我正在尝试使用以下方法创建思维导图样式的应用程序：
Netbeans 7.2 jdk 6.35 Primefaces 3.4
想法是通过访问数据库并从该数据库生成节点来生成思维导图。我确保程序从与我尝试访问的类型相同的对象生成合适的图形。但是，当我尝试访问数据库信息时，我得到一个NullPointerException。我在生成通用页面时使用的步骤是：
1）创建数据库并填充它们。 2）在netbeans中使用“来自数据库的新实体类”功能。 3）使用“来自实体类的JSF页面”功能。 4）创建一个JSF Managed Bean来生成思维导图。
以下是思维导图Bean的代码：
/*
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* and open the template in the editor.
*/
package jsf;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.enterprise.context.RequestScoped;
import javax.inject.Named;
import jpa.entities.Enginetable;
import jpa.session.EnginetableFacade;
import org.primefaces.event.SelectEvent;
import org.primefaces.model.mindmap.DefaultMindmapNode;
import org.primefaces.model.mindmap.MindmapNode;
/**
*
* @author AOL
*/
@Named(value = "mmBean")
@RequestScoped
public class mmBean {
private MindmapNode root;
private MindmapNode selectedNode;
private List<Enginetable> elements;
private List<Enginetable> filteredElements;
private List<Enginetable> userlist;
private Enginetable selectedElement;
private Enginetable[] selectedElements;
private List<Enginetable> elementlist = new ArrayList<Enginetable>();
private Enginetable nodeentity = new Enginetable();
private Enginetable rootentity = new Enginetable();
private Enginetable userentity = new Enginetable();
private jpa.session.EnginetableFacade ejbFacade;
private static final String[] username;
static{
username = new String[10];
username[0] = "Mercedes";
username[1] = "BMW";
username[2] = "Volvo";
username[3] = "Audi";
username[4] = "Renault";
username[5] = "Opel";
username[6] = "Volkswagen";
username[7] = "Chrysler";
username[8] = "Ferrari";
username[9] = "Ford";
}
/**
* Creates a new instance of MmBean
*/
public mmBean() {
///if(elements==null){
elements = new ArrayList<Enginetable>();
//}
//remoteuser=null;
// this.populateRandomElements(elements, 10);
this.populateRandomElements(elements,6);
// filteredElements = new ArrayList<Graphelement>();
root = new DefaultMindmapNode("Mercedes", "Google", "FFCC00", false);
/*MindmapNode bmw = new DefaultMindmapNode("BMW", "IP Nos", "6e9ebf", true);
MindmapNode volvo = new DefaultMindmapNode("Volvo", "Names", "6e9ebf", true);
MindmapNode audi = new DefaultMindmapNode("Audi", "Malicious ", "6e9ebf", true);
MindmapNode renault = new DefaultMindmapNode("Renault", "IP Nos", "6e9ebf", true);
MindmapNode opel = new DefaultMindmapNode("Opel", "Names", "6e9ebf", true);
MindmapNode volkwagen = new DefaultMindmapNode("Volkswagen", "Malicious ", "6e9ebf", true);
MindmapNode chrysler = new DefaultMindmapNode("Chrysler", "IP Nos", "6e9ebf", true);
MindmapNode ferrari = new DefaultMindmapNode("Ferrari", "Names", "6e9ebf", true);
MindmapNode ford = new DefaultMindmapNode("Ford", "Malicious ", "6e9ebf", true);*/
Object label = root.getLabel();
Enginetable entity;
for( int i = 0 ; i < this.elements.size() ; i++){
entity = this.elements.get(i);
if ( !label.equals(entity.getStartnode() ) && label.equals(entity.getEndnode() ) ) {
root.addNode(new DefaultMindmapNode(entity.getStartnode() , "Malicious Software: ", "00FF99", true));
}
else if ( !label.equals(entity.getStartnode() ) && !label.equals(entity.getEndnode() ) ){
root.addNode(new DefaultMindmapNode(entity.getStartnode() , "Malicious Software: ", "CC0000", true));
}
else if ( label.equals(entity.getStartnode() ) ) {
this.rootentity.setStartnode( entity.getStartnode() );
this.rootentity.setEndnode( entity.getEndnode() );
this.rootentity.setConnections( entity.getConnections() );
this.rootentity.setGroupid( entity.getGroupid() );
this.rootentity.setMoveid( entity.getMoveid() );
this.rootentity.setNewconnectioncost( entity.getNewconnectioncost() );
this.rootentity.setNewinfovalue( entity.getNewinfovalue() );
this.rootentity.setUsername( entity.getUsername() );
this.rootentity.setUserid( entity.getUserid() );
}
}
}
public void setElements(List<Enginetable> elements) {
this.elements = elements;
}
public List<Enginetable> getElements() {
return elements;
}
