javax.servlet.ServletException: java.lang.NullPointerException
org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:518)
org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:421)
root cause
java.lang.NullPointerException
org.apache.struts2.views.tiles.TilesResult.doExecute(TilesResult.java:104)
org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:178)
com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:343)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:213)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218)
com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216)
com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:150)
org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:48)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218)
com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216)
com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:123)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218)
com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.intercept(ParametersInterceptor.java:161)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218)
com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216)
com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:105)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219)
com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218)
com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455)
原因：tomcat在加载web.xml文件 没有对tiles 的工厂实例化
解决一：在web.xml中添加：
<context-param>
<param-name>
org.apache.tiles.impl.BasicTilesContainer.DEFINITIONS_CONFIG
</param-name>
<param-value>/WEB-INF/tiles-defs.xml</param-value>
</context-param>
<listener>
<listener-class>
org.apache.struts2.tiles.StrutsTilesListener
</listener-class>
</listener>
解决二：在web.xml添加
<listener>
<listener-class>org.apache.struts2.tiles.StrutsTilesListener</listener-class>
</listener>
<context-param>
<param-name>definitions-config</param-name>
<param-value>/WEB-INF/tiles-defs.xml</param-value>
</context-param>