struts2.x获取不存在的action404错误与捕获页面500错误

404错误的捕获：

<struts>
<package name="default" extends="struts-default">
<default-action-ref name="error">
</default-action-ref>
<action name="testDispatcher" class="com.struts.action.TestDispatcher">
<result>/testDispatcher.jsp</result>
</action>
<action name="error">
<result>/error.jsp</result>
</action>
</package>
</struts> <struts>
<package name="default"