ajax传递给springmvc数据中包含token，如何在interceptor中取出token数据

Question

我试图实现一个防止表单重复提交的功能，可是我不知道如何在Interceptor中获取我在ajax中提交的token数据。我的代码基本如下：
TokenInterceptor.java

public class TokenInterceptor extends HandlerInterceptorAdapter {
    private static final Logger logger = Logger.getLogger(TokenInterceptor.class);
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if (handler instanceof HandlerMethod) {
            HandlerMethod handlerMethod = (HandlerMethod) handler;
            Method method = handlerMethod.getMethod();
            Token annotation = method.getAnnotation(Token.class);

            if (annotation != null) {
                boolean needSaveSession = annotation.save();
                if (needSaveSession) {
                    request.getSession(false).setAttribute(SessionProperties.TOKEN, UUIDGenerator.generateUUID());
                }
                boolean needRemoveSession = annotation.remove();
                if (needRemoveSession) {
                    if (isRepeatSubmit(request, SessionProperties.TOKEN)) {
                        return false;
                    }
                    request.getSession(false).removeAttribute(SessionProperties.TOKEN);
                }
            }
            return true;
        } else {
            return super.preHandle(request, response, handler);
        }
    }

    private boolean isRepeatSubmit(HttpServletRequest request, String tokenName) {
        String serverToken = (String) request.getSession(false).getAttribute(tokenName);

        if (serverToken == null) {
            return true;
        }
        String clientToken = request.getParameter(tokenName);


        if (clientToken == null) {
            return true;
        }

        if (!serverToken.equals(clientToken)) {
            return true;
        }
        return false;
    }
}

ajax数据

    var product = {
        'token' : token,
        'name' : name,
        'shortId' : shortId,
        'serializedId' : serializedId,
        'categoryId' : categoryId,
        'comment' : comment,
        'productSpecBeans' : specs==null ? [] : specs,
        'tags' : tags==null ? [] : tags,
    }

服务器端controller

    @Token(save = true)
    @RequestMapping(value = "add", method = RequestMethod.GET)
    public ModelAndView add( HttpServletRequest servletRequest){
        ModelMap modelMap = new ModelMap();
        ProductBean productBean = new ProductBean();
        modelMap.addAttribute(SessionProperties.PRODUCT_ADD_BEAN, productBean);
        return new ModelAndView("product_add", modelMap);
    }

Token标签

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Token {

    boolean save() default false;

    boolean remove() default false;

}

这里的interceptor参考了网上的代码设计，但是网上一般采用form来提交表单，如果采用ajax的data如何提取token呢？