Summary of Struts2 about "there is no action mapped for Namespace/and action name"

Today is debugging a basic Struts2 skeleton applet. Always prompt "There is no action mapped for Namespace/and action name" error. 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:

One, struts.xml file error. This error is divided into the following categories: 1,struts.xml file name error. Be sure to pay attention to spelling problems; 2,struts.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, and that the 3,struts.xml file contents are incorrect. 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.org/dtds/struts-2.0.dtd" >

<struts>
<package name= "Default" namespace= "/" extends= "Struts-default" >
<action name= "Login" class= "Com.wanggc.struts2.sample.Struts2Action" >
<result name= "Success" >/jsp/result.jsp</result>
</action>
</package>
</struts>

Second, if the problem of the Struts.xml file is excluded, another possibility is that the <welcome-file> information in the Web. xml file is configured with its own project startup page. 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 (^_ ^).

Three appeared for another reason, the action name is wrong, look at the package, will certainly be wrong