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Should session and factory be closed?

I'm using Hibernate 5.0.2.Final with a Data-Source connection (On a Tomcat 8.0.15) and started to ask myself if it's necessary to not only close the Session but also the SessionFactory?
Right now it looks like this:
public static List<HibernateList> getHibernateList() {
Session session = null;
final String hql = "SELECT H FROM myhibernate.MyHibernate";
try {
SessionFactory factory = HibernateUtil.getSessionFactory();
session = factory.openSession();
session.beginTransaction();
Query query = session.createQuery(hql);
return query.list();
} catch (HibernateException hibex) {
Logger.getLogger(Hibernatepicker.class.getName()).log(Level.INFO, null, hql);
Logger.getLogger(Hibernatepicker.class.getName()).log(Level.SEVERE, null, hibex);
} finally {
try {
if (session != null) {
session.close();
}
} catch (HibernateException hibex) {
}//Nothing I could do...
}
return null;
}
Some details from the hibernate.cfg.xml
<property name="hibernate.connection.datasource">java:comp/env/jdbc/sqlserv</property>
<property name="current_session_context_class">thread</property>
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<property name="hbm2ddl.auto">auto</property>
<property name="show_sql">false</property>
<property name="hibernate.generate_statistics">true</property>
And the HibernateUtil:
public class HibernateUtil {
private static final SessionFactory sessionFactory;
static {
try {
Configuration cfg = new Configuration();
sessionFactory = cfg.configure("hibernate.cfg.xml").buildSessionFactory();
} catch (Throwable ex) {
Logger.getLogger(HibernateUtil.class.getName()).log(Level.SEVERE, null, ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}
I'm undecided whether it's necessary or not to call this method in the finally-block instead of only closing the session:
public static void disconnect(Session session, SessionFactory factory) {
try {
if (session != null) {
session.close();
} else {
Logger.getLogger(HibernateUtil.class.getName()).log(Level.INFO, null, "Session is Null");
}
} catch (HibernateException | NullPointerException hibex) {
Logger.getLogger(HibernateUtil.class.getName()).log(Level.INFO, null, "Couldn't close session, but there's nothing we can do...");
Logger.getLogger(HibernateUtil.class.getName()).log(Level.SEVERE, null, hibex);
}
try {
if (factory != null) {
factory.close();
} else {
Logger.getLogger(HibernateUtil.class.getName()).log(Level.INFO, null, "Factory is Null");
}
} catch (HibernateException | NullPointerException hibex) {
Logger.getLogger(HibernateUtil.class.getName()).log(Level.INFO, null, "Couldn't close session, but there's nothing we can do...");
Logger.getLogger(HibernateUtil.class.getName()).log(Level.SEVERE, null, hibex);
}
}

You should not close your SessionFactory on every query. Your SessionFactory should be initialised only once per application.
From the hibernate documentation.
The main contract here is the creation of Session instances. Usually
an application has a single SessionFactory instance and threads
servicing client requests obtain Session instances from this factory.
The internal state of a SessionFactory is immutable. Once it is
created this internal state is set. This internal state includes all
of the metadata about Object/Relational Mapping.
Implementors must be threadsafe.

java hibernate tomcat configuration - Session will not be opened

I am trying to configure hibernate and tomcat, so that tomcat will manage the database conections, but I am getting some errors.
Could you help? Here is my code:
Here is the HibernateUtil
public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();
private static SessionFactory buildSessionFactory() {
try {
// Create the SessionFactory from hibernate.cfg.xml
return new AnnotationConfiguration().configure().buildSessionFactory();
} 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 SessionFactory getSessionFactory() {
return sessionFactory;
}
public static void shutdown() {
// Close caches and connection pools
getSessionFactory().close();
}
}
HibernateListener:
public class HibernateListener implements ServletContextListener {
/* public void contextInitialized(ServletContextEvent event) {
HibernateUtil.getSessionFactory(); // Just call the static initializer
// of that class
}
public void contextDestroyed(ServletContextEvent event) {
HibernateUtil.getSessionFactory().close(); // Free all resources
}
}*/
#Override
public void contextInitialized(ServletContextEvent arg0) {
System.out.println("\n\tInside contextInitialized()\n")
Session session = HibernateUtil.getSessionFactory().openSession();
session.beginTransaction();
}
#Override
public void contextDestroyed(ServletContextEvent arg0) {
HibernateUtil.shutdown();
}
}
I have also made an entry in web.xml
<listener>
<listener-class>hibernate.HibernateListener</listener-class>
</listener>
I have created a jsp file and try to run a piece of code, which is:
public Employee getEmployeeByLogin(String login){
Employee p= null;
Session session = HibernateUtil.getSessionFactory().getCurrentSession();
Query query = session.createQuery("from employee p where p.login = '" + login +"'");
p = (Employee) query.uniqueResult();
return p;
}
The error I am getting is:
org.apache.jasper.JasperException: org.hibernate.HibernateException: createQuery is not valid without active transaction
I tried to do it similar way as described in https://community.jboss.org/wiki/UsingHibernateWithTomcat# but without success....
So once again. Please help.

