struts2的运行流程问题

web.xml

<welcome-file-list> 

  <welcome-file>index.action</welcome-file> 

</welcome-file-list>

struts.xml

<package name="mainindex" extends="basePackage" namespace="/"> 

  <interceptors> 

    <interceptor name="trimInterceptor" class="com.edps.common.TrimInterceptor"/>  

    <interceptor-stack name="rootStack"> 

      <!-- trim拦截器 -->  

      <interceptor-ref name="trimInterceptor"/>  

      <interceptor-ref name="baseStack"/> 

    </interceptor-stack> 

  </interceptors>  

  <!-- 配置默认拦截器栈 -->  

  <default-interceptor-ref name="rootStack"/>  

  <global-results> 

    <result name="login" type="redirect">/auth!chkin.action</result>  

    <result name="error" type="freemarker">/WEB-INF/template/basicdata/error.ftl</result>  

    <result name="success" type="freemarker">/WEB-INF/template/basicdata/success.ftl</result> 

  </global-results>  

  <action name="index"> 

    <result name="success">system/lightblue1_accordion/main_index.jsp</result> 

  </action>  

  <action name="auth" class="com.edps.action.AuthAction" method="chkin"> 

    <result name="in">system/login/index.jsp</result>  

    <result name="success">system/lightblue1_accordion/main.jsp</result> 

  </action> 

</package>

action类

public class AuthAction extends BaseAction {

        .....

	public String chkin(){

		return "in";

	}

	



	public String login(){

                return SUCCESS;

        ｝

｝

流程
1 程序启动，地址栏显示http://localhost/edps/index.action，在struts.xml中找到<action name="index">，因默认返回success，进入system/lightblue1_accordion/main_index.jsp

2 main_index.jsp里面有<a href="/edps/auth!chkin.action" target="_top">，点击后在struts.xml中找到<action name="auth" class="com.edps.action.AuthAction" method="chkin">，执行AuthAction 中的chkin方法，返回in,进入
<result name="in">system/login/index.jsp</result>对应的index.jsp页面

目前为止，我能理解

3 问题：index.jsp页面里面有 <form method="post" class="login_form" action="<%=path%>/auth!login.action">，提交后 这个，该对struts.xml里面的哪个action呢？我看运行结果是到<result name="success">system/lightblue1_accordion/main.jsp</result>这里
我不理解的是auth!login.action这个，因方法是login,应该要对应<action name="auth" class="com.edps.action.AuthAction" method="login">这样的,为什么会进入<action name="auth" class="com.edps.action.AuthAction" method="chkin">？？还是我的理解有问题？？ 或者auth!login.action这样的，是根据什么来找struts.xml里面的对应action的？