我的 EJB / JPA 项目有问题。我使用 netbeans、weblogic 10g 和 Java EE 应用程序。
我的问题是，我创建“来自数据库的实体类”，然后创建“实体类的会话 bean”，这基本上是我的门面。
然后我回顾了我的战争项目并说“实体类的 JSF 页面”Netbeans 很好地创建了所有类。
一开始它说我必须有一个持久性提供程序，为此我添加了库“Hibernate JPA”。
这是我的 ArchJpaController：
package JPAControllerS;
import JPAControllerS.exceptions.NonexistentEntityException;
import JPAControllerS.exceptions.RollbackFailureException;
import entities.Arch;
import java.io.Serializable;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityNotFoundException;
import javax.persistence.Query;
import javax.transaction.UserTransaction;
public class ArchJpaController implements Serializable {
public ArchJpaController(UserTransaction utx, EntityManagerFactory emf) {
this.utx = utx;
this.emf = emf;
}
private UserTransaction utx = null;
private EntityManagerFactory emf;
public EntityManager getEntityManager() {
return emf.createEntityManager();
}
public void create(Arch arch) throws RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
em.persist(arch);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}
public void edit(Arch arch) throws NonexistentEntityException, RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
arch = em.merge(arch);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
String msg = ex.getLocalizedMessage();
if (msg == null || msg.length() == 0) {
Integer id = arch.getId();
if (findArch(id) == null) {
throw new NonexistentEntityException("The arch with id " + id + " no longer exists.");
}
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}
public void destroy(Integer id) throws NonexistentEntityException, RollbackFailureException, Exception {
EntityManager em = null;
try {
utx.begin();
em = getEntityManager();
Arch arch;
try {
arch = em.getReference(Arch.class, id);
arch.getId();
} catch (EntityNotFoundException enfe) {
throw new NonexistentEntityException("The arch with id " + id + " no longer exists.", enfe);
}
em.remove(arch);
utx.commit();
} catch (Exception ex) {
try {
utx.rollback();
} catch (Exception re) {
throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
}
throw ex;
} finally {
if (em != null) {
em.close();
}
}
}
public List<Arch> findArchEntities() {
return findArchEntities(true, -1, -1);
}
public List<Arch> findArchEntities(int maxResults, int firstResult) {
return findArchEntities(false, maxResults, firstResult);
}
private List<Arch> findArchEntities(boolean all, int maxResults, int firstResult) {
EntityManager em = getEntityManager();
try {
Query q = em.createQuery("select object(o) from Arch as o");
if (!all) {
q.setMaxResults(maxResults);
q.setFirstResult(firstResult);
}
return q.getResultList();
} finally {
em.close();
}
}
public Arch findArch(Integer id) {
EntityManager em = getEntityManager();
try {
return em.find(Arch.class, id);
} finally {
em.close();
}
}
public int getArchCount() {
EntityManager em = getEntityManager();
try {
Query q = em.createQuery("select count(o) from Arch as o");
return ((Long) q.getSingleResult()).intValue();
} finally {
em.close();
}
}
}
这是我的 ArchController：
package JSFClasses;
import entities.Arch;
import JSFClasses.util.JsfUtil;
import JSFClasses.util.PaginationHelper;
import JPAControllerS.ArchJpaController;
import java.io.Serializable;
import java.util.ResourceBundle;
import javax.annotation.Resource;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;
import javax.faces.model.DataModel;
import javax.faces.model.ListDataModel;
import javax.faces.model.SelectItem;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceUnit;
import javax.transaction.UserTransaction;
@ManagedBean(name = "archController")
@SessionScoped
public class ArchController implements Serializable {
@Resource
private UserTransaction utx = null;
@PersistenceUnit(unitName = "IBB_Latest-warPU")
private EntityManagerFactory emf = null;
private Arch current;
private DataModel items = null;
private ArchJpaController jpaController = null;
private PaginationHelper pagination;
private int selectedItemIndex;
public ArchController() {
}
public Arch getSelected() {
if (current == null) {
current = new Arch();
selectedItemIndex = -1;
}
return current;
}
private ArchJpaController getJpaController() {
if (jpaController == null) {
jpaController = new ArchJpaController(utx, emf);
}
return jpaController;
}
public PaginationHelper getPagination() {
if (pagination == null) {
pagination = new PaginationHelper(10) {
@Override
public int getItemsCount() {
return getJpaController().getArchCount();
}
@Override
public DataModel createPageDataModel() {
return new ListDataModel(getJpaController().findArchEntities(getPageSize(), getPageFirstItem()));
}
};
}
return pagination;
}
public String prepareList() {
recreateModel();
return "List";
}
public String prepareView() {
current = (Arch) getItems().getRowData();
selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
return "View";
}
public String prepareCreate() {
current = new Arch();
selectedItemIndex = -1;
return "Create";
}
public String create() {
try {
getJpaController().create(current);
JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ArchCreated"));
return prepareCreate();
} catch (Exception e) {
JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
