做例子时遇到的问题
严重: Exception starting filter struts2java.lang.RuntimeException: java.lang.
RuntimeException: 
com.opensymphony.xwork2.inject.DependencyException: com.opensymphony.xwork2.inject.ContainerImpl$MissingDependencyException: No mapping found for dependency [type=java.lang.String, name='actionPackages'] in public void org.apache.struts2.config.ClasspathPackageProvider.setActionPackages(java.lang.String).
	at com.opensymphony.xwork2.inject.ContainerBuilder$4.create(ContainerBuilder.java:137)
	at com.opensymphony.xwork2.inject.Scope$2$1.create(Scope.java:49)
	at com.opensymphony.xwork2.inject.ContainerImpl.getInstance(ContainerImpl.java:492)
	at com.opensymphony.xwork2.inject.ContainerImpl$8.call(ContainerImpl.java:525)
	at com.opensymphony.xwork2.inject.ContainerImpl.callInContext(ContainerImpl.java:558)
	at com.opensymphony.xwork2.inject.ContainerImpl.getInstance(ContainerImpl.java:523)
	at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:188)	
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:55)
	at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:371)
	at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:424)
	at org.apache.struts2.dispatcher.FilterDispatcher.init(FilterDispatcher.java:213)
	at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:221)
	at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:302)
	at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:78)
	at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3635)
	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4222)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1014)
	at org.apache.catalina.core.StandardHost.start(StandardHost.java:736)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1014)
	at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
	at org.apache.catalina.core.StandardService.start(StandardService.java:448)
	at org.apache.catalina.core.StandardServer.start(StandardServer.java:700)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:552)
	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:295)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:433)
Caused by: java.lang.RuntimeException: com.opensymphony.xwork2.inject.DependencyException: com.opensymphony.xwork2.inject.ContainerImpl$MissingDependencyException: No mapping found for dependency [type=java.lang.String, name='actionPackages'] in public void org.apache.struts2.config.ClasspathPackageProvider.setActionPackages(java.lang.String).
	at com.opensymphony.xwork2.inject.ContainerImpl.inject(ContainerImpl.java:480)
	at com.opensymphony.xwork2.inject.ContainerImpl$7.call(ContainerImpl.java:517)
	at com.opensymphony.xwork2.inject.ContainerImpl.callInContext(ContainerImpl.java:565)
	at com.opensymphony.xwork2.inject.ContainerImpl.inject(ContainerImpl.java:515)
	at com.opensymphony.xwork2.config.impl.LocatableFactory.create(LocatableFactory.java:32)
	at com.opensymphony.xwork2.inject.ContainerBuilder$4.create(ContainerBuilder.java:135)
	... 28 more
Caused by: com.opensymphony.xwork2.inject.DependencyException: com.opensymphony.xwork2.inject.ContainerImpl$MissingDependencyException: No mapping found for dependency [type=java.lang.String, name='actionPackages'] in public void org.apache.struts2.config.ClasspathPackageProvider.setActionPackages(java.lang.String).