使用 Post/Redirect/Get 模式保留模型状态

目前我正在尝试使用 Spring MVC 3.1 实现 Post/Redirect/Get 模式。保存和恢复模型数据+验证错误的正确方法是什么？我知道我可以在 POST 方法中使用 RedirectAttributes 保留模型和 BindingResult。但是，在 GET 方法中从闪存范围恢复它们的正确方法是什么？

我已完成以下 POST 操作：

    @RequestMapping(value = "/user/create", method = RequestMethod.POST)
public String doCreate(@ModelAttribute("user") @Valid User user, BindingResult result, RedirectAttributes rA){

    if(result.hasErrors()){
        rA.addFlashAttribute("result", result);
        rA.addFlashAttribute("user", user);

        return "redirect:/user";
    }

    return "redirect:/user/success";
}

获取用户创建表单的步骤如下：

    @RequestMapping(value = "/user", method = RequestMethod.GET)
public ModelAndView showUserForm(@ModelAttribute("user") User user, ModelAndView model){

    model.addObject("user", user);
    model.setViewName("userForm");

    return model;
}

这使我能够在发生错误时保留给定的用户数据。但是恢复错误的正确方法是什么？（BindingResult）我想用 spring 表单标签在表单中显示它们：

<form:errors path="*" />

另外，如何从 get 方法访问 flash 范围会很有趣？

public class BindingHandlerInterceptor extends HandlerInterceptorAdapter {

    public static final String BINDING_RESULT_FLUSH_ATTRIBUTE_KEY = BindingHandlerInterceptor.class.getName() + ".flashBindingResult";

    private static final String METHOD_GET = "GET";
    private static final String METHOD_POST = "POST";


    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {


        if(METHOD_POST.equals(request.getMethod())) {

            BindingResult bindingResult = getBindingResult(modelAndView);

            FlashMap outFlash = RequestContextUtils.getOutputFlashMap(request);

            if(bindingResult == null || ! bindingResult.hasErrors() || outFlash == null ) {
                return;
            }

            outFlash.put(BINDING_RESULT_FLUSH_ATTRIBUTE_KEY, bindingResult);

        }

        Map<String, ?> inFlash = RequestContextUtils.getInputFlashMap(request);

        if(METHOD_GET.equals(request.getMethod()) && inFlash != null && inFlash.containsKey(BINDING_RESULT_FLUSH_ATTRIBUTE_KEY)) {

            BindingResult flashBindingResult = (BindingResult)inFlash.get(BINDING_RESULT_FLUSH_ATTRIBUTE_KEY);

            if(flashBindingResult != null) {

                BindingResult bindingResult = getBindingResult(modelAndView);

                if(bindingResult == null) {
                    return;
                }

                bindingResult.addAllErrors(flashBindingResult);

            }

        }

    }

    public static BindingResult getBindingResult(ModelAndView modelAndView) {

        if(modelAndView == null) {
            return null;
        }

        for (Entry<String,?> key : modelAndView.getModel().entrySet()) {
            if(key.getKey().startsWith(BindingResult.MODEL_KEY_PREFIX)) {
                return (BindingResult)key.getValue();
            }
        }

        return null;
    }


}