在web的lib下，加了struts2-spring-plugin-2.0.6。jar包文件，我只用struts，没有配置与spring有关的任何内容，结果显示错误信息：
FATAL [org.apache.struts2.spring.StrutsSpringObjectFactory:74] ********** FATAL ERROR STARTING UP SPRING-STRUTS INTEGRATION **********
Looks like the Spring listener was not configured for your web app!
Nothing will work until WebApplicationContextUtils returns a valid ApplicationContext.
You might need to add the following to web.xml:
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
2007-11-21 14:34:10 org.apache.catalina.core.StandardContext filterStart
严重: Exception starting filter struts2
java.lang.NullPointerException
at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:188)

把struts2-spring-plugin-2.0.6.jar从lib中删除一切都正常，说明只要有这个包，则必须配置spring监听。