在使用JPA持久化时是否需要设置实体类的所有字段？
我试图插入一个有3列的表。这个表的主键是许多表的外键有很多一对多和多对多的关系。试图插入我设置所有这些列，但有一些其他设置我不使用的方法。 当我做em.persist到这个class级时，它会抛出nullpointerexception。 知道为什么会这样做吗？ 我还必须设置其他class级成员吗？
实体类如下
/* * To change this template, choose Tools | Templates * and open the template in the editor. */ package objectRelationalMapping; import java.io.Serializable; import java.util.List; import javax.persistence.*; import javax.validation.constraints.NotNull; import javax.validation.constraints.Size; import javax.xml.bind.annotation.XmlRootElement; import javax.xml.bind.annotation.XmlTransient; /** * * @author jai */ @Entity @Table(name = "entitymain") @XmlRootElement @NamedQueries({ @NamedQuery(name = "Entitymain.findAll", query = "SELECT e FROM Entitymain e"), @NamedQuery(name = "Entitymain.findByUuid", query = "SELECT e FROM Entitymain e WHERE e.uuid = :uuid"), @NamedQuery(name = "Entitymain.findByEntityname", query = "SELECT e FROM Entitymain e WHERE e.entityname = :entityname")}) public class Entitymain implements Serializable { private static final long serialVersionUID = 1L; @Id @Basic(optional = false) @NotNull @Column(name = "uuid") private Integer uuid; @Size(max = 100) @Column(name = "entityname") private String entityname; @JoinTable(name = "successor", joinColumns = { @JoinColumn(name = "emmo_id", referencedColumnName = "uuid")}, inverseJoinColumns = { @JoinColumn(name = "successor_id", referencedColumnName = "uuid")}) @ManyToMany private List entitymainList; @ManyToMany(mappedBy = "entitymainList") private List entitymainList1; @JoinTable(name = "predecessor", joinColumns = { @JoinColumn(name = "emmo_id", referencedColumnName = "uuid")}, inverseJoinColumns = { @JoinColumn(name = "predecessor_id", referencedColumnName = "uuid")}) @ManyToMany private List entitymainList2; @ManyToMany(mappedBy = "entitymainList2") private List entitymainList3; @JoinTable(name = "operation", joinColumns = { @JoinColumn(name = "emmo_id", referencedColumnName = "uuid")}, inverseJoinColumns = { @JoinColumn(name = "operator_id", referencedColumnName = "operator_id")}) @ManyToMany private List operatorsList; @JoinTable(name = "nodes", joinColumns = { @JoinColumn(name = "emmo_id", referencedColumnName = "uuid")}, inverseJoinColumns = { @JoinColumn(name = "node_id", referencedColumnName = "uuid")}) @ManyToMany private List entitymainList4; @ManyToMany(mappedBy = "entitymainList4") private List entitymainList5; @JoinTable(name = "entitytype", joinColumns = { @JoinColumn(name = "uuid", referencedColumnName = "uuid")}, inverseJoinColumns = { @JoinColumn(name = "oid", referencedColumnName = "uuid")}) @ManyToMany private List entitymainList6; @ManyToMany(mappedBy = "entitymainList6") private List entitymainList7; @JoinColumn(name = "entity_kid", referencedColumnName = "entity_kid") @ManyToOne private EntityKind entityKid; @OneToOne(cascade = CascadeType.ALL, mappedBy = "entitymain") private Association association; @OneToMany(cascade = CascadeType.ALL, mappedBy = "targetId") private List associationList; @OneToMany(cascade = CascadeType.ALL, mappedBy = "sourceId") private List associationList1; @OneToMany(cascade = CascadeType.ALL, mappedBy = "entitymain") private List featuresList; @OneToMany(cascade = CascadeType.ALL, mappedBy = "lmpId") private List connectorList; @OneToMany(cascade = CascadeType.ALL, mappedBy = "entitymain") private List attributesList; @OneToMany(cascade = CascadeType.ALL, mappedBy = "entitymain1") private List attributesList1; public Entitymain() { } public Entitymain(Integer uuid) { this.uuid = uuid; } public Integer getUuid() { return uuid; } public void setUuid(Integer uuid) { this.uuid = uuid; } public String getEntityname() { return entityname; } public void setEntityname(String entityname) { this.entityname = entityname; } @XmlTransient public List getEntitymainList() { return entitymainList; } public void setEntitymainList(List entitymainList) { this.entitymainList = entitymainList; } @XmlTransient public List getEntitymainList1() { return entitymainList1; } public void setEntitymainList1(List entitymainList1) { this.entitymainList1 = entitymainList1; } @XmlTransient public List getEntitymainList2() { return entitymainList2; } public void setEntitymainList2(List entitymainList2) { this.entitymainList2 = entitymainList2; } @XmlTransient public List getEntitymainList3() { return entitymainList3; } public void setEntitymainList3(List entitymainList3) { this.entitymainList3 = entitymainList3; } @XmlTransient public List getOperatorsList() { return operatorsList; } public void setOperatorsList(List operatorsList) { this.operatorsList = operatorsList; } @XmlTransient public List getEntitymainList4() { return entitymainList4; } public void setEntitymainList4(List entitymainList4) { this.entitymainList4 = entitymainList4; } @XmlTransient public List getEntitymainList5() { return entitymainList5; } public void setEntitymainList5(List entitymainList5) { this.entitymainList5 = entitymainList5; } @XmlTransient public List getEntitymainList6() { return entitymainList6; } public void setEntitymainList6(List entitymainList6) { this.entitymainList6 = entitymainList6; } @XmlTransient public List getEntitymainList7() { return entitymainList7; } public void setEntitymainList7(List entitymainList7) { this.entitymainList7 = entitymainList7; } public EntityKind getEntityKid() { return entityKid; } public void setEntityKid(EntityKind entityKid) { this.entityKid = entityKid; } public Association getAssociation() { return association; } public void setAssociation(Association association) { this.association = association; } @XmlTransient public List getAssociationList() { return associationList; } public void setAssociationList(List associationList) { this.associationList = associationList; } @XmlTransient public List getAssociationList1() { return associationList1; } public void setAssociationList1(List associationList1) { this.associationList1 = associationList1; } @XmlTransient public List getFeaturesList() { return featuresList; } public void setFeaturesList(List featuresList) { this.featuresList = featuresList; } @XmlTransient public List getConnectorList() { return connectorList; } public void setConnectorList(List connectorList) { this.connectorList = connectorList; } @XmlTransient public List getAttributesList() { return attributesList; } public void setAttributesList(List attributesList) { this.attributesList = attributesList; } @XmlTransient public List getAttributesList1() { return attributesList1; } public void setAttributesList1(List attributesList1) { this.attributesList1 = attributesList1; } @Override public int hashCode() { int hash = 0; hash += (uuid != null ? uuid.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 Entitymain)) { return false; } Entitymain other = (Entitymain) object; if ((this.uuid == null && other.uuid != null) || (this.uuid != null && !this.uuid.equals(other.uuid))) { return false; } return true; } @Override public String toString() { return "objectRelationalMapping.Entitymain[ uuid=" + uuid + " ]"; } } 为了坚持我在一个函数中这样做。我已经为每个创建了对象，并且没有编译错误。这些变量也被设置了。
公共类MapOntology {
@PersistenceContext(unitName = "mmdb-ejbPU") private EntityManager em; Entitymain entitymain = new Entitymain(); EntityKind entitykind = new EntityKind(); EntityKindFacade ekf; public void persistOntology(EntityOntologyBeans objOntology) { //Integer uuid = new Integer(objEntityOntologyBeans.getUuid().getUuid()); // entitykind.setEntityKid(ekf.getkindId(objOntology.getEntitykind())); // em.flush(); entitymain.setUuid(1); entitykind.setEntityKid(2); entitymain.setEntityname(objOntology.getEntityname()); entitymain.setEntityKid(entitykind); em.getTransaction().begin(); em.persist(entitymain); em.getTransaction().commit(); }
它在上面函数的最后一行给出了空指针exception。 请帮忙
堆栈跟踪如下
WARNING: EJB5184:A system exception occurred during an invocation on EJB InsertTransaction, method: public java.lang.String transactions.InsertTransaction.insertOntology() WARNING: javax.ejb.EJBException at com.sun.ejb.containers.BaseContainer.processSystemException(BaseContainer.java:5215) at com.sun.ejb.containers.BaseContainer.completeNewTx(BaseContainer.java:5113) at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:4901) at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:2045) at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1994) at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:222) at com.sun.ejb.containers.EJBLocalObjectInvocationHandlerDelegate.invoke(EJBLocalObjectInvocationHandlerDelegate.java:88) at $Proxy445.insertOntology(Unknown Source) at transactions.__EJB31_Generated__InsertTransaction__Intf____Bean__.insertOntology(Unknown Source) at servlet.NewServlet.processRequest(NewServlet.java:63) at servlet.NewServlet.doPost(NewServlet.java:101) at javax.servlet.http.HttpServlet.service(HttpServlet.java:688) at javax.servlet.http.HttpServlet.service(HttpServlet.java:770) at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231) at com.sun.enterprise.v3.services.impl.ContainerMapper$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 mappingProcess.MapOntology.persistOntology(MapOntology.java:69) at transactions.InsertTransaction.insertOntology(InsertTransaction.java:49) 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 org.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1052) at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1124) at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:5388) at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:619) at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800) at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:571) at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doAround(SystemInterceptorProxy.java:162) at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:144) at sun.reflect.GeneratedMethodAccessor159.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:861) at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800) at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:370) at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:5360) at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:5348) at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:214) ... 31 more SEVERE: javax.ejb.EJBException at com.sun.ejb.containers.BaseContainer.processSystemException(BaseContainer.java:5215) at com.sun.ejb.containers.BaseContainer.completeNewTx(BaseContainer.java:5113) at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:4901) at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:2045) at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1994) at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:222) at com.sun.ejb.containers.EJBLocalObjectInvocationHandlerDelegate.invoke(EJBLocalObjectInvocationHandlerDelegate.java:88) at $Proxy445.insertOntology(Unknown Source) at transactions.__EJB31_Generated__InsertTransaction__Intf____Bean__.insertOntology(Unknown Source) at servlet.NewServlet.processRequest(NewServlet.java:63) at servlet.NewServlet.doPost(NewServlet.java:101) at javax.servlet.http.HttpServlet.service(HttpServlet.java:688) at javax.servlet.http.HttpServlet.service(HttpServlet.java:770) at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231) at com.sun.enterprise.v3.services.impl.ContainerMapper$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 mappingProcess.MapOntology.persistOntology(MapOntology.java:69) at transactions.InsertTransaction.insertOntology(InsertTransaction.java:49) 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 org.