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JPA規範中是否有描述有效的@Embeddable類的內容？我看過但找不到任何東西。@Embeddable類可以是私人的嗎？
我使用EclipseLink（2.3.0-M7-完整構建字符串2.3.0.v20110429-r9282）與Hibernate（3.6.4.Final）和Spring（3.0.5），並已建立我的應用程序的記錄在EclipseLink/Examples/MOXy/Spring/JAXBAnnotations。目前所有的東西都可以工作並且持續數月。我正在添加一個@Embeddable類，並開始獲得NPE。
這裏是一些示例代碼，我希望有人可以用它來重現這一點，如果它是EclipseLink的錯誤，因爲我刪除EclipseLink庫和配置（並恢復到Hibernate的實現），那麼我不再獲得NPE。
測試類Broken.java
package x.y.z.model;
import javax.persistence.*;
import javax.xml.bind.annotation.*;
import java.io.Serializable;
@Entity
public class Broken {
@EmbeddedId
private Pk pk = new Pk();
@Embeddable
private static class Pk implements Serializable {
@ManyToOne
private String foo;
public String getFoo() {
return this.foo;
}
public void setFoo(String foo) {
this.foo = foo;
}
}
}
Spring bean配置我的是：
<bean id="jaxbMarshaller" class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
<property name="contextPath" value="x.y.z.model"/>
</bean>
<bean id="xmlHelper" class="x.y.xml.XMLHelper">
<property name="marshaller" ref="jaxbMarshaller"/>
</bean>
（見上面鏈接XMLHelper類）
最後我想補充以下到jaxb.index：
Broken
當啓動Spring應用程序，我得到以下異常：
ERROR org.springframework.test.context.TestContextManager 324 - Caught exception while allowing TestExecutionListener [org.springframewor[email protected]9b601d] to prepare test instance [[email protected]]
java.lang.IllegalStateException: Failed to load ApplicationContext
at org.springframework.test.context.TestContext.getApplicationContext(TestContext.java:308)
at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:109)
at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75)
at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:321)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:220)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:301)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:303)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:240)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:180)
at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:35)
at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:115)
at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:97)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.maven.surefire.booter.ProviderFactory$ClassLoaderProxy.invoke(ProviderFactory.java:103)
at $Proxy0.invoke(Unknown Source)
at org.apache.maven.surefire.booter.SurefireStarter.invokeProvider(SurefireStarter.java:150)
at org.apache.maven.surefire.booter.SurefireStarter.runSuitesInProcess(SurefireStarter.java:91)
at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:69)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jaxbMarshaller' defined in class path resource [applicationContext.xml]: Invocation of init method failed; nested exception is org.springframework.oxm.UncategorizedMappingException: Unknown JAXB exception; nested exception is
javax.xml.bind.JAXBException
- with linked exception:
[java.lang.NullPointerException]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1420)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:580)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:84)
at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:1)
at org.springframework.test.context.TestContext.loadApplicationContext(TestContext.java:280)
at org.springframework.test.context.TestContext.getApplicationContext(TestContext.java:304)
... 31 more
Caused by: org.springframework.oxm.UncategorizedMappingException: Unknown JAXB exception; nested exception is javax.xml.bind.JAXBException
- with linked exception:
[java.lang.NullPointerException]
at org.springframework.oxm.jaxb.Jaxb2Marshaller.convertJaxbException(Jaxb2Marshaller.java:668)
at org.springframework.oxm.jaxb.Jaxb2Marshaller.getJaxbContext(Jaxb2Marshaller.java:335)
at org.springframework.oxm.jaxb.Jaxb2Marshaller.afterPropertiesSet(Jaxb2Marshaller.java:317)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417)
... 44 more
Caused by: javax.xml.bind.JAXBException
- with linked exception:
[java.lang.NullPointerException]
at org.eclipse.persistence.jaxb.JAXBContext$ContextPathInput.createContextState(JAXBContext.java:661)
at org.eclipse.persistence.jaxb.JAXBContext$ContextPathInput.createContextState(JAXBContext.java:621)
at org.eclipse.persistence.jaxb.JAXBContext.<init>(JAXBContext.java:134)
at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:108)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:128)
at javax.xml.bind.ContextFinder.find(ContextFinder.java:249)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:372)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:337)
at org.springframework.oxm.jaxb.Jaxb2Marshaller.createJaxbContextFromContextPath(Jaxb2Marshaller.java:355)
at org.springframework.oxm.jaxb.Jaxb2Marshaller.getJaxbContext(Jaxb2Marshaller.java:328)
... 47 more
Caused by: java.lang.NullPointerException
at org.eclipse.persistence.jaxb.javamodel.Helper.isBuiltInJavaType(Helper.java:261)
at org.eclipse.persistence.jaxb.compiler.AnnotationsProcessor.shouldGenerateTypeInfo(AnnotationsProcessor.java:1526)
at org.eclipse.persistence.jaxb.compiler.AnnotationsProcessor.processClass(AnnotationsProcessor.java:1029)
at org.eclipse.persistence.jaxb.compiler.AnnotationsProcessor.processAdditionalClasses(AnnotationsProcessor.java:994)
at org.eclipse.persistence.jaxb.compiler.AnnotationsProcessor.postBuildTypeInfo(AnnotationsProcessor.java:576)
at org.eclipse.persistence.jaxb.compiler.AnnotationsProcessor.processClassesAndProperties(AnnotationsProcessor.java:230)
at org.eclipse.persistence.jaxb.compiler.Generator.<init>(Generator.java:104)
at org.eclipse.persistence.jaxb.JAXBContext$ContextPathInput.createContextState(JAXBContext.java:658)
... 60 more
如果我改變@Embeddable類從私人到公共（和使用的EclipseLink），該NPE不再發生。所以我有一個解決方案，但想知道爲什麼。
確實很不錯。 +1 – 2011-05-13 11:06:55