Exception in thread "main" org.hibernate.MappingException: Unknown entity:

Question

I'm using myeclipse IDE After executing my code i'm getting the below Exception

log4j:WARN No appenders could be found for logger 

(org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.hibernate.MappingException: Unknown entity:info.inetsolv.Emp
at org.hibernate.impl.SessionFactoryImpl.getEntityPersister

(SessionFactoryImpl.java:628)
at org.hibernate.impl.SessionImpl.getEntityPersister

(SessionImpl.java:1366)
at org.hibernate.engine.ForeignKeys.isTransient(ForeignKeys.java:203)
at org.hibernate.event.def.AbstractSaveEventListener.getEntityState

(AbstractSaveEventListener.java:535)
at org.hibernate.event.def.DefaultPersistEventListener.onPersist

(DefaultPersistEventListener.java:93)
at org.hibernate.event.def.DefaultPersistEventListener.onPersist

(DefaultPersistEventListener.java:61)
at org.hibernate.impl.SessionImpl.firePersist(SessionImpl.java:646)
at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:620)
at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:624)
at info.inetsolv.InsertEmprecord.main(InsertEmprecord.java:22)

POJO CLASS

---

package info.inetsolv;
@SuppressWarnings("serial")
public class Emp implements java.io.Serializable {

// Fields

private Integer eno;
private String name;
private Double salary;

// Constructors

/** default constructor */
public Emp() {
}

/** minimal constructor */
public Emp(Integer eno) {
    this.eno = eno;
}

/** full constructor */
public Emp(Integer eno, String name, Double salary) {
    this.eno = eno;
    this.name = name;
    this.salary = salary;
}

// Property accessors

public Integer getEno() {
    return this.eno;
}

public void setEno(Integer eno) {
    this.eno = eno;
}

public String getName() {
    return this.name;
}

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

public Double getSalary() {
    return this.salary;
}

public void setSalary(Double salary) {
    this.salary = salary;
}

}

HibernateSessionFactory.java

---

package info.inetsolv;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
 public class HibernateSessionFactory {

private static final ThreadLocal<Session> threadLocal = new 

ThreadLocal<Session>();
private static org.hibernate.SessionFactory sessionFactory;

private static Configuration configuration = new Configuration();
private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
private static String configFile = CONFIG_FILE_LOCATION;

static {
    try {
        configuration.configure(configFile);
sessionFactory = configuration.buildSessionFactory();
    } catch (Exception e) {
System.err.println("%%%% Error Creating SessionFactory %%%%");
        e.printStackTrace();
    }
}
private HibernateSessionFactory() {
}

public static Session getSession() throws HibernateException {
    Session session = (Session) threadLocal.get();

    if (session == null || !session.isOpen()) {
        if (sessionFactory == null) {
            rebuildSessionFactory();
        }
    session = (sessionFactory != null) ? sessionFactory.openSession(): null;
        threadLocal.set(session);
    }

    return session;
}

public static void rebuildSessionFactory() {
try {
configuration.configure(configFile);
sessionFactory = configuration.buildSessionFactory();
    } catch (Exception e) {
System.err.println("%%%% Error Creating SessionFactory %%%%");
        e.printStackTrace();
    }
}

public static void closeSession() throws HibernateException {
    Session session = (Session) threadLocal.get();
    threadLocal.set(null);

    if (session != null) {
        session.close();
    }
}

public static org.hibernate.SessionFactory getSessionFactory() {
    return sessionFactory;
}

public static void setConfigFile(String configFile) {
    HibernateSessionFactory.configFile = configFile;
    sessionFactory = null;
}
public static Configuration getConfiguration() {
    return configuration;
}

}

client program to insert record into DB

InsertEmprecord.java

package info.inetsolv;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

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

Configuration cfg = new Configuration();
cfg.configure();
SessionFactory sf = cfg.buildSessionFactory();
Session hsession = sf.openSession();
Transaction tx = hsession.beginTransaction();

Emp e = new Emp();
e.setEno(6);
e.setName("six");
e.setSalary(1234d);
hsession.persist(e);

tx.commit();
hsession.close();
sf.close();


}

}

And below is my hibernate mapping file Emp.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 

3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
<class name="info.inetsolv.Emp" table="EMP" schema="HIB">
    <id name="eno" type="java.lang.Integer">
        <column name="ENO" precision="5" scale="0" />
        <generator class="assigned" />
    </id>
    <property name="name" type="java.lang.String">
        <column name="NAME" length="10" />
    </property>
    <property name="salary" type="java.lang.Double">
        <column name="SALARY" precision="10" />
    </property>
</class>
</hibernate-mapping>

AND below is my hibernate configuration file

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">
<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>

<session-factory>
<property name="dialect">
    org.hibernate.dialect.Oracle9Dialect
</property>
<property name="connection.url">
    jdbc:oracle:thin:@localhost:1521:xe
</property>
<property name="connection.username">hib</property>
<property name="connection.password">abc</property>
<property name="connection.driver_class">
    oracle.jdbc.driver.OracleDriver
</property>
<property name="myeclipse.connection.profile">
    my oracle drive
</property>
<property name="show_sql">true</property>

</session-factory>

</hibernate-configuration>

Answer 1

@Sandhu Santakumar , answer is absolutely right.

Just adding the reason behind this. By default the JBoss hibernate reverse engineering tool maps class inside the mapping tab but resource attribute is the required attribute that hibernate.cfg.xml should have. class attribute is optional.

e.g. if your mapping is like this

resource is mandatory attribute and class is optional attribute.

Hope this additional information helps.

Answer 2

I had similar problem for a simple Console application trying to use Hibernate. The solution I arrived to make the add the "packagesToScan" property explicitly for LocalSessionFactoryBean.

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
   <property name="dataSource" ref="dataSource"/>
   <property name="packagesToScan" value="com.mg.learning.spring.orm"/> <--- this SOLVED!
   <property name="hibernateProperties">
    <props>
        <prop key="dialect">org.hibernate.dialect.MySQL5Dialect</prop>
        <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
    </props>
   </property>
</bean>

Answer 3

You didn't configure mapping for the object Emp. The configuration file hibernate.cfg.xml should contain the mapping to the resource Emp.hbm.xml.

<mapping resource="info/inetsolv/Emp.hbm.xml"/>