Creating our Own Hibernate Template class

Let us see how to develop our own Hibernate Template class.

HibernateTemplate.java

import java.io.Serializable;
import java.util.List;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;

import com.varasofttech.util.HibernateUtil;

public class HibernateTemplate {
    private SessionFactory sessionFactory = null;
    
    public HibernateTemplate() {
        sessionFactory = HibernateUtil.getSessionFactory();
    }
    
    public Serializable save(Object entity) {
        Serializable id = null;
        Transaction transaction = null;
        Session session = sessionFactory.openSession();
        try {
            transaction = session.beginTransaction();
            id = session.save(entity);
            transaction.commit();
        } catch (RuntimeException e) {
            if (transaction != null) {
                transaction.rollback();
            }
            e.printStackTrace();
        } finally {
            session.flush();
            session.close();
        }
        return id;
    }
    
    public Object update(Object entity) {
        Transaction transaction = null;
        Session session = sessionFactory.openSession();
        try {
            transaction = session.beginTransaction();
            session.update(entity);
            transaction.commit();
        } catch (RuntimeException e) {
            if (transaction != null) {
                transaction.rollback();
            }
            e.printStackTrace();
        } finally {
            session.flush();
            session.close();
        }
        return entity;
    }
    
    public Object findById(Serializable id, Class<?> clas) {
        Session session = sessionFactory.openSession();
        return session.get(clas, id);
    }
    
    public void delete(Serializable id, Class<?> clas ) {
        Session session = sessionFactory.openSession();
        Transaction transaction = null;
        try {              
            transaction = session.beginTransaction();
            Object data = findById(id, clas); 
            session.delete(data);
            transaction.commit();
        } catch (HibernateException e) {
            transaction.rollback();
            e.printStackTrace();
        } finally {
            session.close();
        }
    }
    
    public List<?> findAll(Class<?> clas) {
        Session session = sessionFactory.openSession();
        Query query = session.createQuery( "from " + clas.getName());       
        return query.list();
    }
}

HibernateUtil.java

import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

public class HibernateUtil {
    private static final SessionFactory sessionFactory = buildSessionFactory();

    private static SessionFactory buildSessionFactory() {
        try {
            
            // Create the SessionFactory from hibernate.cfg.xml            
            Configuration configuration = new Configuration();
            configuration.configure("hibernate.cfg.xml"); 
            
            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                            .applySettings(configuration.getProperties())
                            .build();
            
            return configuration.buildSessionFactory(serviceRegistry); 
            
        } catch (Throwable ex) {
            // Make sure you log the exception, as it might be swallowed
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }
    
    public static void closeSessionFactory() {
        if(sessionFactory != null) {
            sessionFactory.close();
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}