请问一下各位大虾, 下面错误是什么原因?
log4j:WARN No appenders could be found for logger (org.springframework.core.CollectionFactory).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.springframework.beans.factory.BeanDefinitionStoreException: Error registering bean with name 'dataSource' defined in class path resource [applicationContext.xml]: Class that bean class [org.apache.commons.dbcp.BasicDataSource] depends on not found; nested exception is java.lang.NoClassDefFoundError: org/apache/commons/pool/impl/GenericObjectPool
java.lang.NoClassDefFoundError: org/apache/commons/pool/impl/GenericObjectPool
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.springframework.util.ClassUtils.forName(ClassUtils.java:109)
at org.springframework.beans.factory.support.BeanDefinitionReaderUtils.createBeanDefinition(BeanDefinitionReaderUtils.java:65)
at org.springframework.beans.factory.xml.DefaultXmlBeanDefinitionParser.parseBeanDefinitionElement(DefaultXmlBeanDefinitionParser.java:466)
at org.springframework.beans.factory.xml.DefaultXmlBeanDefinitionParser.parseBeanDefinitionElement(DefaultXmlBeanDefinitionParser.java:432)
at org.springframework.beans.factory.xml.DefaultXmlBeanDefinitionParser.parseBeanDefinitions(DefaultXmlBeanDefinitionParser.java:347)
at org.springframework.beans.factory.xml.DefaultXmlBeanDefinitionParser.registerBeanDefinitions(DefaultXmlBeanDefinitionParser.java:197)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:295)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:223)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:173)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:148)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:129)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:145)
at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:113)
at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:81)
at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:89)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:262)
at org.springframework.context.support.ClassPathXmlApplicationContext. (ClassPathXmlApplicationContext.java:87)
at org.springframework.context.support.ClassPathXmlApplicationContext. (ClassPathXmlApplicationContext.java:72)
at org.springframework.context.support.ClassPathXmlApplicationContext. (ClassPathXmlApplicationContext.java:63)
at AppContext. (AppContext.java:20)
at AppContext.getInstance(AppContext.java:12)
