Error there is no Action mapped for namespace/and action name-struts2

Struts2 An error has occurred, always prompt "There is no action mapped for Namespace/and action name" error.

The error code is as follows:

09:36:13,515WARN [Dispatcher] Could not find action or resultthere is no action mapped fornamespace [/] and action name [CSS] associated with context path [/chinaunicom]. -[Unknown Location] at Com.opensymphony.xwork2.DefaultActionProxy.prepare (Defaultactionproxy.java:185) at Org.apache.struts2.impl.StrutsActionProxy.prepare (Strutsactionproxy.java:63) at Org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy (Strutsactionproxyfactory.java:39) at Com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy (Defaultactionproxyfactory.java: 58) at Org.apache.struts2.dispatcher.Dispatcher.serviceAction (Dispatcher.java:534) at Org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction (Executeoperations.java:77) at Org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter ( Strutsprepareandexecutefilter.java:91) at Org.apache.catalina.core.ApplicationFilterChain.internalDoFilter (Applicationfilterchain.java:235) at Org.apache.catalina.core.ApplicationFilterChain.doFilter (Applicationfilterchain.java:206) at Org.apache.catalina.core.StandardWrapperValve.invoke (Standardwrappervalve.java:233) at Org.apache.catalina.core.StandardContextValve.invoke (Standardcontextvalve.java:191) at Org.apache.catalina.core.StandardHostValve.invoke (Standardhostvalve.java:127) at Org.apache.catalina.valves.ErrorReportValve.invoke (Errorreportvalve.java:102) at Org.apache.catalina.core.StandardEngineValve.invoke (Standardenginevalve.java:109) at Org.apache.catalina.connector.CoyoteAdapter.service (Coyoteadapter.java:293) at Org.apache.coyote.http11.Http11Processor.process (Http11processor.java:859) at Org.apache.coyote.http11.http11protocol$http11connectionhandler.process (Http11protocol.java:602) at Org.apache.tomcat.util.net.jioendpoint$worker.run (Jioendpoint.java:489) at Java.lang.Thread.run (Thread.java:619)

Internet query found that this is a beginner frequently encountered problems, leading to the reasons for the main two kinds of errors. Summarized as follows:

1.struts.xml file error. This error is divided into the following categories:

1.1struts.xml file name error. Be sure to pay attention to spelling problems;

1.2struts.xml file placement path error. Be sure to place this file in the SRC directory. After the compilation is successful, verify that it is compiled into the classes directory;

1.3struts.xml file content error. A correct struts.xml file is given below for reference. Note the background color section.

<?XML version= "1.0" encoding= "UTF-8"?><!DOCTYPE struts Public "-//apache software foundation//dtd struts Configuration 2.0//en" "Http://struts.apache.or G/dtds/struts-2.0.dtd "><Struts>    < Packagename= "Default"namespace="/"extends= "Struts-default">        <Actionname= "Login"class= "Com.wanggc.struts2.sample.Struts2Action">        <resultname= "Success">/jsp/result.jsp</result>        </Action>    </ Package></Struts>

2. If you exclude the problem with the Struts.xml file, another possibility is that you have configured your project's startup page in the <welcome-file> information in the Web. xml file. If there is no configuration, the address bar to enter the completion of the URL, such as: http://localhost:8080/Struts2Sample/jsp/login.jsp, the following resource details are not entered when the error will be reported, I was planted on this issue (^_ ^).