public void setFilteredElements(List<Enginetable> filteredElements) {
//this.filteredElements = filteredElements;
this.elements=filteredElements;
}
public List<Enginetable> getFilteredElements() {
return filteredElements;
}
public void setSelectedElements(Enginetable[] selectedElements) {
this.selectedElements = selectedElements;
}
public Enginetable[] getSelectedElements() {
return selectedElements;
}
public void setSelectedElement(Enginetable selectedElement) {
this.selectedElement = selectedElement;
}
public Enginetable getSelectedElement() {
return selectedElement;
}
public MindmapNode getRoot() {
return root;
}
public MindmapNode getSelectedNode() {
return selectedNode;
}
public void setSelectedNode(MindmapNode selectedNode) {
this.selectedNode = selectedNode;
}
public void onNodeSelect(SelectEvent event) {
MindmapNode node = (MindmapNode) event.getObject();
for( int i = 0 ; i < this.elements.size() ; i++){
Enginetable entity;
Object label = node.getLabel();
Object rootlabel = this.root.getLabel();
entity = elements.get(i);
if ( entity.getStartnode() == rootlabel ){
this.rootentity = entity;
}
if ( entity.getStartnode() == label ){
this.nodeentity = entity;
}
}
//load children of select node and add via node.addNode(childNode);
//populate if not already loaded
if(node.getChildren().isEmpty()) {
for( int i = 0 ; i < this.elements.size() ; i++){
Enginetable entity;
entity = this.elements.get(i);
if ( (this.nodeentity.getStartnode() == null ? entity.getStartnode() != null : !this.nodeentity.getStartnode().equals(entity.getStartnode())) && (this.nodeentity.getEndnode() == null ? entity.getStartnode() != null : !this.nodeentity.getEndnode().equals(entity.getStartnode())) && (this.rootentity.getEndnode() == null ? entity.getStartnode() == null : this.rootentity.getEndnode().equals(entity.getStartnode())) ) {
node.addNode(new DefaultMindmapNode(entity.getStartnode() , "Malicious Software: ", "33FF00", true));
}
else if ( (this.nodeentity.getStartnode() == null ? entity.getStartnode() != null : !this.nodeentity.getStartnode().equals(entity.getStartnode())) && (this.nodeentity.getEndnode() == null ? entity.getStartnode() == null : this.nodeentity.getEndnode().equals(entity.getStartnode())) && (this.rootentity.getEndnode() == null ? entity.getStartnode() == null : this.rootentity.getEndnode().equals(entity.getStartnode())) ) {
node.addNode(new DefaultMindmapNode(entity.getStartnode() , "Malicious Software: ", "3300FF", true));
}
else if ( (this.nodeentity.getStartnode() == null ? entity.getStartnode() != null : !this.nodeentity.getStartnode().equals(entity.getStartnode())) && (this.nodeentity.getEndnode() == null ? entity.getStartnode() == null : this.nodeentity.getEndnode().equals(entity.getStartnode())) && (this.rootentity.getEndnode() == null ? entity.getStartnode() != null : !this.rootentity.getEndnode().equals(entity.getStartnode())) ) {
node.addNode(new DefaultMindmapNode(entity.getStartnode() , "Malicious Software: ", "FF9900", true));
}
else if ( (this.nodeentity.getStartnode() == null ? entity.getStartnode() != null : !this.nodeentity.getStartnode().equals(entity.getStartnode())) && (this.nodeentity.getEndnode() == null ? entity.getStartnode() != null : !this.nodeentity.getEndnode().equals(entity.getStartnode())) && (this.rootentity.getEndnode() == null ? entity.getStartnode() != null : !this.rootentity.getEndnode().equals(entity.getStartnode())) ) {
node.addNode(new DefaultMindmapNode(entity.getStartnode() , "Malicious Software: ", "CC0000", true));
}
}
}
}
public void onNodeDblselect(SelectEvent event) {
this.selectedNode = (MindmapNode) event.getObject();
}
private EnginetableFacade getFacade() {
return ejbFacade;
}
private void populateRandomElements(List<Enginetable> list, int size) {
userlist = this.getListByUserID( 1 );
for(int i = 0 ; i < size ; i++) {
if ("Chrysler".equals(username[i])){
Random rand = new Random();
Enginetable gel =new Enginetable();
gel.setMoveid(i);
gel.setUserid(i);
gel.setStartnode(username[i]);
gel.setEndnode(username[9]);