return null;
}
}
public String prepareEdit() {
current = (Arch) getItems().getRowData();
selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
return "Edit";
}
public String update() {
try {
getJpaController().edit(current);
JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ArchUpdated"));
return "View";
} catch (Exception e) {
JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
return null;
}
}
public String destroy() {
current = (Arch) getItems().getRowData();
selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
performDestroy();
recreatePagination();
recreateModel();
return "List";
}
public String destroyAndView() {
performDestroy();
recreateModel();
updateCurrentItem();
if (selectedItemIndex >= 0) {
return "View";
} else {
// all items were removed - go back to list
recreateModel();
return "List";
}
}
private void performDestroy() {
try {
getJpaController().destroy(current.getId());
JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ArchDeleted"));
} catch (Exception e) {
JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
}
}
private void updateCurrentItem() {
int count = getJpaController().getArchCount();
if (selectedItemIndex >= count) {
// selected index cannot be bigger than number of items:
selectedItemIndex = count - 1;
// go to previous page if last page disappeared:
if (pagination.getPageFirstItem() >= count) {
pagination.previousPage();
}
}
if (selectedItemIndex >= 0) {
current = getJpaController().findArchEntities(1, selectedItemIndex).get(0);
}
}
public DataModel getItems() {
if (items == null) {
items = getPagination().createPageDataModel();
}
return items;
}
private void recreateModel() {
items = null;
}
private void recreatePagination() {
pagination = null;
}
public String next() {
getPagination().nextPage();
recreateModel();
return "List";
}
public String previous() {
getPagination().previousPage();
recreateModel();
return "List";
}
public SelectItem[] getItemsAvailableSelectMany() {
return JsfUtil.getSelectItems(getJpaController().findArchEntities(), false);
}
public SelectItem[] getItemsAvailableSelectOne() {
return JsfUtil.getSelectItems(getJpaController().findArchEntities(), true);
}
@FacesConverter(forClass = Arch.class)
public static class ArchControllerConverter implements Converter {
public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
if (value == null || value.length() == 0) {
return null;
}
ArchController controller = (ArchController) facesContext.getApplication().getELResolver().
getValue(facesContext.getELContext(), null, "archController");
return controller.getJpaController().findArch(getKey(value));
}
java.lang.Integer getKey(String value) {
java.lang.Integer key;
key = Integer.valueOf(value);
return key;
}
String getStringKey(java.lang.Integer value) {
StringBuffer sb = new StringBuffer();
sb.append(value);
return sb.toString();
}
public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
if (object == null) {
return null;
}
if (object instanceof Arch) {
Arch o = (Arch) object;
return getStringKey(o.getId());
} else {
throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + Arch.class.getName());
}
}
}
}
最后我的例外：
java.lang.NullPointerException
at JPAControllerS.ArchJpaController.getEntityManager(ArchJpaController.java:43)
at JPAControllerS.ArchJpaController.findArchEntities(ArchJpaController.java:132)
at JPAControllerS.ArchJpaController.findArchEntities(ArchJpaController.java:128)
at JSFClasses.ArchController$1.createPageDataModel(ArchController.java:66)
at JSFClasses.ArchController.getItems(ArchController.java:166)
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 javax.el.BeanELResolver.getValue(BeanELResolver.java:261)
at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
at com.sun.el.parser.AstValue.getValue(AstValue.java:118)
at com.sun.el.parser.AstEqual.getValue(AstEqual.java:41)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:192)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:413)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1750)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1756)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1759)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1759)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:401)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:134)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:121)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:410)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292)
at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:27)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:43)
at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:43)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3496)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at weblogic.security.service.SecurityManager.runAs(Unknown Source)
at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2180)
at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2086)
at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1406)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:201)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:173)
如果有人可以在这个问题上帮助我，我将不胜感激。