Example of @OneToOne in Hibernate
May 20, 2013
The meaning of one-to-one is that one table will be associated with another table by single value. In the example we suppose that a country can have one president and we did one-to-one mapping. Syntax will look like
@OneToOne(cascade = CascadeType.ALL) @PrimaryKeyJoinColumn
Country.java
package com.concretepage.persistence;
import java.io.Serializable;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
@Entity
public class Country implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@Column(name="id")
private int id;
@Column(name="name")
private String name;
@OneToOne(cascade = CascadeType.ALL)
@PrimaryKeyJoinColumn
private President president;
public Country (int id, String name,President president){
this.id=id;
this.name=name;
this.president=president;
}
public Country (){}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public President getPresident() {
return president;
}
public void setPresident(President president) {
this.president = president;
}
}
President.java
package com.concretepage.persistence;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "president")
public class President {
@Id
@Column(name = "id")
private int id;
@Column(name = "name")
private String name;
public President(){ }
public President(int id, String name){
this.id=id;
this.name=name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
HibernateUtil.java
package com.concretepage.util;
import java.util.Properties;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import com.concretepage.persistence.Country;
import com.concretepage.persistence.President;
public class HibernateUtil {
private static final SessionFactory concreteSessionFactory;
static {
try {
Properties prop= new Properties();
prop.setProperty("hibernate.connection.url", "jdbc:mysql://localhost:3306/hibernate");
prop.setProperty("hibernate.connection.username", "root");
prop.setProperty("hibernate.connection.password", "");
prop.setProperty("hibernate.hbm2ddl.auto", "update");
prop.setProperty("show_sql", "true");
prop.setProperty("dialect", "org.hibernate.dialect.MySQLDialect");
concreteSessionFactory = new AnnotationConfiguration()
.addPackage("com.concretepage.persistence")
.addProperties(prop)
.addAnnotatedClass(Country.class)
.addAnnotatedClass(President.class)
.buildSessionFactory();
} catch (Throwable ex) {
throw new ExceptionInInitializerError(ex);
}
}
public static Session getSession()
throws HibernateException {
return concreteSessionFactory.openSession();
}
public static void main(String... args){
Session session=getSession();
session.beginTransaction();
President p= new President(1,"ABC");
Country country= new Country(1,"India",p);
session.save(country);
session.getTransaction().commit();
}
}
