Pessoal,
estou começando a usar Spring 3 com Hibernate 4 baseando no excelente artigo http://it4beginners.wordpress.com/2012/10/05/spring-3-and-hibernate-4-for-beginners/
e me surgiu uma dúvida a respeito de como o Spring gerência as transações ao final do post vou explicitar a dúvida,
vou postar abaixo os arquivos e códigos para melhor entendimento, e vai servir até de exemplo para quem quiser estudar 
Ferramentas e Tecnologias utilizadas:
- Maven 3.0.5
- jdk1.7.0_15
- Eclipse Juno
- Spring orm 3.2.2
- Hibernate 4.1.10
- PostgreSQL 9.2
A classe entidade “Usuario”
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table
public class Usuario implements Serializable {
private static final long serialVersionUID = 3007826345280433076L;
@Id
private String email;
private String senha;
private String nomeCompleto;
@Column(name="email", unique = true, nullable = false, length = 64)
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Column(name = "senha", nullable = false, length = 16)
public String getSenha() {
return senha;
}
public void setSenha(String senha) {
this.senha = senha;
}
@Column(name = "nome_completo", nullable = false, length = 128)
public String getNomeCompleto() {
return nomeCompleto;
}
public void setNomeCompleto(String nomeCompleto) {
this.nomeCompleto = nomeCompleto;
}
}A classe genérica abstrata DAO “AbstractHibernateDAO”
package br.com.netinspector.model.dao;
import java.io.Serializable;
import java.util.List;
import com.google.common.base.Preconditions;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
@Repository
@Transactional
public abstract class AbstractHibernateDAO< T extends Serializable> {
private final Class< T> clazz;
@Autowired
SessionFactory sessionFactory;
public AbstractHibernateDAO(final Class< T> clazzToSet) {
this.clazz = clazzToSet;
}
@SuppressWarnings("unchecked")
public T getById(final Long id) {
Preconditions.checkArgument(id != null);
return (T) this.getCurrentSession().get(this.clazz, id);
}
@SuppressWarnings("unchecked")
public List< T> getAll() {
return this.getCurrentSession()
.createQuery("from " + this.clazz.getName()).list();
}
public void create(final T entity) {
Preconditions.checkNotNull(entity);
this.getCurrentSession().persist(entity);
}
public void update(final T entity) {
Preconditions.checkNotNull(entity);
this.getCurrentSession().merge(entity);
}
public void delete(final T entity) {
Preconditions.checkNotNull(entity);
this.getCurrentSession().delete(entity);
}
public void deleteById(final Long entityId) {
final T entity = this.getById(entityId);
Preconditions.checkState(entity != null);
this.delete(entity);
}
public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
protected final Session getCurrentSession() {
return this.sessionFactory.getCurrentSession();
}
}Classe DAO “UsuarioDAO”
package br.com.netinspector.model.dao;
import br.com.netinspector.model.domain.Usuario;
public class UsuarioDAO extends AbstractHibernateDAO<Usuario> {
public UsuarioDAO() {
super(Usuario.class);
}
}O arquivo de configuração do Spring “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:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd">
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="org.postgresql.Driver" />
<property name="url" value="jdbc:postgresql://localhost:5432/db_netinspector" />
<property name="username" value="netinspector" />
<property name="password" value="**********" />
</bean>
<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean" >
<property name="dataSource" ref="dataSource" />
<!-- Don't forget to list all your entity classes here -->
<property name="annotatedClasses">
<list>
<value>br.com.netinspector.model.domain.Usuario</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</prop>
<prop key="hibernate.default_schema">netinspector</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.hbm2ddl.auto">update</prop>
</props>
</property>
</bean>
<bean id="txManager"
class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
<tx:annotation-driven transaction-manager="txManager" />
<context:annotation-config />
<!-- Note the usage of abstract="true" and parent="AbstractHibernateDAO" in the implementations-->
<bean id="AbstractHibernateDAO" abstract="true"
class="br.com.netinspector.model.dao.AbstractHibernateDAO"/>
<bean id="UsuarioDAO" parent="AbstractHibernateDAO"
class="br.com.netinspector.model.dao.UsuarioDAO"/>
</beans>a classe APP.java para executar inserindo um registro no banco
package br.com.netinspector;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import br.com.netinspector.model.dao.UsuarioDAO;
import br.com.netinspector.model.domain.Usuario;
public class App {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("ApplicationContext.xml");
Usuario usuario = new Usuario();
usuario.setEmail("Andrelosquei@com.br");
usuario.setNomeCompleto("Andrelosquei Da Silva");
usuario.setSenha("12322");
UsuarioDAO usuarioDAO = (UsuarioDAO) context.getBean("UsuarioDAO");
usuarioDAO.create(usuario);
}
}Esse pequena aplicação está funcionando e o registro está sendo inserido de boa, agora vamos a minha dúvida:
Será que está sendo feito o controle da transação?? Pois se repararem não há nenhuma chamada explícita(pelo menos no código) de “beginTransaction” “commit” etc
Será que a parte do arquivo de conf “ApplicationContext.xml” é responsável pelo gerenciamento da transação?
<bean id="txManager"
class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
<tx:annotation-driven transaction-manager="txManager" />Abraços,
Rogério Martins Manzan