Data Access - Spring Enterprise Recipes: A Problem Solution Approach - page 150

How It Works
To use the contextual session approach, your DAO methods require access to the session factory, which
can be injected via a setter method or a constructor argument. Then, in each DAO method, you get the
contextual session from the session factory and use it for object persistence.
package com.apress.springenterpriserecipes.course.hibernate;
...
import org.hibernate.Query;
import org.hibernate.SessionFactory;
import org.springframework.transaction.annotation.Transactional;
public class HibernateCourseDao implements CourseDao {
private SessionFactory sessionFactory;
public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
@Transactional
public void store(Course course) {
sessionFactory.getCurrentSession().saveOrUpdate(course);
}
@Transactional
public void delete(Long courseId) {
Course course = (Course) sessionFactory.getCurrentSession().get(
Course.class, courseId);
sessionFactory.getCurrentSession().delete(course);
}
@Transactional(readOnly = true)
public Course findById(Long courseId) {
return (Course) sessionFactory.getCurrentSession().get(
Course.class, courseId);
}
@Transactional(readOnly = true)
public List<Course> findAll() {
Query query = sessionFactory.getCurrentSession().createQuery(
"from Course");
return query.list();
}
}
Note that all your DAO methods must be made transactional. This is required because Spring wraps
the SessionFactory with a proxy that expects that Spring's transaction management is in play when
methods on a session are made. It will attempt to find a transaction and then fail, complaining that no
Hibernate session's been bound to the thread. You can achieve this by annotating each method or the
entire class with @Transactional . This ensures that the persistence operations within a DAO method
will be executed in the same transaction and hence by the same session. Moreover, if a service layer
component's method calls multiple DAO methods, and it propagates its own transaction to these
methods, then all these DAO methods will run within the same session as well.