gel.setConnections(username[9]);
// gel.setPurpose("dubious");
// gel.setRelationship("naughty");
// gel.setExperimentid(1);
gel.setNewinfovalue(1);
gel.setNewconnectioncost(1);
list.add(gel);
}
else {
Random rand = new Random();
Enginetable gel =new Enginetable();
gel.setMoveid(i);
gel.setUserid(i);
gel.setStartnode(username[i]);
gel.setEndnode(username[9-i]);
gel.setConnections(username[9-i]);
// gel.setPurpose("dubious");
// gel.setRelationship("naughty");
// gel.setExperimentid(1);
gel.setNewinfovalue(1);
gel.setNewconnectioncost(1);
list.add(gel);
}
}
}
//
public Integer getMoveId(Enginetable ent) {
return ent.getMoveid();
}
public void setMoveId(Enginetable ent, Integer id) {
ent.setMoveid(id);
}
public Integer getUserId(Enginetable ent) {
return ent.getMoveid();
}
public void setUserId(Enginetable ent, Integer id) {
ent.setMoveid(id);
}
public String getStartNode(Enginetable ent) {
return ent.getStartnode();
}
public void setStartNode(Enginetable ent, String startnode) {
ent.setStartnode(startnode);
}
public String getEndNode(Enginetable ent) {
return ent.getEndnode();
}
public void setEndNode(Enginetable ent, String endnode) {
ent.setEndnode(endnode);
}
/* public int getExperimentid(Enginetable ent) {
return ent.getExperimentid();
}
public void setExperimentid(Enginetable ent, int experimentid) {
ent.setExperimentid(experimentid);
}*/
public int getNewInfoValue(Enginetable ent) {
return ent.getNewinfovalue();
}
public void setNewInfoValue(Enginetable ent, int totalinfovalue) {
ent.setNewinfovalue(totalinfovalue);
}
public String getConnections(Enginetable ent) {
return ent.getConnections();
}
public void setConnections(Enginetable ent, String connections) {
ent.setConnections(connections);
}
public String getNewConnections(Enginetable ent) {
return ent.getConnections();
}
public void setNewConnections(Enginetable ent, String newconnections) {
ent.setConnections( newconnections );
}
/* public String getUserName(Enginetable ent) {
return ent.getUsername();
}
public void setUsername(Enginetable ent, String name) {
ent.setUsername(name);
}
*/
public List<Enginetable> getListByUsername(String user){
return this.ejbFacade.getEnginetableByUsername(user);
}
public List<Enginetable> getListByUserID( int id ){
if ( this.ejbFacade.getEnginetableByUserid(id) == null){
throw new NullPointerException("admin is null!");
}
else if ( this.ejbFacade.getEnginetableByUserid(id) != null){
List<Enginetable> list = new ArrayList<Enginetable>();
list = this.ejbFacade.getEnginetableByUserid(id);
return list;
}
else{
List<Enginetable> list = new ArrayList<Enginetable>();
Enginetable gel =new Enginetable();
gel.setMoveid(1);
gel.setUserid(1);
gel.setStartnode(username[1]);
gel.setEndnode(username[9]);
gel.setConnections(username[9]);
// gel.setPurpose("dubious");
// gel.setRelationship("naughty");
// gel.setExperimentid(1);
gel.setNewinfovalue(1);
gel.setNewconnectioncost(1);
list.add(gel);
return list;
}
}
}
为了完整起见，我已经包含了它导入的类的代码。
编辑：我删除了Enginetable类，因为我有太多的字符要提交堆栈跟踪。这只是获取和设置方法。
以下是EngineTableFacade类的代码： 包jpa.session;
import java.util.List;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.NoResultException;
import javax.persistence.PersistenceContext;
import jpa.entities.Enginetable;
/**
*
* @author AOL
*/
@Stateless
public class EnginetableFacade extends AbstractFacade<Enginetable> {
@PersistenceContext(unitName = "Networks0.1PU")
private EntityManager em;
@Override
protected EntityManager getEntityManager() {
return em;
}
public EnginetableFacade() {
super(Enginetable.class);
}
public List<Enginetable> getEnginetableByUsername( String username ) {
try {
List<Enginetable> userlist = (List<Enginetable>)
em.createNamedQuery("Enginetable.findByUsername").
setParameter("Username", username).getResultList();
return userlist;
} catch (NoResultException nre) {
return null;
}
}
public List<Enginetable> getEnginetableByUserid( int id ) {
try {
List<Enginetable> userlist = (List<Enginetable>)
em.createNamedQuery("Enginetable.findByUserid").
