EclipseLink无法在OneToMany关系中找到实体

时间:2013-10-03 17:46:26

标签: java jpa persistence eclipselink

我有一个非常简单的eclipse链接案例,我在下面转载。如果我可以让下面的例子工作,那么我可以很容易地将它应用于实际的案例。问题是,我不能!

有两个类 - ParentChild。两者都有String个ID,Parent包含字段Childchildren个对象的列表。 List子项的归因为@OneToMany,两个类都具有@Entity属性。我通过Eclipse将所有内容作为Maven项目运行,persistence.xml存储在src\main\resources\META_INF\persistence.xml中。没有引用其他罐子。

当我致电Persistence.createEntityManagerFactory时,我收到以下异常。似乎认为Child不是一个实体!

Exception in thread "main" Local Exception Stack: 
Exception [EclipseLink-30005] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.PersistenceUnitLoadingException
Exception Description: An exception was thrown while searching for persistence archives with ClassLoader: sun.misc.Launcher$AppClassLoader@1a8e3115
Internal Exception: javax.persistence.PersistenceException: Exception [EclipseLink-28018] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.EntityManagerSetupException
Exception Description: Predeployment of PersistenceUnit [Parent] failed.
Internal Exception: Exception [EclipseLink-7250] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ValidationException
Exception Description: [class com.test.Parent] uses a non-entity [class com.test.Child] as target entity in the relationship attribute [field children].
    at org.eclipse.persistence.exceptions.PersistenceUnitLoadingException.exceptionSearchingForPersistenceResources(PersistenceUnitLoadingException.java:127)
    at org.eclipse.persistence.jpa.PersistenceProvider.createEntityManagerFactoryImpl(PersistenceProvider.java:107)
    at org.eclipse.persistence.jpa.PersistenceProvider.createEntityManagerFactory(PersistenceProvider.java:177)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:79)
    at com.test.Main.main(Main.java:22)
Caused by: javax.persistence.PersistenceException: Exception [EclipseLink-28018] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.EntityManagerSetupException
Exception Description: Predeployment of PersistenceUnit [Parent] failed.
Internal Exception: Exception [EclipseLink-7250] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ValidationException
Exception Description: [class com.test.Parent] uses a non-entity [class com.test.Child] as target entity in the relationship attribute [field children].
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.createPredeployFailedPersistenceException(EntityManagerSetupImpl.java:1950)
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.predeploy(EntityManagerSetupImpl.java:1941)
    at org.eclipse.persistence.internal.jpa.deployment.JPAInitializer.callPredeploy(JPAInitializer.java:98)
    at org.eclipse.persistence.jpa.PersistenceProvider.createEntityManagerFactoryImpl(PersistenceProvider.java:96)
    ... 3 more
Caused by: Exception [EclipseLink-28018] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.EntityManagerSetupException
Exception Description: Predeployment of PersistenceUnit [Parent] failed.
Internal Exception: Exception [EclipseLink-7250] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ValidationException
Exception Description: [class com.test.Parent] uses a non-entity [class com.test.Child] as target entity in the relationship attribute [field children].
    at org.eclipse.persistence.exceptions.EntityManagerSetupException.predeployFailed(EntityManagerSetupException.java:230)
    ... 7 more
Caused by: Exception [EclipseLink-7250] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ValidationException
Exception Description: [class com.test.Parent] uses a non-entity [class com.test.Child] as target entity in the relationship attribute [field children].
    at org.eclipse.persistence.exceptions.ValidationException.nonEntityTargetInRelationship(ValidationException.java:1378)
    at org.eclipse.persistence.internal.jpa.metadata.accessors.mappings.RelationshipAccessor.getReferenceDescriptor(RelationshipAccessor.java:568)
    at org.eclipse.persistence.internal.jpa.metadata.accessors.mappings.RelationshipAccessor.processJoinTable(RelationshipAccessor.java:725)
    at org.eclipse.persistence.internal.jpa.metadata.accessors.mappings.OneToManyAccessor.processManyToManyMapping(OneToManyAccessor.java:198)
    at org.eclipse.persistence.internal.jpa.metadata.accessors.mappings.OneToManyAccessor.process(OneToManyAccessor.java:147)
    at org.eclipse.persistence.internal.jpa.metadata.MetadataProject.processOwningRelationshipAccessors(MetadataProject.java:1578)
    at org.eclipse.persistence.internal.jpa.metadata.MetadataProject.processStage3(MetadataProject.java:1831)
    at org.eclipse.persistence.internal.jpa.metadata.MetadataProcessor.processORMMetadata(MetadataProcessor.java:580)
    at org.eclipse.persistence.internal.jpa.deployment.PersistenceUnitProcessor.processORMetadata(PersistenceUnitProcessor.java:585)
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.predeploy(EntityManagerSetupImpl.java:1865)
    ... 5 more

