java – JPA / Hibernate Embedded id

发布时间：2020-12-14 05:54:23 所属栏目：Java 来源：网络整理

导读：我想做那样的事情：一个对象ReportingFile,可以是LogRequest或LogReport文件. (两者都有相同的结构) 一个对象报告包含一个logRequest,一个带有日期的logReport列表. 我试着设置一个EmbededId,这将是logRequest的一个属性.这就是我遇到的问题.我没有到达mann

我想做那样的事情：

>一个对象ReportingFile,可以是LogRequest或LogReport文件. (两者都有相同的结构)
>一个对象报告包含一个logRequest,一个带有日期的logReport列表.

我试着设置一个EmbededId,这将是logRequest的一个属性.这就是我遇到的问题.我没有到达mannage嵌入式id. (http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#entity-mapping-identifier)

如果你有一个关于我应该怎么做的线索:)

一个例子(不工作)将是：

@Entity
@AssociationOverride( name="logRequest.fileName",joinColumns = { @JoinColumn(name="log_request_file_name") } )
public class Reporting {

    @EmbeddedId
    private ReportingFile logRequest;

    @CollectionOfElements(fetch = FetchType.EAGER)
    @JoinTable(name = "t_reports",schema="",joinColumns = {@JoinColumn(name = "log_report")})
    @Fetch(FetchMode.SELECT)
    private List<ReportingFile> reports;

    @Column(name="generated_date",nullable=true)
    private Date generatedDate;

    [...]
}

@Embeddable
public class ReportingFile {

    @Column(name="file_name",length=255)
    private String fileName;

    @Column(name="xml_content")
    private Clob xmlContent;

    [...]
}

在此示例中,我有以下错误：

15.03.2010 16:37:59 [ERROR] org.springframework.web.context.ContextLoader       Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor#0' defined in class path resource [config/persistenceContext.xml]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [config/persistenceContext.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: test] Unable to configure EntityManagerFactory
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:480)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:221)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:881)
    at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:597)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:366)
    at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:255)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:199)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3843)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4350)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
    at org.apache.catalina.core.StandardService.start(StandardService.java:516)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
    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.catalina.startup.Bootstrap.start(Bootstrap.java:288)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [config/persistenceContext.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: test] Unable to configure EntityManagerFactory
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1337)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:473)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:221)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:308)
    at org.springframework.beans.factory.BeanFactoryUtils.beansOfTypeIncludingAncestors(BeanFactoryUtils.java:270)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.detectPersistenceExceptionTranslators(PersistenceExceptionTranslationInterceptor.java:122)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.<init>(PersistenceExceptionTranslationInterceptor.java:78)
    at org.springframework.dao.annotation.PersistenceExceptionTranslationAdvisor.<init>(PersistenceExceptionTranslationAdvisor.java:70)
    at org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor.setBeanFactory(PersistenceExceptionTranslationPostProcessor.java:97)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1325)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:473)
    ... 29 more
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: test] Unable to configure EntityManagerFactory
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:265)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:125)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83)
    at org.springframework.orm.jpa.LocalEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalEntityManagerFactoryBean.java:91)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:291)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1368)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1334)
    ... 46 more
Caused by: org.hibernate.AnnotationException: A Foreign key refering Reporting from Reporting has the wrong number of column. should be 2
    at org.hibernate.cfg.annotations.TableBinder.bindFk(TableBinder.java:272)
    at org.hibernate.cfg.annotations.CollectionBinder.bindCollectionSecondPass(CollectionBinder.java:1319)
    at org.hibernate.cfg.annotations.CollectionBinder.bindManyToManySecondPass(CollectionBinder.java:1158)
    at org.hibernate.cfg.annotations.CollectionBinder.bindStarToManySecondPass(CollectionBinder.java:600)
    at org.hibernate.cfg.annotations.CollectionBinder$1.secondPass(CollectionBinder.java:541)
    at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:43)
    at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1140)
    at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:319)
    at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1125)
    at org.hibernate.ejb.Ejb3Configuration.buildMappings(Ejb3Configuration.java:1226)
    at org.hibernate.ejb.EventListenerConfigurator.configure(EventListenerConfigurator.java:159)
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:854)
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:191)
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:253)
    ... 52 more

解决方法

好的,我们等着瞧

你有一个@AssociationOverride注释,它的API说：

This annotation is used to override a many-to-one or one-to-one mapping of property or field for an entity relationship.

和

It may be applied to an entity that extends a mapped superclass to override a many-to-one or one-to-one mapping defined by the mapped superclass

在你的问题中,我既没有看过@ManyToOne也没看过@OnoToOne.所以,你的问题有问题.

