实体没有映射- hibernate

Question

我试图用hibernate创建一个小项目，但我得到了错误"类型不映射[select o from Type o]"，我在hibernate.cfg.xml中添加了映射，但仍然错误。

Type.java:

package com.formation.gestionprojet.doa.entity;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="Type")
public class Type implements Serializable {
/**
 * 
 */
private static final long serialVersionUID = 1L;
@Id
private Long id;
private String name;
private String description;
private String active;


public Type() {
    super();
    // TODO Auto-generated constructor stub
}
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public String getDescription() {
    return description;
}
public void setDescription(String description) {
    this.description = description;
}
public String getActive() {
    return active;
}
public void setActive(String active) {
    this.active = active;
}   
}

hibernate.org.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>
<!--  database connection setting -->
<property name ="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/gestion_projet?createDatabaseIfNotExist=true</property>
<property name="connection.username">root</property>
<property name= "connection.password">root</property>
<!-- Dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Disable the second level cache -->
<property name="cache.provider_class" >org.hibernate.cache.NoCacheProvider</property>
<!-- echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Drope and re-create the database -->
<property name="hbm2ddl.auto">update</property>
<!-- mapping -->

<mapping class= "com.formation.gestionprojet.doa.entity.Type"/>

</session-factory>
</hibernate-configuration>

hibernateUtil.java:

package com.formation.gestionprojet.utils;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
@SuppressWarnings("deprecation")
public class HibernateUtil
{
    private static SessionFactory sessionFactory;
    private static ServiceRegistry serviceRegistry;
    static
    {
        try
        {
            Configuration configuration = new Configuration();
            configuration.configure("config/hibernate.cfg.xml");
            serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
            sessionFactory = configuration.buildSessionFactory(serviceRegistry);
        }
        catch (HibernateException ex)
        {
            System.err.println("Error creating Session: " + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }
    public static SessionFactory getSessionFactory()
    {
        return sessionFactory;
    } 

    public static Session openSession()
    {
        return sessionFactory.openSession();
    } 

    public static Session getCurrentSession()
    {
        return sessionFactory.getCurrentSession();
    } 

    public static void close(){
        if(sessionFactory!=null){
            sessionFactory.close();
        }
    }

}

Test.Java

package com.formation.gestionprojet.utils;
import org.hibernate.Session;

public class Test {
    static Session session = HibernateUtil.openSession();
    public static void main(String[] args) {
        session.createQuery("select o from Type o").list();

    }
}

Answer 1

首先，Type是JPA/Hibernate API的一部分。所以考虑重命名它，例如MyType或类似的东西。

其次，select在HQL中不是强制的。因此，您可以简单地使用FROM子句来设置所有内容。

第三，尝试在查询中使用类的全限定名。

"FROM com.formation.gestionprojet.doa.entity.MyType"