title: conflict for both use @transantional and tx:advice
body: <p>I have some questions on both use <code>@Transactional</code> annotation and xml config <code>tx:advice</code> in the same project.</p>
  
  <ol>
  <li><p>If my class is inside the <code>tx:advice</code>'s pointcut, and i set the annotation <code>@Transactional</code> on the class,which one would become effective? From my simple test,the <code>tx:advice</code> effectived? why?</p></li>
  <li><p>If the first class is not within the <code>tx:advice</code>'s pointcut and i set the <code>@Transactional</code>, then I invoke a method within the <code>tx:advice</code>'s pointcut,would it be conflicted?For I am seem to get the exception: <code>[Already value [org.springframework.jdbc.datasource.ConnectionHolder@14e9851] for key [org.apache.commons.dbcp.BasicDataSource@4dd1b] bound to thread]</code></p></li>
  </ol>