Hibernate Many to Many Annotation Mapping

Relationship Diagram

Project Structure

  

File Name	Use
Language.java	Pojo class with mapping for Language.
Person.java	Pojo class with mapping for Person.
hibernate.cfg.xml	Hibernate Configuration File.
Main.java	It will control the overall process.

Language.java

package manyToMany.annotation;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.Table;

@Entity

@Table(name="LANGUAGE")

public class Language 

{

@Id

@Column(name = "LANGUAGE_ID")

@GeneratedValue

private long langId;

@Column(name = "LANGUAGE_NAME")

private String langName;

public Language() { }  //no argument constructor 

public Language(String langName) {

this.langName = langName;

} 

public long getLangId() {

return langId;

}

public void setLangId(long langId) {

this.langId = langId;

}

public String getLangName() {

return langName;

}

public void setLangName(String langName) {

this.langName = langName;

}

}

Person.java

package manyToMany.annotation;

import java.util.HashSet;

import java.util.Set;

import javax.persistence.CascadeType;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.ManyToMany;

import javax.persistence.Table;

import javax.persistence.JoinColumn;

import javax.persistence.JoinTable;

@Entity

@Table(name="PERSON")

public class Person 

{

@Id

@Column(name = "PERSON_ID")

@GeneratedValue

private long personId;

@Column(name = "PERSON_NAME")

private String personName;

@ManyToMany(cascade = {CascadeType.ALL})

@JoinTable(name = "PERSON_LANGUAGE",

  joinColumns = {@JoinColumn(name="PERSON_ID")},

  inverseJoinColumns={@JoinColumn(name="LANGUAGE_ID")})

private Set<Language> languages = new HashSet<Language>(0);

public Person() {}  //no argument constructor

public long getPersonId() {

return personId;

}

public void setPersonId(long personId) {

this.personId = personId;

}

public String getPersonName() {

return personName;

}

public void setPersonName(String personName) {

this.personName = personName;

}

public Set<Language> getLanguages() {

return languages;

}

public void setLanguages(Set<Language> languages) {

this.languages = languages;

}

}

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="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>

<property name="hibernate.connection.url">jdbc:mysql://localhost/mydb</property> 

<property name="hibernate.connection.username">root</property>

<property name="connection.password">root</property>

<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

<property name="hibernate.hbm2ddl.auto">create</property>

<property name="show_sql">true</property> 

        <mapping class="manyToMany.annotation.Person"/>

        <mapping class="manyToMany.annotation.Language"/>

    </session-factory>

</hibernate-configuration>

Main.java

package manyToMany.simple;

import java.util.HashSet;

import java.util.Set;

import org.hibernate.HibernateException;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.cfg.Configuration;

public class Main 

{

          public static void main(String[] args) 

          {

                   Configuration config = new Configuration().configure("manyToMany\\simple\\hibernate.cfg.xml");

                   SessionFactory myFactory = config.buildSessionFactory(); 

                   Session session = myFactory.openSession();

                   Transaction transaction = null;

                   try {

                             transaction = session.beginTransaction();

                             Set<Language> languages = new HashSet<Language>();

                             languages.add(new Language("English"));

                             languages.add(new Language("Hindi"));

                             Person person = new Person();

                             person.setPersonName("Hemant Kumar");

                             person.setLanguages(languages);

                             session.save(person);

                             transaction.commit();

                   } 

                   catch(HibernateException e) {

                             transaction.rollback();

                             e.printStackTrace();

                   } 

                   finally {

                             session.close();

                   }

          }

}