[JPA错误]javax.persistence.EntityNotFoundException: Unable to find xxx

根本原因：由于后来加上的实体、对象在之前的数据没有关联上，所以造成脏数据、故根本的解决方法，就是将之前的测试数据删除，重新添加数据就行了。

问题原因：

无论是@OneToOne 还是@ManyToOne，出现这个原因都是因为子表（被关联表）中没有主表（关联表）中ID所对应的记录。

解决办法：

1. 检查为什么子表中没有主表中ID对应的记录

2. 如果子表中没有主表ID对应的记录也可以正常加载数据，那么需要在主表字段上加一个@NotFound Annotation。示例如下：

@OneToOne(optional=false)
    @JoinColumn(name="business_id")
    @NotFound(action=NotFoundAction.IGNORE)
    private Business business;

这样，当子表中没找到数据时，主表中对应的field就是null，而不会报错了。

从hibernate源码看@NotFound Annotation：

记得NotFound(action=NotFoundAction.IGNORE）会导致Fetch无效，这样的话无论你设置fetchType是lazy还是eager都会以eager加载，一开始我开始模糊的记住，但是过不了2天就会忘，今天有个任务也是配Ignore的，索性就看看里面到底是怎么整的，下面把发现的贴出来：

先看org.hibernate.type.ManyToOneType

[java] view plaincopy

public class ManyToOneType extends EntityType {
private final boolean ignoreNotFound;
public ManyToOneType(String className) {
this( className, false );
}
public ManyToOneType(String className, boolean lazy) {
super( className, null, !lazy, true, false );
this.ignoreNotFound = false;
}

这里可以清楚的看到对ManyToOneType来说默认的是eager加载（前两个红色标注），ignoreNotFound是false，也就是说默认的NotFound不是ignore，即是Exception。

好的，接着往下看org.hibernate.impl.SessionImpl的internalLoad方法：

[java] view plaincopy

public Object internalLoad(String entityName, Serializable id, boolean eager, boolean nullable) throws HibernateException {
// todo : remove
LoadEventListener.LoadType type = nullable ?
LoadEventListener.INTERNAL_LOAD_NULLABLE :
eager ? LoadEventListener.INTERNAL_LOAD_EAGER : LoadEventListener.INTERNAL_LOAD_LAZY;
LoadEvent event = new LoadEvent(id, entityName, true, this);
fireLoad(event, type);
if ( !nullable ) {
UnresolvableObjectException.throwIfNull( event.getResult(), id, entityName );
}
return event.getResult();
}

这里假设你ManyToOne上设置的是NotFoundAction.IGNORE，ignoreNotFound这个属性就会设置为true，掉这个方法时传进来的boolean nullable就是true，这是大前提。

看红色字体的三目运算符，a?b:c,计算规则，先计算a，a为true的话计算b的值返回，a为false计算c的值返回。对a?b:c?d:e这个有点复杂，可以这样换算a?b(c?d:e).也就是说a为false的话计算c？d:e的值返回。

由于nullable是true，咱们就看INTERNAL_LOAD_NULLABLE 这几个常量的值。

下面看org.hibernate.event.LoadEventListener:

[java] view plaincopy

public static final LoadType INTERNAL_LOAD_EAGER = new LoadType("INTERNAL_LOAD_EAGER")
.setAllowNulls(false)
.setAllowProxyCreation(false)
.setCheckDeleted(false)
.setNakedEntityReturned(false);
public static final LoadType INTERNAL_LOAD_LAZY = new LoadType("INTERNAL_LOAD_LAZY")
.setAllowNulls(false)
.setAllowProxyCreation(true)
.setCheckDeleted(false)
.setNakedEntityReturned(false);
public static final LoadType INTERNAL_LOAD_NULLABLE = new LoadType("INTERNAL_LOAD_NULLABLE")
.setAllowNulls(true)
.setAllowProxyCreation(false)
.setCheckDeleted(false)
.setNakedEntityReturned(false);

这里看到 .setAllowProxyCreation(false) 也就是代理创建false，这样话就不是懒加载！！！看到设置为lazy的是.setAllowProxyCreation(true)，设置为eager的是.setAllowProxyCreation(false)，基本能说明eager不创建代理，lazy是代理加载

