com/opensymphony/xwork2/spring/SpringObjectFactory.java:220:-1问题出现的原因及解决办法

严重: Exception starting filter struts2 
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:437) 
 at org.apache.struts2.dispatcher.FilterDispatcher.init(FilterDispatcher.java:195) 
 at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:275) 
 at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:397) 
 at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:108) 
 at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3709) 
 at org.apache.catalina.core.StandardContext.start(StandardContext.java:4356) 
 at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791) 
 at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771) 
 at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525) 
 at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:626) 
 at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:553) 
 at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:488) 
 at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1215) 
 at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:293) 
 at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117) 
 at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1337) 
 at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1601) 
 at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610) 
 at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1590) 
 at java.lang.Thread.run(Unknown Source) 
Caused by: java.lang.NullPointerException 
 at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:220) 
 at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyResultType(XmlConfigurationProvider.java:530) 
 at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addResultTypes(XmlConfigurationProvider.java:501) 
 at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:457) 
 at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:275) 
 at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:111) 
 at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:204) 
 at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66) 
 at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:380) 
 at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:424) 
 ... 20 more 
2011-8-28 1:19:47 org.apache.catalina.core.StandardContext start 
严重: Error filterStart 
2011-8-28 1:19:47 org.apache.catalina.core.StandardContext start 

严重: Context [] startup failed due to previous errors

一、原因：

      问题处在你导入的“Struts2 Spring Libraries”库下的“Struts2-spring-plugin-2.2.1.jar”jar包下的struts-plugin.xml里。如下图：

       问题出现的具体位置在上图所示的第29行的代码，这段代码如下：

<bean type="com.opensymphony.xwork2.ObjectFactory" name="spring" class="org.apache.struts2.spring.StrutsSpringObjectFactory" /> 
       这 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。但是 在工程的web.xml中 没有配置 加载spring ApplicationContext相关的listener ，从而导致了启动时出现的问题：com/opensymphony/xwork2/spring/SpringObjectFactory.java:220:-1。  

二、解决办法

在工程的web.xml中 配置  加载spring ApplicationContext相关的listener ，配置的代码如下：

    <context-param> 
        <param-name> 
            contextConfigLocation 
        </param-name> 
        <param-value> 
            /WEB-INF/applicationContext.xml 
        </param-value> 
    </context-param> 
    <listener> 
        <listener-class> 
            org.springframework.web.context.ContextLoaderListener 
        </listener-class> 
    </listener>

终于解决了这个小问题，记录一下，方便查看和回顾，也希望能帮到遇到这个问题需要寻求帮助的朋友。