(hibernate4) org.hibernate.MappingException: 未知实体

Question

我是Java EE的新手，请帮助！

以下代码使用struts2+hibernate4+oracle11g。运行此代码后，它给了我以下错误消息：

org.hibernate.MappingException: 未知实体

UserDetails.java

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

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

@Entity
@Table(name="users")
public class UserDetails {
    @Id
    private int id;
    private String passwd;
    public String getPasswd() {
        return passwd;
    }
    public void setPasswd(String passwd) {
        this.passwd = passwd;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }

    public void Update(){
        SessionFactory sessionFactory;
        ServiceRegistry serviceRegistry;

        Configuration configuration = new Configuration();
        configuration.configure();
        serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();        
        sessionFactory = configuration.buildSessionFactory(serviceRegistry);

        Session session = sessionFactory.openSession();
        session.beginTransaction();
        session.save(this);
        session.getTransaction().commit();
    }
}

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="dialect">org.hibernate.dialect.Oracle10gDialect</property>
    <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>
    <property name="connection.url">jdbc:oracle:thin:@192.168.1.2:1521:orcl</property>
    <property name="connection.username">steve</property>
    <property name="connection.password">steve</property>

    <property name="cache.provider_class">org.hibernate.cache.HashtableCacheProvider</property>

    <property name="transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property>
    <property name="current_session_context_class">thread</property>
    <property name="hibernate.show_sql">true</property>
    <property name="hbm2ddl.auto">create</property>
  </session-factory>

</hibernate-configuration>

表结构：

Create table Users (ID int primary key, passwd varchar(45));

Answer 1

问题是你还没有将你的类定义为hiberante。

在您的 session-factory 中添加以下几行：

<property name="annotatedClasses">
    <list>
        <value>myPackage.UserDetails</value>
    </list>
</property>

Answer 2

你需要添加类：

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

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

@Entity
@Table(name="users")
public class UserDetails {
    @Id
    private int id;
    private String passwd;
    public String getPasswd() {
        return passwd;
    }
    public void setPasswd(String passwd) {
        this.passwd = passwd;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }

    public void Update(){
        SessionFactory sessionFactory;
        ServiceRegistry serviceRegistry;

        Configuration configuration = new Configuration();
        configuration.addAnnotatedClass(UserDetails.class); //<-- Here, adds the class to the Hibernate configuration
        configuration.configure();
        serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();        
        sessionFactory = configuration.buildSessionFactory(serviceRegistry);

        Session session = sessionFactory.openSession();
        session.beginTransaction();
        session.save(this);
        session.getTransaction().commit();
    }
}

你肯定不想每次你想把东西保存到表中时都构造一个新的 Hibernate Configuration 和 SessionFactory，所以把东西从 Update 移到某个地方的 init 方法中。

Answer 3

缺少实体的休眠映射。或者，您可以在休眠配置文件中使用。 并定义 UserDetails.hbm.xml。我希望这会有所帮助。