主页 / 问题 / 847064
Accepted
YuriiS
Asked:2020-06-27 01:01:46 +0000 UTC2020-06-27 01:01:46 +0000 UTC

尝试从数据库中删除时未在休眠中定义的实体

  • 772

我无法弄清楚为什么Exception in thread "main" java.lang.IllegalArgumentException: Unknown entity: java.lang.Long在运行 delete 方法时会发生错误(Long id)。这些方法save(Item item), update(Item item) and findById(Long id可以正常工作。请告诉我可能出了什么问题。类Item：

import javax.persistence.*;
import java.util.Date;

@Entity
@Table(name = "ITEM")
public class Item {
    private Long id;
    private String name;
    private Date dateCreated;
    private Date lastUpdateDate;
    private String description;

    public Item() {
    }

    public Item(String name, Date dateCreated, Date lastUpdateDate, String description) {
        this.name = name;
        this.dateCreated = dateCreated;
        this.lastUpdateDate = lastUpdateDate;
        this.description = description;
    }

    @Id
    @SequenceGenerator(name = "IT_SQ", sequenceName = "ITEM_SEQ", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "IT_SQ")
    public Long getId() {
        return id;
    }

    @Column(name = "NAME")
    public String getName() {
        return name;
    }

    @Column(name = "DATE_CREATED")
    public Date getDateCreated() {
        return dateCreated;
    }

    @Column(name = "LAST_UPDATE_DATE")
    public Date getLastUpdateDate() {
        return lastUpdateDate;
    }

    @Column(name = "DESCRIPTION")
    public String getDescription() {
        return description;
    }

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

    public void setName(String name) {
        this.name = name;
    }

    public void setDateCreated(Date dateCreated) {
        this.dateCreated = dateCreated;
    }

    public void setLastUpdateDate(Date lastUpdateDate) {
        this.lastUpdateDate = lastUpdateDate;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    @Override
    public String toString() {
        return "Item{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", dateCreated=" + dateCreated +
                ", lastUpdateDate=" + lastUpdateDate +
                ", description='" + description + '\'' +
                '}';
    }
}

类ItemDAO：

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.query.NativeQuery;

public class ItemDAO {

    private static SessionFactory sessionFactory;

    private static final String SQL_GET_ITEM_BY_ID = "SELECT * FROM ITEM WHERE ID = ?";

    public Item save(Item item){

        Transaction transaction = null;
        try(Session session = createSessionFactory().openSession()) {
            transaction = session.getTransaction();
            transaction.begin();

            session.save(item);

            transaction.commit();
            System.out.println("Saved successfully");
        }catch (HibernateException e){
            System.err.println("Saved is failed");
            System.err.println(e.getMessage());
            if (transaction != null)
                transaction.rollback();
        }
        return item;
    }

    public void update(Item item){

        Transaction transaction = null;
        try (Session session = createSessionFactory().openSession()){
            transaction = session.getTransaction();
            transaction.begin();

            session.update(item);

            System.out.println("Update was successful");

            transaction.commit();
        }catch (HibernateException e){
            System.err.println("Save is failed");
            System.err.println(e.getMessage());
            if (transaction != null)
                transaction.rollback();
        }
    }

    public void delete(Long id){

        Transaction transaction = null;
        try (Session session = createSessionFactory().openSession()){
            transaction = session.getTransaction();
            transaction.begin();

            session.delete(id);

            System.out.println("Recording deleted successfully");

            transaction.commit();
        }catch (HibernateException e){
            System.err.println("Save is failed");
            System.err.println(e.getMessage());
            if (transaction != null)
                transaction.rollback();
        }
    }

    @SuppressWarnings("unchecked")
    public Item findById(Long id){

        Item item;

        try (Session session = createSessionFactory().openSession()){

            NativeQuery query = session.createNativeQuery(SQL_GET_ITEM_BY_ID);
            item = (Item) query.addEntity(Item.class).setParameter(1, id).getSingleResult();

        }catch (HibernateException e){
            System.err.println("Save is failed");
            System.err.println(e.getMessage());
            throw e;
        }
        System.out.println("Save is done");

        return item;
    }

    private static SessionFactory createSessionFactory(){
        if (sessionFactory == null){
            sessionFactory = new Configuration().configure().buildSessionFactory();
        }
        return sessionFactory;
    }
}

Pom file：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>crud-servlet</groupId>
    <artifactId>crud-servlet</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.0-b07</version>
            <!--<scope>provided</scope>-->
        </dependency>

        <dependency>
            <groupId>com.oracle</groupId>
            <artifactId>ojdbc7</artifactId>
            <version>12.1.0</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.2.16.Final</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.6.3</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

文件hibernate.cfg.xml：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="hibernate.connection.url">jdbc:oracle:thin:@gromcode-lesson.cjqbbseqr63c.eu-central-1.rds.amazonaws.com:1521:ORCL</property>
        <property name="hibernate.connection.username">main</property>
        <property name="hibernate.connection.password">ifgjrkzr</property>

        <property name="show_sql">true</property>
        <mapping class="Item"></mapping>
    </session-factory>

    <!--<open_tag params>value</open_tag>-->
</hibernate-configuration>

实际的堆栈跟踪有错误：

    июн 26, 2018 7:35:33 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {5.2.16.Final}
июн 26, 2018 7:35:33 PM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
июн 26, 2018 7:35:33 PM org.hibernate.boot.jaxb.internal.stax.LocalXmlResourceResolver resolveEntity
WARN: HHH90000012: Recognized obsolete hibernate namespace http://hibernate.sourceforge.net/hibernate-configuration. Use namespace http://www.hibernate.org/dtd/hibernate-configuration instead.  Support for obsolete DTD/XSD namespaces may be removed at any time.
июн 26, 2018 7:35:34 PM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
WARN: HHH10001002: Using Hibernate built-in connection pool (not for production use!)
июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001005: using driver [oracle.jdbc.driver.OracleDriver] at URL [jdbc:oracle:thin:@gromcode-lesson.cjqbbseqr63c.eu-central-1.rds.amazonaws.com:1521:ORCL]
июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001001: Connection properties: {user=main, password=****}
июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001003: Autocommit mode: false
июн 26, 2018 7:35:34 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections <init>
INFO: HHH000115: Hibernate connection pool size: 20 (min=1)
июн 26, 2018 7:35:35 PM org.hibernate.dialect.Dialect <init>
INFO: HHH000400: Using dialect: org.hibernate.dialect.Oracle10gDialect
Exception in thread "main" java.lang.IllegalArgumentException: Unknown entity: java.lang.Long
    at org.hibernate.internal.SessionImpl.fireDelete(SessionImpl.java:1000)
    at org.hibernate.internal.SessionImpl.delete(SessionImpl.java:929)
    at ItemDAO.delete(ItemDAO.java:61)
    at Demo.main(Demo.java:23)
Caused by: org.hibernate.MappingException: Unknown entity: java.lang.Long
    at org.hibernate.metamodel.internal.MetamodelImpl.entityPersister(MetamodelImpl.java:620)
    at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1635)
    at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:82)
    at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:56)
    at org.hibernate.internal.SessionImpl.fireDelete(SessionImpl.java:993)
    ... 3 more

Process finished with exit code -1

一切似乎都是正确的，但某处缺少某些东西......

java

1 个回答

  1. Best Answer
    session.delete(findById(id));

    您需要将 Item 实体传递给方法delete

    • 1

相关问题