setParameter("Userid", id).getResultList();
return userlist;
} catch (NoResultException nre) {
return null;
}
}
}
当调用getListByUsername或getListByUserID方法时，抛出NullPointerException，但如果不是，则会正常工作。检查了StackTrace后，这证实了我的想法，即抛出异常的两种方法。
我怀疑，虽然我不确定，这意味着mmBean中的实体管理器为空。我不确定如何，甚至可以纠正这个问题。拜托，任何建议都会非常感激，我对这个我需要跨越但不能跨越的小桥非常困惑和沮丧。谢谢。
编辑包含堆栈跟踪：
com.google.common.collect.ComputationException: java.lang.RuntimeException: java.lang.NullPointerException
at com.google.common.collect.ComputingConcurrentHashMap$ComputingMapAdapter.get(ComputingConcurrentHashMap.java:397)
at org.jboss.weld.bean.proxy.ClientProxyProvider.getClientProxy(ClientProxyProvider.java:102)
at org.jboss.weld.el.AbstractWeldELResolver.lookup(AbstractWeldELResolver.java:115)
at org.jboss.weld.el.AbstractWeldELResolver.getValue(AbstractWeldELResolver.java:96)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:188)
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.AstIdentifier.getValue(AstIdentifier.java:103)
at com.sun.el.parser.AstValue.getValue(AstValue.java:179)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:224)
at org.jboss.weld.el.WeldValueExpression.getValue(WeldValueExpression.java:50)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at org.primefaces.component.mindmap.Mindmap.getValue(Mindmap.java:98)
at org.primefaces.component.mindmap.MindmapRenderer.encodeScript(MindmapRenderer.java:51)
at org.primefaces.component.mindmap.MindmapRenderer.encodeEnd(MindmapRenderer.java:44)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1764)
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:1757)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1760)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:402)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:288)
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:594)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
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:860)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
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)
Caused by: java.lang.RuntimeException: java.lang.NullPointerException
at org.jboss.weld.util.reflection.SecureReflectionAccess.runAsInstantiation(SecureReflectionAccess.java:186)
at org.jboss.weld.util.reflection.SecureReflections.newInstance(SecureReflections.java:341)
at org.jboss.weld.bean.proxy.ProxyFactory.create(ProxyFactory.java:242)
at org.jboss.weld.bean.proxy.ClientProxyProvider.createClientProxy(ClientProxyProvider.java:87)
at org.jboss.weld.bean.proxy.ClientProxyProvider.access$000(ClientProxyProvider.java:43)
at org.jboss.weld.bean.proxy.ClientProxyProvider$1.apply(ClientProxyProvider.java:53)
at org.jboss.weld.bean.proxy.ClientProxyProvider$1.apply(ClientProxyProvider.java:46)
at com.google.common.collect.ComputingConcurrentHashMap$ComputingValueReference.compute(ComputingConcurrentHashMap.java:355)
at com.google.common.collect.ComputingConcurrentHashMap$ComputingSegment.compute(ComputingConcurrentHashMap.java:184)
at com.google.common.collect.ComputingConcurrentHashMap$ComputingSegment.getOrCompute(ComputingConcurrentHashMap.java:153)
at com.google.common.collect.ComputingConcurrentHashMap.getOrCompute(ComputingConcurrentHashMap.java:69)
at com.google.common.collect.ComputingConcurrentHashMap$ComputingMapAdapter.get(ComputingConcurrentHashMap.java:393)
... 52 more
Caused by: java.lang.NullPointerException
at jsf.mmBean.getListByUserID(mmBean.java:360)
at jsf.mmBean$Proxy$_$$_WeldClientProxy.getListByUserID(mmBean$Proxy$_$$_WeldClientProxy.java)
at jsf.mmBean.populateRandomElements(mmBean.java:277)
at jsf.mmBean.<init>(mmBean.java:74)
at jsf.mmBean$Proxy$_$$_WeldClientProxy.<init>(mmBean$Proxy$_$$_WeldClientProxy.java)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at java.lang.Class.newInstance0(Class.java:355)
at java.lang.Class.newInstance(Class.java:308)
at org.jboss.weld.util.reflection.SecureReflections$16.work(SecureReflections.java:344)
at org.jboss.weld.util.reflection.SecureReflectionAccess.run(SecureReflectionAccess.java:52)
at org.jboss.weld.util.reflection.SecureReflectionAccess.runAsInstantiation(SecureReflectionAccess.java:173)
... 63 more
答案 0 :(得分：2)
您需要将ejb注入bean
@EJB
private jpa.session.EnginetableFacade ejbFacade;
你的mmBean发现了一些问题，构造函数中的东西应该被移动到postConstruct方法中（因为它是在注入EJB后调用的）
@PostConstruct
public void init() {
... (code from constructor here)
}