How to retrieve sessionFactory from Hibernate 4.3.4.Final?

Previously I was using the following code to configure the sessionFactory, but after upgrading the version of my hibernate from 4.2.1.Final to 4.3.4.Final, I can not retrieve sessionFactory using the following code as ServiceRegistryBuilder() is deprecated.
I used this link to create it but the provided function is not returning any thing therefore it runs into pre-compile error.
private static SessionFactory configureSessionFactory() {
try {
Configuration configuration = new Configuration();
configuration.configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
return sessionFactory;
} catch (HibernateException e) {
System.out.append("** Exception in SessionFactory **");
e.printStackTrace();
}
return sessionFactory;
}
static {
try {
sessionFactory = configureSessionFactory();
} catch (Exception e) {
System.err.println("%%%% Error Creating SessionFactory %%%%");
e.printStackTrace();
}
}
private HibernateUtil() {
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
public static Session getSession() throws HibernateException {
Session session = threadLocal.get();
if (session == null || !session.isOpen()) {
if (sessionFactory == null) {
rebuildSessionFactory();
}
session = (sessionFactory != null) ? sessionFactory.openSession() : null;
threadLocal.set(session);
}
return session;
}
public static void rebuildSessionFactory() {
try {
sessionFactory = configureSessionFactory();
} catch (Exception e) {
System.err.println("%%%% Error Creating SessionFactory %%%%");
e.printStackTrace();
}
}
public static void closeSession() throws HibernateException {
Session session = (Session) threadLocal.get();
threadLocal.set(null);
if (session != null) {
if (session.isOpen()) {
session.close();
}
}
}

In 4.3, you should use the StandardServiceRegistryBuilder instead.
import org.hibernate.boot.registry.StandardServiceRegistryBuilder
StandardServiceRegistryBuilder was added as a new parent of ServiceRegistryBuilder. The rest of the code should be the same. The only place that I have found this documented "clearly" is in the 4.3 JavaDocs for ServiceRegistryBuilder.
One thing that I did not notice was that they changed the ServiceRegistryBuilder.buildServiceRegistry() method to just StandardServiceRegistryBuilder.build(). Therefore, it will require you to change that part of your building process:
new ServiceRegistryBuilder()
.applySettings(configuration.getProperties())
.buildServiceRegistry();
Becomes:
new StandardServiceRegistryBuilder()
.applySettings(configuration.getProperties())
.build();

I tested this one and it works on Hibernate 4.3.6
public class HUtil{
private static SessionFactory sessionFactory;
private static ServiceRegistry serviceRegistry;
public static SessionFactory createSessionFactory() {
Configuration configuration = new Configuration();
configuration.configure();
serviceRegistry = new StandardServiceRegistryBuilder().
applySettings(configuration.getProperties()).build();
sessionFactory = configuration.configure(). buildSessionFactory(serviceRegistry);
return sessionFactory;
}
public static SessionFactory getSessionFactory() {
return createSessionFactory();
} }

Yes, they have deprecated the previous ServiceRegistryBuilder(), here is how you can do it with Hibernate 4.3.4
public void testConnection() throws Exception {
logger.info("Trying to Connect With a DataBase.");
Configuration configuration = new Configuration();
configuration.configure("Your.cfg.xml");
ServiceRegistryBuilder serviceRegistryBuilder = new ServiceRegistryBuilder().applySettings(configuration
.getProperties());
SessionFactory sessionFactory = configuration
.buildSessionFactory(serviceRegistryBuilder.buildServiceRegistry());
Session session = sessionFactory.openSession();
logger.info("Database connection created successfuly.");
}
Source: Create session factory in Hibernate 4

HibernateSessionFactory class doesn't change data from database

In our application we have an HibernateSessionFactory class, that is opening and closing connections. Everything is okay, but when we are updating data in the database, it doesn't change in our application. Unfortunately, we see old data from the database. How can I fix this?
public class HibernateSessionFactory {
private static final ThreadLocal threadLocal = new ThreadLocal();
private static org.hibernate.SessionFactory sessionFactory;
private static Configuration configuration = new Configuration();
private static ServiceRegistry serviceRegistry;
private static final Logger log = Logger.getLogger(
HibernateSessionFactory.class);
static {
try {
configuration.configure();
serviceRegistry = new ServiceRegistryBuilder()
.applySettings(configuration.getProperties())
.buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
} catch (Exception e) {
log.error("Error Creating SessionFactory", e);
}
}
private HibernateSessionFactory() {}
public static Session getSession() throws HibernateException {
Session session = (Session) threadLocal.get();
if (session == null || !session.isOpen()) {
if (sessionFactory == null) {
rebuildSessionFactory();
}
session = (sessionFactory != null) ?
sessionFactory.openSession() : null;
threadLocal.set(session);
}
return session;
}
public static void rebuildSessionFactory() {
try {
configuration.configure();
serviceRegistry = new ServiceRegistryBuilder()
.applySettings(configuration.getProperties())
.buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
} catch (Exception e) {
log.error("Error Creating SessionFactory", e);
}
}
public static void closeSession() throws HibernateException {
Session session = (Session) threadLocal.get();
threadLocal.set(null);
if (session != null) {
session.flush();
session.close();
}
}
public static org.hibernate.SessionFactory getSessionFactory() {
return sessionFactory;
}
public static Configuration getConfiguration() {
return configuration;
}
}
.
#SuppressWarnings("unchecked")
public List<Tauthor> getAuthors() throws HibernateException {
log.debug("getting all authors");
Query queryObject = null;
List<Tauthor> authors = null;
Session session = HibernateSessionFactory.getSession();
try {
String queryString = "from Tauthor";
queryObject = session.createQuery(queryString);
authors = queryObject.list();
} catch (HibernateException e) {
log.error("get all authors failed", e);
throw e;
} finally {
HibernateSessionFactory.closeSession();
}
return authors;
}

