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.
Related
I have hibernate query, for example get user by id:
public User findById(int id){
SessionFactory sf = HibernateUtil.getSessionFactory();
Session session = sf.openSession();
Transaction tx = null;
User user = null;
try{
tx = session.beginTransaction();
user = (User) session.get(User.class, id);
session.getTransaction().commit();
} catch(HibernateException e){
if(null != tx) tx.rollback();
System.out.println("HibernateException, transaction will be rollbacked");
} catch(Exception e){
e.printStackTrace();
}
finally {
session.close();
}
return user;
}
It's ok for one query, but i need dublicate all of this code to every query.
I need just on single code:
user = (User) session.get(User.class, id);
Is it possible to put other code to another class, method or something else?
Updated
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) {
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}
It is a good practice to keep one Hibernate utility class which will have a static method to provide us the hibernate session. Moreover you can reuse the hibernate session by preventing making a new session on each query by using some simple logic.
Sorry for my english. I learn JavaEE and i dont know proper or not i use session in hibernate. How to use them? I use pattern DAO and hibernate. Tell my how property use session
this is HibernateUtil class
private static final SessionFactory sessionFactory;
static {
try{
sessionFactory = new Configuration().configure("/app/web/landingpage/HibernateConnect/hibernate.cfg.xml").buildSessionFactory();
}catch(Throwable ex) {
System.out.println("Error " + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
public static void close(Session session) {
if (session != null) {
try {
session.close();
} catch (HibernateException ignored) {
System.out.print("Couldn't close Session" + ignored);
}
}
}
And that class makes all operation db CategoryDaoImpl
public class CategoryDaoImpl implements CategoryDao{
private Session session = null;
//get all category
public Collection getAllCategory() {
List categoris = new ArrayList<Category>();
try{
session = HibernateUtil.getSessionFactory().openSession();
categoris = session.createCriteria(Category.class).list();
}catch(Exception e) {
System.out.println("getAllCategory "+ e);
}finally{
if(session != null && session.isOpen())
session.close();
}
return categoris;
}
//get category id
public Category getCategory(int id) {
Category cat = null;
try {
session = HibernateUtil.getSessionFactory().openSession();
cat = (Category) session.load(Category.class, id);
}catch(Exception e) {
System.out.println("getAllCategory "+ e);
}finally{
if(session != null && session.isOpen())
session.close();
}
return cat;
}
//and below few methods that use it the some way session
}
and this servlet take results indexuser
Session session = HibernateUtil.getSessionFactory().getCurrentSession();
session.beginTransaction();
try{
Collection allcategory = Factory.getInstance().getCatDAO().getAllCategory();
request.setAttribute("allcategory", allcategory);
request.getRequestDispatcher("/index.jsp").forward(request, response);
} catch(Exception e) {
System.out.println(e);
} finally{
if(session!=null && session.isOpen())
session.close();
}
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.
Basically session is used to get physical connection with database. So while you performing any DB Operations it will first open Session using sessionFactory and then Session do physical connection with database and then perform your operation and after performing operation you can close it.
Session is light weight.
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.
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>
I'm working on Struts 2 Framework with Hibernate 3.3 and using Oracle 11g. My web project was working fine since 5 months. But recently I'm facing the java.sql.SQLRecoverableException: Closed Connection during some idle time. I'll explain the scenario follows..
My hibernate.cfg.xml configuration is
<property name="hibernate.current_session_context_class">
thread
</propert
<property name="connection.url">jdbc:oracle:thin:#localhost:1521:orcl</property>
<property name="connection.username">user</property>
<property name="connection.password">user</property>
<property name="connection.driver_class">
oracle.jdbc.OracleDriver
</property>
<property name="myeclipse.connection.profile">Oracle</property>
<property name="hibernate.connection.autoReconnect">true</property>
<property name="dialect"> org.hibernate.dialect.Oracle10gDialect </property>
And my HibernateSessionFactory conf is
private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
private static Configuration configuration = new Configuration();
private static org.hibernate.SessionFactory sessionFactory;
private static String configFile = CONFIG_FILE_LOCATION;
static {
try {
configuration.configure(configFile);
sessionFactory = configuration.buildSessionFactory();
} catch (Exception e) {
System.err
.println("%%%% Error Creating SessionFactory %%%%");
//e.printStackTrace();
}
}
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(configFile);
sessionFactory = configuration.buildSessionFactory();
} 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) {
session.close();
}
}
public static org.hibernate.SessionFactory getSessionFactory() {
return sessionFactory;
}
public static void setConfigFile(String configFile) {
HibernateSessionFactory.configFile = configFile;
sessionFactory = null;
}
public static Configuration getConfiguration() {
return configuration;
}
Then the error comes when the following code runs
session = HibernateSessionFactory.getSession();
Query query = session.createQuery(SQL_QUERY);
try {
// session.connection().close();
System.out.println("CLOSED :"
+ session.connection().isClosed());
if (session.connection().isClosed()) {
System.out.println("RECONNECTING.......");
session.reconnect();
}
System.out.println("CLOSED :"
+ session.connection().isClosed());
} catch (Exception e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
for (Iterator it = query.iterate(); it.hasNext();) {
chk = true;
ur = (EmagEnterpriseLogin) it.next();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
When the above snippet runs even though able to session was opened and created query successfully, But fails at Iterating query. First time comes as
Caused By:java.sql.SQLRecoverableException: Closed Connection
But before this error in first try i captured the session.Connection.isClosed() was false. But after first error then keeps on coming as SQL State=null and from second time i could get session.Connection.isClosed() was true. And then reconnecting executes but still the same error repeats.I also tried rebuilding sessionfactory, that too failed. Please help me to solve this issue.
Finally i found the solution for my problem is using third party Connection Provider instead of using Hibernate Native connection provider. I used c3p0 Connection provider , that also given me some problems and i solved that too. The reference link for c3p0 is here.. Hibernate c3p0 Connection NewPooledConnection close Exception