java – @Embeddable类可以是私有的吗？

JPA规范中是否有任何描述有效@Embeddable类的内容？我看了但找不到任何东西.

我正在使用带有Hibernate(3.6.4.Final)和Spring(3.0.5)的EclipseLink(2.3.0-M7 – 完整构建字符串2.3.0.v20110429-r9282),并按照EclipseLink/Examples/MOXy/Spring/JAXBAnnotations所记录的方式设置了我的应用程序.其他目前工作,并已持续数月.我正在添加一个@Embeddable类并开始获得NPE.

下面是一些示例代码,我希望有人可以使用它来重现这个,如果它是EclipseLink的一个错误,因为我删除了EclipseLink库和配置(并恢复到Hibernate的实现),然后我不再获得NPE.

测试类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;
        }
    }
}

我有的Spring bean配置是：


(参见上面的XMLHelper类链接)
最后,我将以下内容添加到jaxb.index：

Broken

启动Spring应用程序时,我得到以下异常：

ERROR org.springframework.test.context.TestContextManager 324 - Caught exception while allowing TestExecutionListener [org.springframework.test.context.support.DependencyInjectionTestExecutionListener@9b601d] to prepare test instance [x.y.z.service.AnyTest@198dc19]
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.

如果我将@Embeddable类从private更改为public(并使用EclipseLink),则NPE不再出现.所以我有一个有效的解决方案,但想了解原因.


最佳答案
JPA 2.0 Specification声明可嵌入类必须遵守为实体规定的相同要求.这些要求在说明书的第2.1节中说明,并声明：



The entity class must have a no-arg constructor. It may have other constructors as well. The no-arg constructor must be public or protected.
The entity class must a be top-level    class. An enum or interface must not    not be

  designated as an entity.
The entity class must not be final. No methods or persistent instance variables of the entity class may be final.


因此,我认为影响你的是可嵌入类不是顶级类,加上它是私有的.
你可能想尝试一下.即使这不是原因,您也可以考虑遵循标准的建议,否则,您无法保证您的代码符合它.
 原文链接：https://www.f2er.com/spring/431440.html

java – @Embeddable类可以是私有的吗？

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