You haven't shared your code where you write data to the database. Without that, I can think of only a few reasons as to why your data output is old instead of new data:
Your transactions are not being committed.
Hibernate hasn't written to the database at the time of data queried by you.
Hibernate's cache hasn't been updated, which results in query returning old data.
You should verify that data has been written to the Database with a db developer tool and try disabling all hibernate caching to see if the result changes.

Hibernate Session Factory

In our web application we have a HibernateSessionFactory class, that is opening and closing connections. Everything is okay, but when we are updating data in the database, it doesn't change in our application. Unfortunately, we see old data from the database. How can I fix it?
public class HibernateSessionFactory {
private static final ThreadLocal threadLocal = new ThreadLocal();
private static org.hibernate.SessionFactory sessionFactory;
private static Configuration configuration = new Configuration();
private static ServiceRegistry serviceRegistry;
private static final Logger log = Logger.getLogger(HibernateSessionFactory.class);
static {
try {
configuration.configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties())
. buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
} catch (Exception e) {
log.error("Error Creating SessionFactory",e);
}
}
private HibernateSessionFactory() {
}
public static Session getSession() throws HibernateException {
Session session = (Session) threadLocal.get();
if (session == null || !session.isOpen()) {
if (sessionFactory == null) {
rebuildSessionFactory();
}
session = (sessionFactory != null) ? sessionFactory.openSession()
: null;
threadLocal.set(session);
}
return session;
}
public static void rebuildSessionFactory() {
try {
configuration.configure();
serviceRegistry = new ServiceRegistryBuilder(). applySettings(configuration.getProperties())
.buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
} catch (Exception e) {
log.error("Error Creating SessionFactory",e);
}
}
public static void closeSession() throws HibernateException {
Session session = (Session) threadLocal.get();
threadLocal.set(null);
if (session != null) {
session.flush();
session.close();
}
}
public static org.hibernate.SessionFactory getSessionFactory() {
return sessionFactory;
}
public static Configuration getConfiguration() {
return configuration;
}
}

Hibernate is a sofisticated and complex framework for building a layer between your program and the database, providing an object oriented model to help object oriented programs in their job.
In order to do this, and to be more performat of course, it creates a cache which stores somehow some of the data coming from the database, or going to the database.
I think that this problem is NOT concerning the connection to the database but rather how you save and retrive data.
I'll try to explain my self better: when you query database to save data you do the following steps:
open session
open transaction
build object
flush and save object in session
commit transaction
close transaction
close session
eg
public Boolean saveNewCliente(Cliente c) {
Session s = getSession();
Transaction t = null;
try {
t = s.beginTransaction();
s.save(c);
s.flush();
t.commit();
s.close();
return true;
} catch (Exception e) {
if (t!=null) t.rollback();
System.out.println(e.getMessage());
return false;
}
finally{
s.close();
}
}
A common pitfall happens when you query database to fetch data, is to leave the part relating the transaction out of your "query" steps. As well for saving data you have to
open session
open transaction
build query / criteria
execute query over session
close transaction
close session
If you don't follow this steps is possible that you have stale data in your application, but not in your database. A check may be to execute your update/save-query and check manually in the database if the data has changed/created. If your application then loads stale data you know you do the fetch-query in the wrong way(without using transaction).
Here's a snipped of example
public Cliente get(Integer id) {
Session s = getSession();
Transaction tx = s.beginTransaction();
try {
System.out.println("get cliente by id");
Cliente res = new Cliente();
res = (Cliente) s.get(Cliente.class, id);
tx.commit();
return res;
} catch (Exception e) {
tx.rollback();
System.out.println(e.getMessage());
return null;
}finally{
s.close();
}
}
If you want to furthermore investigate you can suspend the usage of cache by hibernate, you can do it in the following way, but remember that if data is cached there is a reason ;)
This can be useful as a quick test in order to proceed in discovering if the error is due to wrong query usage.
You should add this to your hibernate config xml
<!-- to disable cache -->
<property name="hibernate.cache.use_second_level_cache">false</property>
<property name="hibernate.cache.use_query_cache">false</property>