最后再贴段代码证明哪里调用这布尔值：

org.hibernate.event.def.DefaultLoadEventListener

的proxyOrLoad方法：

[java] view plaincopy

if ( options.isAllowProxyCreation() ) {
return createProxyIfNecessary( event, persister, keyToLoad, options, persistenceContext );
}
else {
// return a newly loaded object
return load(event, persister, keyToLoad, options);
}
}

看hibernate上的注解写的很清楚，如果AllowProxyCreation这布尔值为false的话会返回一个新的加载对象！

详细错误

javax.persistence.EntityNotFoundException:Unable to find com.duona.base.bean.Business with id 1
org.hibernate.ejb.Ejb3Configuration$Ejb3EntityNotFoundDelega<wbr>te.handleEntityNotFound(Ejb3Configuration.java:155)org.hibernate.event.internal.DefaultLoadEventListener<wbr>.load(DefaultLoadEventListener<wbr>.java:210)org.hibernate.event.internal.DefaultLoadEventListener<wbr>.proxyOrLoad(DefaultLoadEventListener<wbr>.java:260)org.hibernate.event.internal.DefaultLoadEventListener<wbr>.onLoad(DefaultLoadEventListener<wbr>.java:148)org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1075)
org.hibernate.internal.SessionImpl.internalLoad(SessionImpl.java:1002)
org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:613)
org.hibernate.type.EntityType.resolve(EntityType.java:441)
org.hibernate.engine.internal.TwoPhaseLoad.doInitializeEntity(TwoPhaseLoad.java:168)org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:134)org.hibernate.loader.Loader.initializeEntitiesAndCol<wbr>lections(Loader.java:999)org.hibernate.loader.Loader.doQuery(Loader.java:878)
org.hibernate.loader.Loader.doQueryAndInitializeNonL<wbr>azyCollections(Loader.java:293)org.hibernate.loader.Loader.doList(Loader.java:2382)
org.hibernate.loader.Loader.doList(Loader.java:2368)
org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2198)
org.hibernate.loader.Loader.list(Loader.java:2193)
org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:470)
org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:355)org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:195)org.hibernate.internal.SessionImpl.list(SessionImpl.java:1244)
org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:257)
com.duona.base.dao.impl.AbstractBaseDaoImpl.query(AbstractBaseDaoImpl.java:146)com.duona.base.service.impl.CashTicketServiceImpl.queryCashTickets(CashTicketServiceImpl.java:144)com.duona.base.web.admin.action.CashTicketAdminAction.searchCashTicketListUI(CashTicketAdminAction.java:82)sun.reflect.NativeMethodAccessorImpl<wbr>.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl<wbr>.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessor<wbr>Impl.invoke(Unknown
Source) java.lang.reflect.Method.invoke(Unknown Source)
com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:453)com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:292)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:255)org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.DefaultWorkflowIntercept<wbr>or.doIntercept(DefaultWorkflowIntercept<wbr>or.java:176)com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)org.apache.struts2.interceptor.validation.AnnotationValidationInte<wbr>rceptor.doIntercept(AnnotationValidationInte<wbr>rceptor.java:68)com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.ConversionErrorIntercept<wbr>or.intercept(ConversionErrorIntercept<wbr>or.java:138)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:236)com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:236)com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.StaticParametersIntercep<wbr>tor.intercept(StaticParametersIntercep<wbr>tor.java:190)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:90)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterce<wbr>ptor.intercept(ScopedModelDrivenInterce<wbr>ptor.java:141)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)org.apache.struts2.interceptor.ServletConfigInterceptor<wbr>.intercept(ServletConfigInterceptor<wbr>.java:164)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:192)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.opensymphony.xwork2.interceptor.ExceptionMappingIntercep<wbr>tor.intercept(ExceptionMappingIntercep<wbr>tor.java:187)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)com.duona.base.web.interceptor.TransactionInterceptor.intercept(TransactionInterceptor.java:17)com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:511)org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteF<wbr>ilter.doFilter(StrutsPrepareAndExecuteF<wbr>ilter.java:91)com.duona.base.web.fifter.PrepareFilter.doFilter(PrepareFilter.java:67)org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)org.apache.coyote.AbstractProtocol$AbstractConnectionHandle<wbr>r.process(AbstractProtocol.java:585)org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1770)java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
java.lang.Thread.run(Unknown Source)