springmvc从request对象里面获取上传文件对象

    public MultipartFile getFileInReq(HttpServletRequest request, String paramName) throws UnsupportedEncodingException {
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(request.getSession().getServletContext());
        if (multipartResolver.isMultipart(request)) {
            request.setCharacterEncoding("utf-8");
            List files = ((MultipartHttpServletRequest) request).getFiles(paramName);
            return files.size() > 0 ? files.get(0) : null;
        }
        return null;
    }