我已经尝试了很多这方面的事情,我真的不知道下一步该尝试什么。我认为我正在做一些可怕的错误,但谷歌终于解决了自己的问题。任何帮助非常感谢:)

要重现的所有相关文件如下:

父:

package com.test;

import java.util.List;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToMany;

@Entity
public class Parent {
    @Id
    private String      id;
    @OneToMany
    private List<Child> children;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public List<Child> getChildren() {
        return children;
    }

    public void setChildren(List<Child> children) {
        this.children = children;
    }
}

子:

package com.test;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Child {
    @Id
    private String id;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
}

的persistence.xml:

<persistence version="1.0"
    xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.

    <persistence-unit name="Parent">    
        <class>com.test.Parent</class>      
        <properties>        
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>      
            <property name="eclipselink.jdbc.read-connections.min" value="1" />
            <property name="eclipselink.jdbc.write-connections.min" value="1" />
            <property name="eclipselink.jdbc.batch-writing" value="JDBC" />         
            <property name="eclipselink.ddl-generation" value="create-or-extend-tables"/>
            <property name="eclipselink.ddl-generation.output-mode" value="database"/>
            <!-- Logging -->
            <property name="eclipselink.logging.level" value="INFO" />
            <property name="eclipselink.logging.timestamp" value="true" />
            <property name="eclipselink.logging.session" value="true" />
            <property name="eclipselink.logging.thread" value="false" />                                
        </properties>       
    </persistence-unit> 

    <persistence-unit name="Child"> 
        <class>com.test.Child</class>       
        <properties>        
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>      
            <property name="eclipselink.jdbc.read-connections.min" value="1" />
            <property name="eclipselink.jdbc.write-connections.min" value="1" />
            <property name="eclipselink.jdbc.batch-writing" value="JDBC" />         
            <property name="eclipselink.ddl-generation" value="create-or-extend-tables"/>
            <property name="eclipselink.ddl-generation.output-mode" value="database"/>
            <!-- Logging -->
            <property name="eclipselink.logging.level" value="INFO" />
            <property name="eclipselink.logging.timestamp" value="true" />
            <property name="eclipselink.logging.session" value="true" />
            <property name="eclipselink.logging.thread" value="false" />                                
        </properties>       
    </persistence-unit> 


</persistence>

主类(用于测试):

package com.test;

import java.util.HashMap;
import java.util.Map;
import javax.persistence.Persistence;

public class Main {
    private static final String KEY_PERSISTENCE_URL  = "javax.persistence.jdbc.url";
    private static final String KEY_PERSISTENCE_USER = "javax.persistence.jdbc.user";
    private static final String KEY_PERSISTENCE_PASS = "javax.persistence.jdbc.password";

    public static void main(String[] args) {
        Map<String, String> properties = new HashMap<>();
        properties.put(KEY_PERSISTENCE_URL, "jdbc:mysql://localhost:3306/reporting");
        properties.put(KEY_PERSISTENCE_USER, "root");
        properties.put(KEY_PERSISTENCE_PASS, "p4ssw0rd");
        Persistence.createEntityManagerFactory(Parent.class.getSimpleName(), properties);
    }
}

1 个答案:

答案 0 :(得分:5)

使用的持久性单元仅包含单个实体,因此不知道如何持久保存引用的非实体子类。 Child是另一个持久性单元中的实体,但它只是父PU的java对象。这两个单元应合并为一个包含所有依赖实体的单元