称是否应该更改？

您可能还想阅读这些内容：

Java EE 6 应用程序入门

Java 持久性 API - 更简单的编程模型实体持久性

包含一些很好示例的维基百科页面

让我们知道结果如何。

What are the values of getFacade() and current at the point that the exception is thrown.

Also, can you please post the stack trace from the exception.

Note: In my experience NullPointerException are the result of accessing a method from a null object. In this case, that would mean getFacade() is returning null.

Update:
After reviewing your code I am not sure. You never set ejbFacade in PujaController or SubastaController, but are able to access it in SubastaController but not in PujaController.
Try comparing the jpa.sessions.SubastaFacade implementation with the jpa.sessions.PujaFacade implementation and see if you are missing anything.

For example, does PujaFacade need a @Stateless before the class definition? Should the unit name in @PersistenceContext(unitName = "subasta701WPU") be changed?

You may also want to read these:

Getting Started with Java EE 6 Applications

The Java Persistence API - A Simpler Programming Model for Entity Persistence

A Wikipedia page with some good samples

Let us know how it turns out.

回复 原文
~没有更多了~

关于作者

弱骨蛰伏

暂无简介

文章
评论
28 人气
发私信

相关话题

更多

热门标签

操作系统 程序设计 IT运维 Linux系统管理 JavaScript 服务器应用 solaris C/C++ PHP Shell BSD Vue.js aix Oracle Python HTML 系统管理 HTML5 CSS 前端
更多

推荐作者

夢野间

文章 0 评论 0

百度③文鱼

文章 0 评论 0

小草泠泠

文章 0 评论 0

zhuwenyan

文章 0 评论 0

weirdo

文章 0 评论 0

坚持沉默

文章 0 评论 0

更多

友情链接

文江博客
    我们使用 Cookies 和其他技术来定制您的体验包括您的登录状态等。通过阅读我们的 隐私政策 了解更多相关信息。 单击 接受 或继续使用网站，即表示您同意使用 Cookies 和您的相关数据。
    原文