Explication détaillée du mappage de la collection Hibernate

Un mappage de liste

S'il existe un objet List dans la classe de persistance, la liste peut être mappée via l'élément de classe ou l'annotation dans le fichier de mappage.

Pour exemple, une question a plusieurs réponses :

1) Créer une classe de persistance

package list;

import java.util.List;

public class Question {
	
	private int id;
	
	private String qname;
	
	private List<String> answers;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getQname() {
		return qname;
	}

	public void setQname(String qname) {
		this.qname = qname;
	}

	public List<String> getAnswers() {
		return answers;
	}

	public void setAnswers(List<String> answers) {
		this.answers = answers;
	}
	
	

}

2) Créer un fichier de mappage

<?xml version=&#39;1.0&#39; encoding=&#39;UTF-8&#39;?>  
<!DOCTYPE hibernate-mapping PUBLIC  
 "-//Hibernate/Hibernate Mapping DTD 3.0//EN"  
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">  

 <hibernate-mapping>  
  <class name="list.Question" table="quesion">  
  	 <cache usage="read-write"/>
    <id name="id">  
     <generator class="increment"></generator>  
    </id>  
    <property name="qname"></property> 
    <list name="answers" table="answers">
    	<key column="qid"></key>
    	<index column="type"></index>
    	<element column="answer" type="string"></element>
    </list>
     
  </class>  

 </hibernate-mapping>

3) Ajouter

 	<!-- List of XML mapping files -->
   		<mapping resource="list/Question.hbm.xml"/>

au fichier de configuration global 4) Tester

package list;

import java.util.ArrayList;

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

public class Test {
	
	public static void main(String[] args) {
		
		Configuration cfg = new Configuration();
		cfg.configure("hibernate.cfg.xml");
		SessionFactory factory = cfg.buildSessionFactory();
		Session session = factory.openSession();
		session.beginTransaction();
		
		ArrayList<String> list1 = new ArrayList<String>();
		list1.add("answer1");
		list1.add("answer2");
		
		Question question1  = new Question();
		question1.setQname("question1");
		question1.setAnswers(list1);
		
		session.save(question1);
		
		session.getTransaction().commit();
		session.close();
		
		
		//factory.close();
		
		
	}

}

Mappage un-à-plusieurs à deux listes

Une question a plusieurs réponses, chaque réponse a sa propre information doit être cartographiée à l'aide d'une association un-à-plusieurs.

1) Créer une classe de persistance

package list;

import java.util.List;

public class Question {
	
	private int id;
	
	private String qname;
	
	private List<Answer> answers;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getQname() {
		return qname;
	}

	public void setQname(String qname) {
		this.qname = qname;
	}

	public List<Answer> getAnswers() {
		return answers;
	}

	public void setAnswers(List<Answer> answers) {
		this.answers = answers;
	}


	
	

}

package list;

public class Answer {
	
	private int id;
	
	private String answername;
	
	private String postedBy;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getAnswername() {
		return answername;
	}

	public void setAnswername(String answername) {
		this.answername = answername;
	}

	public String getPostedBy() {
		return postedBy;
	}

	public void setPostedBy(String postedBy) {
		this.postedBy = postedBy;
	}
	
	

}

2) Fichier de configuration

<?xml version=&#39;1.0&#39; encoding=&#39;UTF-8&#39;?>  
<!DOCTYPE hibernate-mapping PUBLIC  
 "-//Hibernate/Hibernate Mapping DTD 3.0//EN"  
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">  

 <hibernate-mapping>  
  <class name="list.Question" table="quesion">  
  	 <cache usage="read-write"/>
    <id name="id">  
     <generator class="increment"></generator>  
    </id>  
    <property name="qname"></property> 
    <list name="answers" cascade="all">
    	<key column="qid"></key>
    	<index column="type"></index>
    	<one-to-many class="list.Answer"/>
    </list>
   </class>
   
    <class name="list.Answer" table="answers">  
	  	 <cache usage="read-write"/>
	    <id name="id">  
	     <generator class="increment"></generator>  
	    </id>  
	    <property name="answername"></property> 
	    <property name="postedBy"></property>
    </class>  

 </hibernate-mapping>

3) Ajouter la configuration dans hibernate.cfg.xml

	 	<!-- List of XML mapping files -->
   		<mapping resource="list/Question.hbm.xml"/>

4) Tester

package list;

import java.util.ArrayList;

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

public class Test {
	
	public static void main(String[] args) {
		
		Configuration cfg = new Configuration();
		cfg.configure("hibernate.cfg.xml");
		SessionFactory factory = cfg.buildSessionFactory();
		Session session = factory.openSession();
		session.beginTransaction();
		
		Answer ans1 = new Answer();
		ans1.setAnswername("ans1");
		ans1.setPostedBy("post1");
		
		Answer ans2 = new Answer();
		ans2.setAnswername("ans2");
		ans2.setPostedBy("post2");
		
		Answer ans3 = new Answer();
		ans3.setAnswername("ans3");
		ans3.setPostedBy("post3");
		ArrayList<Answer> list1 = new ArrayList<Answer>();
		list1.add(ans1);
		list1.add(ans2);
		list1.add(ans3);
		Question question1  = new Question();
		question1.setQname("question1");
		question1.setAnswers(list1);
		session.save(question1);
		session.getTransaction().commit();
		session.close();
		//factory.close();
			
	}
}

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