struts2项目启动时报异常：com.opensymphony.xwork2.spring.SpringObjectFactory
tomcat启动报错：
Class: com.opensymphony.xwork2.spring.SpringObjectFactory
File: SpringObjectFactory.java
Method: getClassInstance
Line: 220 - com/opensymphony/xwork2/spring/SpringObjectFactory.java:220:-1
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:428)
at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:69)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:51)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:295)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3838)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4488)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
at org.apache.catalina.core.StandardService.start(StandardService.java:519)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
at org.apache.catalina.startup.Catalina.start(Catalina.java:581)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: java.lang.NullPointerException
at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:220)
Class: com.opensymphony.xwork2.spring.SpringObjectFactory File: SpringObjectFactory.java Method: getClassInstance Line: 220 - com/opensymphony/xwork2/spring/SpringObjectFactory.java:220:-1 at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:428) at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:69) at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:51) at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:295) at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422) at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115) at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3838) at org.apache.catalina.core.StandardContext.start(StandardContext.java:4488) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045) at org.apache.catalina.core.StandardHost.start(StandardHost.java:785) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045) at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443) at org.apache.catalina.core.StandardService.start(StandardService.java:519) at org.apache.catalina.core.StandardServer.start(StandardServer.java:710) at org.apache.catalina.startup.Catalina.start(Catalina.java:581) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414) Caused by: java.lang.NullPointerException at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:220)
原因：
struts2导入的jar包中加入了struts-spring-plugin这个插件的jar
<dependency> <groupId>org.apache.struts</groupId> <artifactId>struts2-spring-plugin</artifactId> <version>2.2.1</version> </dependency>
但是工程web.xml中没有配置加载spring ApplicationContext相关的listener
<listener>
<listener-class>
org.springframework.web.context.ContextLoaderListener
</listener-class>
</listener>
<listener> <listener-class> org.springframework.web.context.ContextLoaderListener </listener-class> </listener>
原理：
查看struts2插件struts2-spring-plugin中的strtus-plugin.xml
<struts>
<beantype="com.opensymphony.xwork2.ObjectFactory"name="spring"class="org.apache.struts2.spring.StrutsSpringObjectFactory"/>
<!-- Make the Spring object factory the automatic default -->
<constantname="struts.objectFactory"value="spring"/>
<constantname="struts.class.reloading.watchList"value=""/>
<constantname="struts.class.reloading.acceptClasses"value=""/>
<constantname="struts.class.reloading.reloadConfig"value="false"/>
<packagename="spring-default">
<interceptors>
<interceptorname="autowiring"class="com.opensymphony.xwork2.spring.interceptor.ActionAutowiringInterceptor"/>
<interceptorname="sessionAutowiring"class="org.apache.struts2.spring.interceptor.SessionContextAutowiringInterceptor"/>
</interceptors>
</package>
</struts>
<struts>
<bean type="com.opensymphony.xwork2.ObjectFactory" name="spring" class="org.apache.struts2.spring.StrutsSpringObjectFactory" />
<!-- Make the Spring object factory the automatic default -->
<constant name="struts.objectFactory" value="spring" />
<constant name="struts.class.reloading.watchList" value="" />
<constant name="struts.class.reloading.acceptClasses" value="" />
<constant name="struts.class.reloading.reloadConfig" value="false" />
<package name="spring-default">
<interceptors>
<interceptor name="autowiring" class="com.opensymphony.xwork2.spring.interceptor.ActionAutowiringInterceptor"/>
<interceptor name="sessionAutowiring" class="org.apache.struts2.spring.interceptor.SessionContextAutowiringInterceptor"/>
</interceptors>
</package>
</struts>
注意下面部分，表明该插件引入工程后，会自动设置Struts的ObjectFactory为StrutsSpringObjectFactory，从而让Spring的IOC容器来托管Struts的Action。所以导致了启动的问题。
<beantype="com.opensymphony.xwork2.ObjectFactory"name="spring"class="org.apache.struts2.spring.StrutsSpringObjectFactory"/>
<!-- Make the Spring object factory the automatic default -->
<constantname="struts.objectFactory"value="spring"/>
<bean type="com.opensymphony.xwork2.ObjectFactory" name="spring" class="org.apache.struts2.spring.StrutsSpringObjectFactory" />
<!-- Make the Spring object factory the automatic default -->
<constant name="struts.objectFactory" value="spring" />
记录一下错误，方便查看。
文章摘录自：http://javeye.iteye.com/blog/940122/