//摘自org.apache.struts.action.ActionServlet.

 public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws IOException, ServletException {
    process(request, response);
    }
    
    public void doPost    (HttpServletRequest request, HttpServletResponse response)
    throws IOException, ServletException {
    process(request, response);
    }

     protected void process(HttpServletRequest request, HttpServletResponse response)
    throws IOException, ServletException {
    //根据请求选择恰当的应用模块
    ModuleUtils.getInstance().selectModule(request,this.getServletContext());
    ModuleConfig config = getModuleConfig(request);
    //获取模块相关的RequestProcessor实例
    RequestProcessor processor = getProcessorForModule(config);
    if (processor == null)
        processor = getRequestProcessor(config);
        //调用processor实例的process()方法处理请求
    processor.process(request, response);
    }

//摘自RequestProcessor
     public void process(HttpServletRequest request, HttpServletResponse response)throws IOException, ServletException
     {
         //用一个特殊的包装对象把Muiltipart请求包装起来
         request = processMultipart(request);
         //验证我们用来选择映射的路径组件
         String path = processPath(request, response);
         
         if (path != null) 
         {
            if (log.isDebugEnabled())
            log.debug("Processing a '" + request.getMethod() + "' for path '" + path + "'");
           //有请求时， 为当前用户选择一个Locale对象
            processLocale(request, response);
            //有请求时，设置内容类型和no-caching字头
            processContent(request, response);
            processNoCache(request, response);
            if (processPreprocess(request, response))
            {
                processCachedMessages(request, response);
                //验证这个请求的映射
                ActionMapping mapping = processMapping(request, response, path);
                if (mapping != null && processRoles(request, response, mapping)) 
                {
                    //处理和这个请求相关的任何ActionForm bean
                    ActionForm form = processActionForm(request, response, mapping);
                    processPopulate(request, response, form, mapping);
                    if (processValidate(request, response, form, mapping)&& processForward(request, response, mapping)&& processInclude(request, response, mapping)) 
                    {
                        //创建或获取Action实例来处理这项请求
                        Action action = processActionCreate(request, response, mapping);
                        if (action != null)
                        {
                            //调用Action实例本身
                            ActionForward forward = processActionPerform(request, response,action, form, mapping);
                            //处理所返回的ActionForward实例
                            processForwardConfig(request, response, forward);
                        }
                    }
                }
            }
         }
     }

 <servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <init-param>
      <param-name>config</param-name>
      <param-value>/WEB-INF/struts-config.xml</param-value>
    </init-param>
    <init-param>
      <param-name>debug</param-name>
      <param-value>3</param-value>
    </init-param>
    <init-param>
      <param-name>detail</param-name>
      <param-value>3</param-value>
    </init-param>
    <load-on-startup>0</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>action</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>