Hibernate integration with Spring - spring

Question

I have a problem about integrating Hibernate with Spring:
My hibernate.cfg.xml
<?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>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.password">123456</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/CODEL</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.current_session_context_class">
org.springframework.orm.hibernate4.SpringSessionContext
</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<mapping resource="com/model/Contact.hbm.xml" />
</session-factory>
</hibernate-configuration>
My applicationContext.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: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.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">
<bean id="contactdao" class="com.dao.ContactDAO" scope="prototype" />
<bean id="userdao" class="com.dao.UserDAO" scope="prototype" />
<bean id="groupdao" class="com.dao.GroupDAO" scope="prototype" />
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
<property name="url" value="jdbc:mysql://localhost:3306/CODEL"></property>
<property name="username" value="root"></property>
<property name="password" value="123456"></property>
</bean>
<bean id="mySessionFactory"
class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="dataSource" ref="dataSource"></property>
<property name="configLocation">
<!-- chemin vers le fichier hibernate de config. ça évite d'avoir un composant
datasource -->
<value>classpath:hibernate.cfg.xml</value>
</property>
</bean>
<tx:advice id="txAdvice">
<tx:attributes>
<tx:method name="get*" read-only="true" timeout="-1" />
<tx:method name="sav*" propagation="REQUIRED" />
<tx:method name="find*" read-only="true" />
</tx:attributes>
</tx:advice>
<aop:config>
<aop:advisor pointcut="execution(* com.dao.ContactDAO.*(..))"
advice-ref="txAdvice" />
</aop:config>
<bean id="transactionManager"
class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory" ref="mySessionFactory" />
</bean>
<bean id="hibernateTemplate" class="org.springframework.orm.hibernate4.HibernateTemplate">
<property name="sessionFactory" ref="mySessionFactory"></property>
<property name="checkWriteOperations" value="false" />
</bean>
<bean id="contactDAO" class="com.dao.ContactDAO">
<property name="hibernateTemplate" ref="hibernateTemplate" />
</bean>
</beans>
My dao
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.orm.hibernate4.HibernateTemplate;
import org.springframework.orm.hibernate4.support.HibernateDaoSupport;
import com.model.Contact;
import com.model.Entreprise;
import com.model.PhoneNumber;
import com.util.HibernateUtil;
public class ContactDAO extends HibernateDaoSupport {
private HibernateTemplate hibernateTemplate;
public ContactDAO() {
}
public void setHibernateTemplate(SessionFactory sessionFactory) {
this.hibernateTemplate = new HibernateTemplate(sessionFactory);
}
public List<Contact> listAllContacts() {
List<Contact> listContacts = (List<Contact>) this.hibernateTemplate
.find("from CODEL.Contact");
return listContacts;
}
}
I've got an error NullPointerException at the line of this.hibernateTemplate.find... By println, I've seen it null. Thanks for any suggestion and explanation why my code produced this error.

Answer 1

Can you please update your ContactDAO setHibernateTemplate method to set the hibernateTemplate, instead of creating a new HibernateTemplate, for example
public void setHibernateTemplate(HibernateTemplate hibernateTemplate) {
this.hibernateTemplate = hibernateTemplate;
}
currently your setter method is taking sessionFactory, so its not calling the actual setter for hibernate template, which could be causing the null pointer exception.

Answer 2

Let's say you have to tell Spring how different components communicate between them.You need annotations to linked them together.
The easiest way is letting Spring detects these links itself.
So in applicationContext.xml, add this line of code :
<context:component-scan base-package="com.example.pkg" />
Then, Spring will search for every components in this package.
You need also declare the existence of your comopents.
#Repository(value = "contactDAO")
public class ContactDAO extends HibernateDaoSupport
And you have to link the bean created in context to your class attribut:
#Autowired
private HibernateTemplate hibernateTemplate;
Then you can use this HibernateTemplate object without setMethod because it initialization is done by Spring.