I am new to Hibernate. While creating a small app using it I got following exception:
Exception in thread “main” java.lang.IllegalArgumentException: Unknown entity:
model.Students at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:223)
at controller.Main.main(Main.java:50)
Can anybody please help me out?
The Entity classes are as follows:
Other details:
NetBeans Version: 6.7.1
Hibernate : 3.2.5
Entity Students
package model;
import java.io.Serializable;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
@Entity
public class Students implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
@OneToOne(cascade=CascadeType.ALL)
private Address address;
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
}
Another Entity Class
package model;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
public class Address implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String city;
private String zip;
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getZip() {
return zip;
}
public void setZip(String zip) {
this.zip = zip;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
}
The DAO file
package controller; import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import model.Address;
import model.Students;
import org.hibernate.HibernateException;
public class Main {
public static void main(String arr[])
{
EntityManagerFactory emf = Persistence.createEntityManagerFactory("OneToOne2PU");
EntityManager em = emf.createEntityManager();
EntityTransaction tr= em.getTransaction();
try{
tr.begin();
Address add1 = new Address();
add1.setCity("pune");
add1.setZip("09");
Address add2 = new Address();
add2.setCity("mumbai");
add2.setZip("12");
Students s1 = new Students();
s1.setName("abc");
s1.setAddress(add1);
Students s2 = new Students();
s2.setName("xyz");
s2.setAddress(add2);
em.persist(s1);
em.persist(s2);
tr.commit();
emf.close();
}
catch(HibernateException e){
e.printStackTrace();
}
}
}
The persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="OneToOnePU" transaction-type="JTA">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<jta-data-source>students</jta-data-source>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="hibernate.hbm2ddl.auto" value="create-tables"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.DerbyDialect"/>
<property name="hibernate.connection.username" value="app"/>
<property name="hibernate.connection.password" value="app"/>
<property name="hibernate.connection.url" value="jdbc:derby://localhost:1527/StudentsData"/>
</properties>
</persistence-unit>
</persistence>
The hibernate.cfg.xml file
<?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.dialect">org.hibernate.dialect.DerbyDialect</property>
<property name="hibernate.connection.driver_class">org.apache.derby.jdbc.ClientDriver</property>
<property name="hibernate.connection.url">jdbc:derby://localhost:1527/sample</property>
<property name="hibernate.connection.username">app</property>
<property name="hibernate.connection.password">app</property>
<mapping class="model.Students"/>
<mapping class="model.Address"/>
</session-factory>
</hibernate-configuration>
Depends bit about project structure, but likely by adding following to persistence.xml directly under persistence-unit element.
Exactly like this:
By the way, why do you configure properties like hibernate.dialect in both persistence.xml and hibernate.cfg.xml?