對 visitAction 類進行了註解配置，

但是在訪問 visitAction 的時候，一直出現下面這個異常提示：

22:23:35,387 ERROR DefaultDispatcherErrorHandler:42 - Exception occurred during processing request: Unable to instantiate Action, visitAction,  defined for 'visit_findByPage' in namespace '/'visitAction
Unable to instantiate Action, visitAction,  defined for 'visit_findByPage' in namespace '/'visitAction - action - file:/C:/Programs/apache-tomcat-7.0.81/webapps/crm_1/WEB-INF/classes/struts.xml:46:59
	at com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:314)
	at com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:395)
	at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:194)
	at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:63)
	at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:37)
	at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:58)
	at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:554)
	at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81)
	at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.springframework.orm.hibernate5.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:151)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:962)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1115)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: visitAction
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1892)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1735)
	at com.opensymphony.xwork2.util.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:152)
	at com.opensymphony.xwork2.ObjectFactory.getClassInstance(ObjectFactory.java:135)
	at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:248)
	at com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:163)
	at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:178)
	at com.opensymphony.xwork2.factory.DefaultActionFactory.buildAction(DefaultActionFactory.java:22)
	at com.opensymphony.xwork2.ObjectFactory.buildAction(ObjectFactory.java:148)
	at com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:295)
	... 29 more
 

檢查了 javaBean 是否配置對了，service 是否呼叫對了，核對遍了這些之後，無果，在網上找了半天，都說是：

<package name="***" extends="struts-default" namespace="/">  中的 namespace 屬性沒有配置，小生很鬱悶。

甚至懷疑自己 action 的呼叫路徑錯了，所以找不到對應的 action，最後琢磨了一遍上面的程式碼提示，覺得 namespace 是個啟發！

原來，在 application.xml 配置中開啟的註解掃描路徑是“com.test” ： <context:component-scan base-package="com.test"/>

但是我編寫的 action 包名路徑為：com.web.action 註解掃描不到，當然找不到 action 異常咯！

哎呀，這是多麼愚蠢的錯誤，謹記！