title: How to use JPA in spring sample petclinic?
body: <p>I am learning spring samples. In the petclinic project, by default it uses jdbc. I change the following line to jpa, and can't run it anymore</p>
  
  <pre><code>/WEB-INF/spring/applicationContext-jpa.xml
  </code></pre>
  
  <p>Here is the error message:</p>
  
  <pre><code>Caused by: java.lang.IllegalStateException: ClassLoader [org.apache.catalina.loader.WebappClassLoader] does NOT provide an 'addTransformer(ClassFileTransformer)' method. Specify a custom LoadTimeWeaver or start your Java virtual machine with Spring's agent: -javaagent:spring-agent.jar
      at org.springframework.context.weaving.DefaultContextLoadTimeWeaver.setBeanClassLoader(DefaultContextLoadTimeWeaver.java:83)
      at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeAwareMethods(AbstractAutowireCapableBeanFactory.java:1418)
      at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1389)
      at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:512)
      ... 35 more
  </code></pre>
  
  <p>Any response would be very helpful.</p>