Hibernate 4 - DAO call and sessionFactory bean initialization
I am in the middle of upgrading my old program to Spring 3.2 and Hibernate 4 and I ran into several difficulties with sessionFactory (I used to use hibernateTemplate before).
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I don't think the way to access the DAO is the best way to do it, but I don't see how else to get it to work. If I do a simple DAO object creation (CSSDAO d = new CSSDAOImpl ();) the sessionFactory is always null. If I have what I am doing below it works. What is the proper way to call DAO methods? (please ignore the MVC part of the controller, I know it needs its own work)
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I am opening a new session in every method in DAO. I know this is not correct as I have to get the current session. But every time I try to get the current session, it says it doesn't exist. How is the session "initialized" the first time? I thought it would inject it based on the XML config, but it doesn't seem to do anything. Any thoughts?
hibernate-cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">
<bean id="myDataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="org.apache.derby.jdbc.EmbeddedDriver"></property>
<property name="url" value="jdbc:derby:C:\Users\Steven\MyDB"></property>
</bean>
<bean id="sessionFactory"
class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="packagesToScan" value="net.form" />
<property name="dataSource" ref="myDataSource"></property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.DerbyTenSevenDialect
</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
<property name="annotatedClasses">
<list>
<value>net.form.StyleChooser</value>
</list>
</property>
</bean>
<bean id="transactionManager"
class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
<tx:annotation-driven transaction-manager="transactionManager" />
<bean id="CSSDAO" class="dao.CSSDAOImpl">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
</beans>
DAO:
package dao;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.transaction.annotation.Transactional;
import net.form.StyleChooser;
public class CSSDAOImpl implements CSSDAO {
private SessionFactory sessionFactory;
@Autowired
public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
@Transactional
public List selectAllCSS() {
Session session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();
List l = session.createCriteria(StyleChooser.class).list();
session.flush();
tx.commit();
return l;
}
@Transactional
public StyleChooser selectCSSById(Integer ID) {
Session session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();
StyleChooser sc = (StyleChooser) session.get(StyleChooser.class, ID);
session.flush();
tx.commit();
return sc;
}
@Transactional
public Integer insertCSS(StyleChooser insertCSS) {
Session session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();
Integer id = (Integer) session.save(insertCSS);
session.flush();
tx.commit();
return id;
}
@Transactional
public void deleteCSS(Integer CSSId) {
Session session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();
StyleChooser sc = (StyleChooser) session.get(StyleChooser.class, CSSId);
session.delete(sc);
session.flush();
tx.commit();
}
@Transactional
public void updateCSS(StyleChooser cssWithNewValues) {
Session session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();
session.update(cssWithNewValues);
session.flush();
tx.commit();
}
}
Accessing the DAO ...
package net.controllers;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import net.form.StyleChooser;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.Resource;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.multiaction.MultiActionController;
import dao.CSSDAOImpl;
@Controller
@RequestMapping("/stylechoosertable.html")
public class IndexController extends MultiActionController {
Resource resource = new FileSystemResource(
"C:/Users/Steven/Desktop/Programming/workspace/CSSGeneratorHibernate4/WebContent/WEB-INF/hibernate.cfg.xml");
BeanFactory beanFactory = new XmlBeanFactory(resource);
CSSDAOImpl dao = (CSSDAOImpl) beanFactory.getBean("CSSDAO");
@RequestMapping(method = RequestMethod.GET)
public ModelAndView showIndex(HttpServletRequest request) throws Exception {
List<StyleChooser> styleChooser = dao.selectAllCSS();
return new ModelAndView("stylechoosertable", "styleChooser", styleChooser);
}
}
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A few observations:
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Your getter methods must not use a transaction, that is, they must be non-transactional.
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Add
<tx:annotation-driven transaction-manager="transactionManager"/>
to your config to find out transactional annotations. -
If you are using annotation
@Transactional
then you do not need to use programmatic transactions. Add spread attribute to annotation@Transactional
as@Transactional(propagation=Propagation.REQUIRED)
and leave transaction control in Hibernate. -
The first time you need to open a session, if not close, you can use the same session next time. For getting
session
better use the utility method as shown below:private Session getSession(SessionFactory sessionFactory){ Session session = null; try{ session = sessionFactory.getCurrentSession(); }catch(HibernateException hex){ hex.printStackTrace(); } if(session == null && !session.isClosed()){ session = sessionFactory.openSession(); } }
This way you get the session if available and open a new session otherwise.
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