In this paper we will try to write a mavenized java application that will connect to an Oracle database and perform some data manipulation.
First of all, why maven ?
If you have the right jar dependencies whithout maven that's great ! no need to use maven... Personally i've faced a big problem to download and put the correct dependencies (no only packages but versions also!) together into my project.
Then let's talk maven !
1- Create the application with maven
Run this command line :
mvn archetype:generate -DgroupId=com.itillusion.migrators -DartifactId=loader -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false
2- Add dependencies to POM
org.hibernate
hibernate-core
5.2.11.Final
org.hibernate
hibernate-tools
3.2.0.ga
And that's all, no need to other dependencies ...
So our new pom.xml become :
4.0.0
com.itillusion.migrators
loader
jar
1.0-SNAPSHOT
loader
http://maven.apache.org
junit
junit
3.8.1
test
org.hibernate
hibernate-core
5.2.11.Final
org.hibernate
hibernate-tools
3.2.0.ga
Note that here we use hibernate 5.2.11
3- Build the HibernateUtils class
This class is recommended, it is a Singleton design pattern implementation, and will facilitate our work
package com.itillusion.migrators.utils;
import java.util.ArrayList;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import tn.cnss.referentiel.models.Assure;
import tn.cnss.referentiel.models.Beneficiaire;
public class HibernateUtils {
private static final SessionFactory sessionFactory;
static {
try {
StandardServiceRegistry standardRegistry =
new StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build();
//Annotated classes to be scanned
List> classes = new ArrayList>();
classes.add(Assure.class);
classes.add(Beneficiaire.class);
//Attach classes
MetadataSources metadataSources = new MetadataSources(standardRegistry);
for (Class annotatedClass : classes) {
metadataSources.addAnnotatedClass(annotatedClass);
}
sessionFactory = metadataSources.buildMetadata()
.buildSessionFactory();
} catch (Throwable th) {
System.err.println("Enitial SessionFactory creation failed" + th);
throw new ExceptionInInitializerError(th);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
public static Session getSession() throws org.hibernate.HibernateException {
SessionFactory sessionFactory = HibernateUtils.getSessionFactory();
Session sess = null;
try {
sess = sessionFactory.getCurrentSession();
} catch (org.hibernate.HibernateException he) {
sess = sessionFactory.openSession();
}
return sess;
}
}
Note in the fragment
classes.add(Assure.class);
classes.add(Beneficiaire.class);
We have added our annotated classes !
I'm sure that there is a more elegant methods to do this, (iteration on packages using java reflection api) but in my case i just need two tabled to map.
Note also that we conserved our classic hibernate.cfg.xml file. (Surely we can avoid that and use100% java code to confgiure hibernate, but i don't recommand that and it is more logic to store database informations in a separate faile that can change independently from our code)
Here is a simple cfg file:
oracle.jdbc.driver.OracleDriver
PASSWORD
jdbc:oracle:thin:@xxx.yy.zz.tt:SID
USERNAME
DEFAULT_SCHEMA
org.hibernate.dialect.Oracle10gDialect
to be continued