com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance

Struts2启动异常
Class: com.opensymphony.xwork2.spring.SpringObjectFactory
File: SpringObjectFactory.java
Method: getClassInstance
Line: 209 - com/opensymphony/xwork2/spring/SpringObjectFactory.java:209:-1
Caused by: java.lang.NullPointerException  at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:209)

原因两个：
1.lib中多导入包的原因：去掉struts2-spring-plugin-2.1.8包即可，因为没有用到spring。有时也可能是其它包冲突的原因。
2.还有的原因是用spring了，却没加监听器，在web.xml里面加上
<listener>
     <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>