Many to Many XML

Creating the Mapping file in Many to Many XML

In the below implementation, we will be creating files named questions.hbm.xml and answers.hbm.xml for defining the list.

questions.hbm.xml

<?xml version='1.0' encoding='UTF-8'?>    
<!DOCTYPE hibernate-mapping PUBLIC    
          "-//Hibernate/Hibernate Mapping DTD 5.3//EN"    
          "http://hibernate.sourceforge.net/hibernate-mapping-5.3.dtd">    
              
<hibernate-mapping>    
  
  <class name="com.codingninjas.Question" table="questions_1">  
        <id name="id" type="int">  
            <column name="qid" />  
            <generator class="increment" />  
        </id>  
        <property name="qname" />  
  
        <list name="answers" table="ques_ans_1" fetch="select" cascade="all">  
            <key column="qid" />  
               <index column="type"></index>   
            <many-to-many class="com.codingninjas.Answer" column="ans_id" />  
        </list>  
    </class>   
</hibernate-mapping>     

answers.hbm.xml

<?xml version='1.0' encoding='UTF-8'?>    
<!DOCTYPE hibernate-mapping PUBLIC    
          "-//Hibernate/Hibernate Mapping DTD 5.3//EN"    
          "http://hibernate.sourceforge.net/hibernate-mapping-5.3.dtd">    
              
<hibernate-mapping>    
<class name="com.codingninjas.Answer" table="answers_1">  
        <id name="id" type="int">  
            <column name="ans_id" />  
            <generator class="increment" />  
        </id>  
        <property name="answername"  />  
        <property name="postedBy" />  
    </class>  
</hibernate-mapping>

Configuration File in Many to Many XML

This file provides database and mapping file information.

hibernate.cfg.xml

<?xml version='1.0' encoding='UTF-8'?>    
<!DOCTYPE hibernate-configuration PUBLIC    
          "-//Hibernate/Hibernate Configuration DTD 5.3//EN"    
          "http://hibernate.sourceforge.net/hibernate-configuration-5.3.dtd">    
    
<hibernate-configuration>    
    
    <session-factory>    
        <property name="hbm2ddl.auto">create</property>    
        <property name="dialect">org.hibernate.dialect.Oracle9Dialect</property>    
        <property name="connection.url">jdbc:oracle:thin:@localhost:1521:xe</property>    
        <property name="connection.username">system</property>    
        <property name="connection.password">jtp</property>    
        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>    
    <mapping resource="question.hbm.xml"/>    
    <mapping resource="answer.hbm.xml"/>  
    </session-factory>    
    
</hibernate-configuration>

Classes to Store the Data in Many to Many XML

We define a user class named store.java to store the data in many-to-many mapping using XML respectively.

StoreData.java

The data from the question class is stored in this class.

package com.codingninjas;    
  
import java.util.ArrayList;    
    
import org.hibernate.SessionFactory;  
import org.hibernate.Session;
import org.hibernate.Transaction;  
import org.hibernate.boot.MetadataSources;  
import org.hibernate.boot.Metadata;  
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;  
import org.hibernate.boot.registry.StandardServiceRegistry;  


public class StoreData 
{    
	public static void main(String[] args) 
	{    
     
    	StandardServiceRegistry ssr=new StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build();  
    	Metadata meta=new MetadataSources(ssr).getMetadataBuilder().build();  
      
    	SessionFactory factory=meta.getSessionFactoryBuilder().build();  
    	Session session=factory.openSession();  
      
    	Transaction t=session.beginTransaction();    
        
    	Answer ans1=new Answer();    
    	ans1.setAnswername("Orange is a color");    
    	ans1.setPostedBy("Coder1");    
        
    	Answer ans2=new Answer();    
    	ans2.setAnswername("Orange is a fruit");    
   		ans2.setPostedBy("Coder2");    
        
    	Answer ans3=new Answer();    
    	ans3.setAnswername("Averse is a noun");    
    	ans3.setPostedBy("Coder3");    
        
    	Answer ans4=new Answer();    
    	ans4.setAnswername("Averse is an adjective");    
    	ans4.setPostedBy("Coder4");    
        
    	ArrayList<Answer> list1=new ArrayList<Answer>();    
    	list1.add(ans1);    
    	list1.add(ans2);    
        
    	ArrayList<Answer> list2=new ArrayList<Answer>();    
    	list2.add(ans3);    
    	list2.add(ans4);    
        
    	Question question1=new Question();    
    	question1.setQname("What is Orange?");    
    	question1.setAnswers(list1);    
        
    	Question question2=new Question();    
    	question2.setQname("What is averse?");    
    	question2.setAnswers(list2);    
        
    	session.persist(question1);    
    	session.persist(question2);    
        
    	t.commit();    
    	session.close();    
    	System.out.println("Done");    
    }    
}   

You can also try this code with Online Java Compiler

Run Code

Output

Frequently Asked Questions

What is hibernate?

A lightweight, open-source ORM tool called Hibernate is used to store, alter, and retrieve data from databases.

What is a ClassLoader?

A classloader is a part of Java Virtual Machine that loads class files when a program is run in Java. The first executable file to load is ClassLoader.

What is ORM?

The term "ORM" stands for "Object/Relational Mapping." The mapping of objects to the data kept in the database is a programming technique. It makes data access, data manipulation, and data generation easier.

Conclusion

In this article, we have extensively discussed the Many to Many XML in hibernate using, its example, and file mapping in hibernate project structure.

If you find this blog has improved your understanding of Many to Many XML and if you would like to learn more, check out our articles Hibernate Interview Questions, OOPS in Java, Java Framework, and JDBC Connection.

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