类加载的问题have different Class objects for the type used in the signature

如果项目启动时报类似以下的错误：

java.lang.LinkageError: loader constraint violation: when resolving interface method "org.hibernate.engine.SessionFactoryImplementor.getTransactionManager()Ljavax/transaction/TransactionManager;" the class loader (instance of org/jboss/classloader/spi/base/BaseClassLoader) of the current class, org/springframework/orm/hibernate3/SessionFactoryUtils, and the class loader (instance of org/jboss/classloader/spi/base/BaseClassLoader) for resolved class, org/hibernate/engine/SessionFactoryImplementor, have different Class objects for the type javax/transaction/TransactionManager used in the signature

这个问题耗费了我很长一段时间，查阅了很多论坛和技术资料，也用了很多的解决办法，如把Jar包替换掉，查找配置文件……。最后在http://www.jboss.org/community/wiki/ClassLoadingConfiguration 中找到解决方法。

最终的方案就是在项目的WEB-INF下面添加了一个叫jboss-web.xml的文件，内容如下：

<!DOCTYPE jboss-web PUBLIC "-//JBoss//DTD Web Application 5.0//EN"  
"http://www.jboss.org/j2ee/dtd/jboss-web_5_0.dtd"> 
<jboss-web> 
<class-loading java2ClassLoadingCompliance='true'> 
       <loader-repository> 
           com.example:archive=unique-archive-name  
           <loader-repository-config> 
               java2ParentDelegaton=true 
           </loader-repository-config> 
       </loader-repository> 
  </class-loading> 
</jboss-web>