spring2.0的问题

为什么我用Eclipse5.5加入spring2.0和hibernate测试一个小程序时，抱这样的错误：
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'baseSource' defined in class path resource [applicationContext.xml]: Instantiation of bean failed; nested exception is java.lang.NoClassDefFoundError: org/apache/commons/pool/impl/GenericObjectPool
Caused by: java.lang.NoClassDefFoundError: org/apache/commons/pool/impl/GenericObjectPool
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.getDeclaredConstructor(Unknown Source)~~~~~
但是我把有关用spring1.2写程序用导的有关(commons-dbcp）,等包导进来来就没有问题了，是什么原因，那位高手能帮助一下。