Parsing configuration file [struts-default.xml]
Parsing configuration file [struts-plugin.xml]
Parsing configuration file [struts.xml]
Dispatcher initialization failed
Unable to load configuration. - [unknown location]
    at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:69)
    at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:371)
    at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:415)
    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:4071)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4725)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
    at org.apache.catalina.core.StandardService.start(StandardService.java:525)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:45)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:612)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: Cannot locate the chosen ObjectFactory implementation: spring - [unknown location]
    at org.apache.struts2.config.BeanSelectionProvider.alias(BeanSelectionProvider.java:293)
    at org.apache.struts2.config.BeanSelectionProvider.alias(BeanSelectionProvider.java:264)
    at org.apache.struts2.config.BeanSelectionProvider.register(BeanSelectionProvider.java:202)
    at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:180)
    at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)

    ... 22 more

出現此問題的原因是  在 struts.xml 裡  <constant name="struts.objectFactory" value="spring" /> objectFactory採用的spring 需要新增   struts2-spring-plugin-2.2.1.1.jar 包

Initializing Struts-Spring integration...
********** FATAL ERROR STARTING UP STRUTS-SPRING 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>
Dispatcher initialization failed
java.lang.NullPointerException
    at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:220)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyResultType(XmlConfigurationProvider.java:530)

在web.xml裡新增

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext*.xml</param-value>
  </context-param>

<listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>