struts深入原理之RequestProcessor与xml

和配置文件相对应的代码（struts1） 

public void process(HttpServletRequest request, HttpServletResponse response)
        throws IOException, ServletException {
        // Wrap multipart requests with a special wrapper
        request = processMultipart(request);

        // Identify the path component we will use to select a mapping
        String path = processPath(request, response);

        if (path == null) {
            return;
        }

        if (log.isDebugEnabled()) {
            log.debug("Processing a '" + request.getMethod() + "' for path '"
                + path + "'");
        }

        // Select a Locale for the current user if requested
        processLocale(request, response);

        // Set the content type and no-caching headers if requested
        processContent(request, response);
        processNoCache(request, response);

        // General purpose preprocessing hook
        if (!processPreprocess(request, response)) {
            return;
        }

        this.processCachedMessages(request, response);

        // Identify the mapping for this request
        ActionMapping mapping = processMapping(request, response, path);

        if (mapping == null) {
            return;
        }

        // Check for any role required to perform this action
        if (!processRoles(request, response, mapping)) {
            return;
        }

        // Process any ActionForm bean related to this request
        ActionForm form = processActionForm(request, response, mapping);

        processPopulate(request, response, form, mapping);

        // Validate any fields of the ActionForm bean, if applicable
        try {
            if (!processValidate(request, response, form, mapping)) {
                return;
            }
        } catch (InvalidCancelException e) {
            ActionForward forward = processException(request, response, e, form, mapping);
            processForwardConfig(request, response, forward);
            return;
        } catch (IOException e) {
            throw e;
        } catch (ServletException e) {
            throw e;
        }

        // Process a forward or include specified by this mapping
        if (!processForward(request, response, mapping)) {
            return;
        }

        if (!processInclude(request, response, mapping)) {
            return;
        }

        // Create or acquire the Action instance to process this request
        Action action = processActionCreate(request, response, mapping);

        if (action == null) {
            return;
        }

        // Call the Action instance itself
        ActionForward forward =
            processActionPerform(request, response, action, form, mapping);

        // Process the returned ActionForward instance
        processForwardConfig(request, response, forward);
    }