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1052) at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1124) at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:5388) at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:619) at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800) at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:571) at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doAround(SystemInterceptorProxy.java:162) at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:144) at sun.reflect.GeneratedMethodAccessor159.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:861) at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800) at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:370) at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:5360) at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:5348) at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:214) ... 31 more SEVERE: at com.sun.ejb.containers.BaseContainer.processSystemException(BaseContainer.java:5215) SEVERE: at com.sun.ejb.containers.BaseContainer.completeNewTx(BaseContainer.java:5113) SEVERE: at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:4901) SEVERE: at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:2045) SEVERE: at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1994) SEVERE: at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:222) SEVERE: at com.sun.ejb.containers.EJBLocalObjectInvocationHandlerDelegate.invoke(EJBLocalObjectInvocationHandlerDelegate.java:88) SEVERE: at $Proxy445.insertOntology(Unknown Source) SEVERE: at transactions.__EJB31_Generated__InsertTransaction__Intf____Bean__.insertOntology(Unknown Source) SEVERE: at servlet.NewServlet.processRequest(NewServlet.java:63) SEVERE: at servlet.NewServlet.doPost(NewServlet.java:101) SEVERE: at javax.servlet.http.HttpServlet.service(HttpServlet.java:688) SEVERE: at javax.servlet.http.HttpServlet.service(HttpServlet.java:770) SEVERE: at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542) SEVERE: at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281) SEVERE: at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) SEVERE: at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655) SEVERE: at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595) SEVERE: at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161) SEVERE: at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331) SEVERE: at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231) SEVERE: at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317) SEVERE: at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195) SEVERE: at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849) SEVERE: at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746) SEVERE: at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045) SEVERE: at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228) SEVERE: at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137) SEVERE: at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104) SEVERE: at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90) SEVERE: at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79) SEVERE: at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54) SEVERE: at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59) SEVERE: at com.sun.grizzly.ContextTask.run(ContextTask.java:71) SEVERE: at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532) SEVERE: at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513) SEVERE: at java.lang.Thread.run(Thread.java:722) SEVERE: Caused by: java.lang.NullPointerException SEVERE: at mappingProcess.MapOntology.persistOntology(MapOntology.java:69) SEVERE: at transactions.InsertTransaction.insertOntology(InsertTransaction.java:49) SEVERE: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) SEVERE: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) SEVERE: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) SEVERE: at java.lang.reflect.Method.invoke(Method.java:601) SEVERE: at org.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1052) SEVERE: at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1124) SEVERE: at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:5388) SEVERE: at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:619) SEVERE: at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800) SEVERE: at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:571) SEVERE: at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doAround(SystemInterceptorProxy.java:162) SEVERE: at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:144) SEVERE: at sun.reflect.GeneratedMethodAccessor159.invoke(Unknown Source) SEVERE: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) SEVERE: at java.lang.reflect.Method.invoke(Method.java:601) SEVERE: at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:861) SEVERE: at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800) SEVERE: at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:370) SEVERE: at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:5360) SEVERE: at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:5348) SEVERE: at com.sun.ejb.containers.EJB
LocalObjectInvocationHandler.invoke（EJBLocalObjectInvocationHandler.java:214）严重：… 31更多
通常，您必须在数据库中调用所有不可为空的列的setter。 如果列可以为null，则不需要为其设置值。 这就像预期的那样。 如果你错过了调用非可空数据库字段的setter，你会看到一个不同的exception。 由于您的代码中存在错误，NPE可能会被抛出。
您只能在托管类上使用注入，例如SessionBeans。 您需要使用Persistence或JNDI查找初始化EntityManager，或使用SessionBean。
您正在使用@PersistenceContext注释注入EntityManager。 只有当您的客户端类MapOntology本身由容器管理时，才能执行此操作。
将其注释为@Stateless应该可以解决问题。
请参阅此答案以获取进一步参考
我终于找到了。 NEP的原因是实体管理器没有被初始化。要初始化它，你必须在声明包含entitymanager的类对象之前编写@EJB注释。它停止给出NEP错误，并且不需要设置所有的成员属性。实体类只是确保设置为非null的列被赋予值（正确）。然后您可以保留它们并插入到数据库中。