Using Spring to manage Hibernate sessions in Struts2 (and other web frameworks)

<?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:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans 
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       http://www.springframework.org/schema/tx 
       http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
       http://www.springframework.org/schema/aop 
       http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

  <!-- The singleton hibernate session factory -->
  <bean id="sessionFactory" scope="singleton"
    class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
    <property name="configLocation" value="classpath:hibernate.cfg.xml" />
  </bean>

  <!-- Spring's hibernate transaction manager, in charge of making hibernate sessions/txns -->
  <bean id="transactionManager"
    class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory" />
  </bean>

  <!-- So classes/functions with @Transactional get a hibernate txn -->
  <tx:annotation-driven />
  
  <!-- The singleton business services class, to be given to the actions -->
  <bean id="services" class="services.Services" scope="singleton">
    <property name="sessionFactory" ref="sessionFactory" />
  </bean>
  
</beans>

package services;
import org.springframework.transaction.annotation.Transactional;
import org.hibernate.SessionFactory;
import org.hibernate.Session;
import data.Event; // An example of a hibernate data class

// This class is the business services tier in the application.
// @Transactional is needed so that a Hibernate transaction is set up,
//  otherwise updates won't have an affect
@Transactional
public class Services {
  // So Spring can inject the session factory
  protected SessionFactory sessionFactory;
  public void setSessionFactory(SessionFactory value) {
    sessionFactory = value;
  }

  // Shortcut for sessionFactory.getCurrentSession()
  protected Session sess() {
    return sessionFactory.getCurrentSession();
  }

  // Example of a typical business service function
  public Event getEventById(long id) {
    return (Event) sess().load(Event.class, id);
  }
}

<!-- Spring -->
  <listener> <!-- Required for the struts2 spring plugin to work -->
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
  <filter> <!-- Get spring to keep the session open for the whole request, so hibernate's lazy loads work -->
    <filter-name>openSessionInViewFilter</filter-name>
    <filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>openSessionInViewFilter</filter-name>
    <url-pattern>/*</url-pattern> 
  </filter-mapping>

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
  <session-factory>
    <!-- Database connection settings -->
    <property name="connection.driver_class">net.sourceforge.jtds.jdbc.Driver</property>
    <property name="connection.url">jdbc:jtds:sqlserver://DATABASE-SERVER-NAME/DATABASE-SCHEMA</property>
    <property name="connection.username">USERNAME</property>
    <property name="connection.password">PASSWORD</property>
    <property name="dialect">org.hibernate.dialect.SQLServerDialect</property>

    <!--
      Enable c3p0 connection pooling, because hibernate pooling is not
      prod-ready. Apparently connection.provider_class is needed in
      hibernate 3+
    -->
    <property name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
    <property name="c3p0.max_size">100</property>
    <property name="c3p0.min_size">1</property>
    <property name="c3p0.idle_test_period">30</property>

    <!-- Echo all executed SQL to stdout for debugging -->
    <property name="show_sql">true</property>

    <!-- All the entity classes for hibernate to check for annotations here -->
    <mapping class="data.Whatever" />
  </session-factory>
</hibernate-configuration>

package actions.base;

import services.Services;
import com.opensymphony.xwork2.ActionSupport;

public class SomeAction extends ActionSupport {
  // So that spring can inject the business singleton
  protected Services services;
  public void setServices(Services value) {
    services=value;
  }
  
  public String execute() {
    Event event = services.getEventById(1); // Just an example
    return "success";
  }
}