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

[JPA] javax.persistence.EntityNotFoundException: Unable to find com.duona.base.bean.Business with id 1

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

 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：  

 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:   

 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：

 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$Ejb3EntityNotFoundDelegate.handleEntityNotFound(Ejb3Configuration.java:155) org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:210) org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:260) org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.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.initializeEntitiesAndCollections(Loader.java:999) org.hibernate.loader.Loader.doQuery(Loader.java:878) org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(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.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.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.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.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.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249) com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.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.StaticParametersInterceptor.intercept(StaticParametersInterceptor.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.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.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.intercept(ServletConfigInterceptor.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.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.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.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.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$AbstractConnectionHandler.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)