Question

我正在尝试创建在eclipse中连接到derby数据库的web应用程序。我在项目方面添加了JPA方面。当我尝试从实体生成表时，我收到错误。这是stacktrace的第一位：

using System;
using System.IO;
using System.IO.Compression;

namespace ConsoleApplication
{
    class Program`enter code here`
    {
        static void Main(string[] args)
        {
            using (FileStream zipToOpen = new FileStream(@"c:\users\exampleuser\release.zip", FileMode.Open))
            {
                using (ZipArchive archive = new ZipArchive(zipToOpen, ZipArchiveMode.Update))
                {
                    ZipArchiveEntry readmeEntry = archive.CreateEntry("Readme.txt");
                    using (StreamWriter writer = new StreamWriter(readmeEntry.Open()))
                    {
                            writer.WriteLine("Information about this package.");
                            writer.WriteLine("========================");
                    }
                }
            }
        }
    }
}

以下是代码：

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: org.eclipse.persistence.dynamic.DynamicClassLoader@2a742aa2
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 [lv10example] failed.
Internal Exception: Exception [EclipseLink-7250] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ValidationException
Exception Description: [class ba.fet.rwa.lv10.domain.Answer] uses a non-entity [class ba.fet.rwa.lv10.domain.Question] as target entity in the relationship attribute [field listOfQuestions].
    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 org.eclipse.jpt.jpa.eclipselink.core.ddlgen.Main.buildEntityManagerFactory(Main.java:94)
    at org.eclipse.jpt.jpa.eclipselink.core.ddlgen.Main.execute(Main.java:80)
    at org.eclipse.jpt.jpa.eclipselink.core.ddlgen.Main.main(Main.java:68)
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 [lv10example] failed.

这是另一个类：

    @Entity
    public class Answer {
        @Id
        @GeneratedValue(strategy=GenerationType.TABLE)
        @Column(name = "id")
        private int id;
        private String text;
        private boolean correctStatus;
        @ManyToMany(cascade = CascadeType.PERSIST)
        @JoinTable(name="QuestionAnswer",joinColumns=@JoinColumn(name="answerID", 
   referencedColumnName="id"), inverseJoinColumns=@JoinColumn(name="questionID",
   referencedColumnName="id"))

    private Collection<Question> listOfQuestions;

    public Answer() {
        id=0;
        text="";
        correctStatus=false;
        listOfQuestions=null;
    }

    public Answer(int _id, String _text, boolean _correctStatus,Question question){
        id=_id;
        text=_text;
        correctStatus=_correctStatus;
        listOfQuestions.add(question);
    }
    ... Getters and setters ...

}

这是persistence.xml

@Entity
@Table(schema = "TEST")
public class Question {
    @Id
    @GeneratedValue(strategy=GenerationType.TABLE)
    @Column(name = "id")
    private int id;
    private String text;
    private boolean answered;
    private int points;

    @ManyToMany(mappedBy="listOfQuestions")
    private Collection<Quiz> listOfQuizzes;

    @ManyToMany(mappedBy="listOfQuestions")
    private Collection<Answer> listOfAnswers;

    public Question() {
        id=0;
        text="";
        answered=false;
        points=0;
        listOfAnswers=null;
    }

    public Question(int _id,String _text, int _points,Answer answer){

        id=_id;
        text=_text;
        answered=false;
        points=_points;
        listOfAnswers.add(answer);
    }

    ... Getters and setters ...

}

有人可以帮我吗？这里肯定有错误，但我找不到它。也许这是jpa facet的问题？我试着从现在开始调试2天，但没有运气。对不起，我的英语不好。谢谢！： - ）

class package.X使用非实体package.Y作为关系属性字段listOfQuestions中的目标实体

0 个答案: