Creating persistance layer with spring/hibernate

I'm trying to create a persistance project so it can be re-used by some other projects I'm building on top. I.e it will be used by a web service/spring mvc project and by standalone jar which does some file processing.

I've used hibernate with spring mvc before but never as a standalone executable java jar so I have everything setup and working(application context) :

<?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"
        xmlns:context="http://www.springframework.org/schema/context"
        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">

    <!-- Enable annotation style of managing transactions -->
    <tx:annotation-driven transaction-manager="transactionManager" />

    <!-- Root Context: defines shared resources visible to all other web components -->

    <!-- HIBERNATE -->
    <bean id="propertyConfigurer"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="classpath:spring.properties" />
    </bean>

    <bean id="dataSource" class=开发者_JS百科"com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
    <property name="driverClass" value="${jdbc.driverClassName}" />
    <property name="jdbcUrl" value="${jdbc.databaseurl}" />
    <property name="user" value="${jdbc.username}" />
    <property name="password" value="${jdbc.password}" />
    <property name="acquireIncrement" value="5" />
    <property name="idleConnectionTestPeriod" value="60"/>
    <property name="maxPoolSize" value="100"/>
    <property name="maxStatements" value="50"/>
    <property name="minPoolSize" value="10"/>
    </bean>

    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="mappingResources">
            <list>      <value>com/project/utility/persistence/mapping/TestProp.hbm.xml</value>
            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">${jdbc.dialect}</prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
    </bean>


    <bean id="transactionManager"
        class="org.springframework.orm.hibernate3.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>

    <!-- END HIBERNATE -->
</beans>

When I test it from main class everything looks ok with mapping/dependencies :

public static void main(String[] args) {
        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("appCtx.xml");
    }

What I want to do next is to build few dao classes which will get some data and I'd build some interface above that so it can be re-used by both webservice and processing tool as a jar(maven dependency).

In order to build dao classes I need sessionFactory to be != null always. How do I do this?

There are many approaches to this. One solution I use is to use the javax.persistence.PersistenceContext annotation. Spring will respect this annotation and inject a proxy to a thread local EntityManager. Provided your DAO is created by Spring this allows access to the entity manager from within your DAO.

public class DAO {

  private EntityManager entityManager;
  @PersistenceContext
  public void setEntityManager(EntityManager entityManager) {
    this.entityManager = entityManager;
  }

}

@Repository
public class MyDAO {

    @Autowired
    private SessionFactory sessionFactory;

    // ...
}

and add the MyDAO bean to the context XML file, or simply add the following lines to this file:

<context:annotation-config />
<context:component-scan base-package="one.of.the.parent.packages.of.your.dao" />