Spring (@Transact) - try catch sem funcionamento

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
        id="WebApp_ID" version="2.5">    
        <!-- CONFIGURANDO O SPRING -->
        <context-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>
                /WEB-INF/applicationContext.xml
            </param-value>
        </context-param>
          
		<filter>
			<filter-name>oemInViewFilter</filter-name>
			<filter-class>
				org.springframework.orm.hibernate3.support.OpenSessionInViewFilter
			</filter-class>
			<init-param>
				<param-name>sessionFactoryBeanName</param-name>
				<param-value>sessionFactory</param-value>
			</init-param>
		
		</filter>
		
		<filter-mapping>
			<filter-name>oemInViewFilter</filter-name>
			<url-pattern>/*</url-pattern>
		</filter-mapping>
      	      
        <listener>
            <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
        </listener>
                	     
        <listener>
            <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
        </listener>
        
        <!-- CONFIGURANDO O BLAZEDS -->
        <context-param>
            <param-name>flex.class.path</param-name>
            <param-value>/WEB-INF/flex/hotfixes</param-value>
        </context-param>
     
        <!-- CONFIGURANDO O MESSAGEBROKER SERVLET -->
        <servlet>
            <servlet-name>MessageBrokerServlet</servlet-name>
            <display-name>MessageBrokerServlet</display-name>
            <servlet-class>
                flex.messaging.MessageBrokerServlet
            </servlet-class>
            <init-param>
                <param-name>services.configuration.file</param-name>
                <param-value>/WEB-INF/flex/services-config.xml</param-value>
            </init-param>
            <init-param>
                <param-name>flex.write.path</param-name>
                <param-value>/WEB-INF/flex</param-value>
            </init-param>
            <load-on-startup>1</load-on-startup>
        </servlet>
        <servlet-mapping>
            <servlet-name>MessageBrokerServlet</servlet-name>
            <url-pattern>/messagebroker/*</url-pattern>
        </servlet-mapping>     
		

     
        <display-name>BLA BLA BLA</display-name>
        
        <welcome-file-list>
            <welcome-file>index.html</welcome-file>
            <welcome-file>index.htm</welcome-file>
            <welcome-file>index.jsp</welcome-file>
        </welcome-file-list>
     
    </web-app>

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
    	xmlns:aop="http://www.springframework.org/schema/aop"    
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:p="http://www.springframework.org/schema/p"
        xmlns:context="http://www.springframework.org/schema/context"
        xmlns:jee="http://www.springframework.org/schema/jee"
        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/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
                http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
                http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd
                http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd"
        default-lazy-init="true"> <!-- INICIALIZAÇÃO TARDIA -->          
	    
        
        <!-- DEFINE OS PACOTES/SUBPACOTES QUE SERAO SCANEADOS PELO SPRING -->
	    <context:component-scan base-package="controlador" />
  	    <context:component-scan base-package="modelo" />
   	    <context:component-scan base-package="util" /> 
    	
        <!-- CARREGA ARQUIVO DE CONFIGURACAO JDBC-->        
        <context:property-placeholder location="classpath:util/jdbc.properties" />      
		<tx:annotation-driven />
				
		<bean id="IBaseDAO" class="modelo.interfaces.base.IBaseDAO" p:sessionFactory-ref="sessionFactory" />
          				
        <!-- CONFIGURACAO DO DATASOURCE -->
        <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
            <property name="driverClassName">
                <value>${jdbc.driverClassName}</value>
            </property>
            <property name="url">
                <value>${jdbc.url}</value>
            </property>
            <property name="username">
                <value>${jdbc.username}</value>
            </property>
            <property name="password">
                <value>${jdbc.password}</value>
            </property>
        </bean>
        
     	<!-- TRANSACTION MANAGER -->
        <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">        
            <property name="sessionFactory">
                <ref local="sessionFactory"/>
            </property>
        </bean>          
     
        <!-- CONFIGURACAO DO SESSIONFACTORY DO HIBERNATE -->
        <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">     
            <property name="dataSource">
                <ref local="dataSource" />
            </property>   
	        	
            <!-- CONFIGURACAO DO HIBERNATE -->
            <property name="hibernateProperties">
	
                <props>
                    <prop key="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</prop>
                    <prop key="hibernate.show_sql">true</prop>
                </props>
            </property>
			
			<property name="packagesToScan" value="modelo.dto" />	    
     
            <property name="eventListeners">
                <map>
                    <entry key="merge">
                        <bean class="org.springframework.orm.hibernate3.support.IdTransferringMergeEventListener"/>
                    </entry>
                </map>
            </property>                 
        </bean>        

   
  
</beans>

ObjetoBO.salvar(objeto);

class ObjetoBO {

      @Transactional(rollbackFor=Exception.class)
      public void salvar(Objeto objeto) {
           try {
                 ObjetoDAO.salvar(objeto);
           } catch(Exception e) {
                  // se você capturar alguma exception aqui, e não propogar, o TransactionManager vai pensar que está tudo ok, e irá comitar. Se quiser fazer algum tratamento, faca aqui e depois lance a exceção normalmente com um throws :)
           }
      }
}


class ObjetoDAO {

      @Transactional(rollbackFor=Exception.class)
      public void salvar(Objeto objeto) {
           GenericDAO.salvar(objeto);
            // você não pode dar catch de exceção aqui
      }
}

class GenericDAO {

       EntityManager entityManager;

      @Transactional(rollbackFor=Exception.class)
      public void salvar(Objeto objeto) {
           entityManager.persist(objeto);
           // você não pode dar catch de exceção aqui
      }
}