但是我在StackTrace中看到了以下日志

A Foreign key refering Reporting from Reporting has the wrong number of column. should be 2

你有一个由@EmbeddedId注释定义的复合主键,它有两个属性(fileName和xmlContent)

现在,让我们看看你的@CollectionOfElements

@CollectionOfElements(fetch=FetchType.EAGER)
@JoinTable(name="t_reports",// Your mistake goes here
    joinColumns=@JoinColumn(name="log_report"))
@Fetch(FetchMode.SELECT)
private List<ReportingFile> reports;

它的外键只包含一个属性,而您的复合主键包含两个属性.两者都必须匹配.它解释了为什么你看到这个好消息

A Foreign key refering Reporting from Reporting has the wrong number of column. should be 2

您的正确映射应如下所示

@CollectionOfElements(fetch=FetchType.EAGER)
@JoinTable(name="t_reports",joinColumns={
        // The number of columns defined by our Compound primary key (2)
        // must match the number of columns defined by its Foreign key (2)
        @JoinColumn(name="file_name",referencedColumnName="file_name"),@JoinColumn(name="xml_content",referencedColumnName="xml_content")})
@Fetch(FetchMode.SELECT)
private List<ReportingFile> reports;

还有更多：我不知道您的目标数据库是否支持Clob作为主键.所以记住它.

根据您的回复添加到原始答案

1o第一种情况(没有@CollectionOfElements)

@Entity
public class Reporting {

    // You said you just want a single fileName as primary key
    @Id
    @Column(name="file_name",nullable=false)
    private String fileName;

    // You said you still want to have the whole ReportingFile object
    @Embedded
    private ReportingFile reportingFile;

    @Embeddable
    public static class ReportingFile implements Serializable {

        // You must set up insertable=false,updatable=false
        @Column(name="file_name",insertable=false,updatable=false)
        private String fileName;

        @Column(name="xml_content")
        private Clob xmlContent;

   }

}

请记住以下内容：Hibernate不允许您定义两个共享同一列的属性.因此,我必须在fileName属性中定义insertable = false,updatable = false.

当我做以下事情

Reporting reporting = new Reporting();
reporting.setFileName("home.pdf");

ReportingFile reportingFile = new ReportingFile();
// It will not persisted because of insertable=false,updatable=false
reportingFile.setFileName("home.pdf");
reportingFile.setXmlContent(someClobObject);

session.save(reporting); // It works

2o第一种情况(使用@CollectionOfElements)

@Entity
public class Reporting {

    // You said you just want a single fileName as primary key
    @Id
    @Column(name="file_name",nullable=false)
    private String fileName;

    // You said you still want to have the whole ReportingFile object
    @Embedded
    private ReportingFile reportingFile;

    @CollectionOfElements(fetch=FetchType.EAGER)
    @JoinTable(
        name="t_reports",joinColumns=@JoinColumn(name="file_name",referencedColumnName="file_name",updatable=false))
    private List<ReportingFile> reports;

    @Embeddable
    public static class ReportingFile implements Serializable {

        // You must set up insertable=false,updatable=false)
        private String fileName;

        @Column(name="xml_content")
        private Clob xmlContent;

   }

}

当我做以下事情

Reporting reporting = new Reporting();
reporting.setFileName("home.pdf");

ReportingFile reportingFile = new ReportingFile();
// It will not persisted because of insertable=false,updatable=false
reportingFile.setFileName("home.pdf");
reportingFile.setXmlContent(someClobObject);

reporting.getReports().add(reportingFile);

session.save(reporting); // It does not work

Hibernate会抱怨

repeated column in mapping for collection: reports column: file_name

因此,当您拥有共享外键的@CollectionOfElements时,它将无法按预期工作.但你可以做一个解决方法

@Entity
public class Reporting {

    // You said you just want a single fileName as primary key
    @Id
    @Column(name="file_name",nullable=false)
    private String fileName;

    // You said you still want to have the whole ReportingFile object
    @Embedded
    private ReportingFile reportingFile;

    // Your workaround goes here
    @CollectionOfElements(fetch=FetchType.EAGER)
    @JoinTable(
        name="t_reports",referencedColumnName="file_name"))
    private List<Clob> xmlContents;

    @Transient
    public List<ReportingFile> getReports() {
        List<ReportingFile> reports = new ArrayList<ReportingFile>();

        for(Clob xmlContent: getXmlContents())
            reports.add(new ReportingFile(getFileName(),xmlContent));

        return reports;
    }

    @Embeddable
    public static class ReportingFile implements Serializable {

        // required no-arg  constructor
        public ReportingFile() {}

        public ReportingFile(String fileName,Clob xmlContent) {
            this.fileName = fileName;
            this.xmlContent = xmlContent;
        }

        // You must set up insertable=false,updatable=false)
        private String fileName;

        @Column(name="xml_content")
        private Clob xmlContent;

   }

}

请注意,在您拥有的类中使用时,您可以将@Embeddable类定义为静态.

（编辑：李大同）

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