与 OneToMany 和使用 hibernate 获取数据相关的错误

Question

正如你所看到的，我有两个类Person和Item，以及它们在数据库中的相应表，在App类中我试图使用hibernate使用一对多关系来获取一个人的所有东西。

人

package org.example;


import org.example.model.Item;
import org.example.model.Person;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

import java.time.Period;
import java.util.List;

public class App {
    public static void main(String[] args) {

        Configuration configuration = new Configuration()
                .addAnnotatedClass(Period.class).addAnnotatedClass(Item.class);

        SessionFactory sessionFactory = configuration.buildSessionFactory();
        Session session = sessionFactory.getCurrentSession();

        try {

            session.beginTransaction();

            Person person = session.get(Person.class, 1);
            System.out.println(person);

            List<Item> items = person.getItems();
            System.out.println(items);

            session.getTransaction().commit();
        } finally {
            sessionFactory.close();
        }
    }
}

项目

package org.example.model;


import jakarta.persistence.*;

@Entity
@Table(name = "item")
public class Item {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @Column(name = "item_name")
    String itemName;

    @ManyToOne
    @JoinColumn(name = "person_id", referencedColumnName = "id")
    private Person owner;

    public Item() {
    }

    public Item(String itemName) {
        this.itemName = itemName;
    }

    public int getId() {
        return id;
    }

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

    public String getItemName() {
        return itemName;
    }

    public void setItemName(String itemName) {
        this.itemName = itemName;
    }



    @Override
    public String toString() {
        return "Item{" +
                "id=" + id +
                ", itemName='" + itemName + '\'' +
                '}';
    }
}

应用程序

package org.example;


import org.example.model.Item;
import org.example.model.Person;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

import java.time.Period;
import java.util.List;

public class App {
    public static void main(String[] args) {

        Configuration configuration = new Configuration()
                .addAnnotatedClass(Period.class).addAnnotatedClass(Item.class);

        SessionFactory sessionFactory = configuration.buildSessionFactory();
        Session session = sessionFactory.getCurrentSession();

        try {

            session.beginTransaction();

            Person person = session.get(Person.class, 1);
            System.out.println(person);

            List<Item> items = person.getItems();
            System.out.println(items);

            session.getTransaction().commit();
        } finally {
            sessionFactory.close();
        }
    }
}

异常

Exception in thread "main" org.hibernate.AnnotationException: Association 'org.example.model.Item.owner' targets an unknown entity named 'org.example.model.Person'
    at org.hibernate.cfg.ToOneFkSecondPass.doSecondPass(ToOneFkSecondPass.java:97)
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processEndOfQueue(InFlightMetadataCollectorImpl.java:1879)
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processFkSecondPassesInOrder(InFlightMetadataCollectorImpl.java:1826)
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1733)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:300)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:97)
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:402)
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:90)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:735)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:773)
    at org.example.App.main(App.java:23)

1. 我尝试更改 pom.xml 中不同版本的依赖项以及 java 版本并重建项目
2. 尝试重新开课 3.我检查了数据库连接（它在那里是因为它通过@Colown注释中的名称消耗了到我需要的列的转换）

Answer 1

您在附加的 Person 类中犯了一个错误。您附加了一个应用程序类。