Javascript HTTP状态400所需的MultipartFile[]参数不存在

在尝试将多个文件上载到ajax请求时，我遇到以下错误。下面是日志和我的脚本中的错误。当console.log按预期打印出来时，ajax请求似乎失败了。我不知道这是什么意思

<h1>HTTP Status 400 - Required MultipartFile[] parameter 'files' is not present</h1>

配置

@Bean(name = "multipartResolver")
public CommonsMultipartResolver commonsMultipartResolver(){
    CommonsMultipartResolver commonsMultipartResolver = new CommonsMultipartResolver();
    commonsMultipartResolver.setDefaultEncoding("utf-8");
    commonsMultipartResolver.setMaxUploadSize(5000000); // 5000000 -> 5MB
    return commonsMultipartResolver;

} }

将enctype=“multipart/form data”添加到jsp中的表单标记中。

private static String UPLOADED_FOLDER = "C://temp//";

@RequestMapping(value = { "/fileUpload" }, method = RequestMethod.POST)
@ResponseBody
public String uploadFile( @RequestParam("number") String number, @RequestParam("files") MultipartFile[] files, MultipartHttpServletRequest req, HttpServletResponse res)
{       
    for (MultipartFile file : files) {
    try {
        File directory = new File(UPLOADED_FOLDER + number);
                if (! directory.exists()){
                    directory.mkdir();
                  }
            byte[] bytes = file.getBytes();
            Path path = Paths.get(UPLOADED_FOLDER + number + "//" + file.getOriginalFilename());
            Files.write(path, bytes);
            logger.info("You have successfully uploaded '" + file.getOriginalFilename() + "'");
            return("File Uploaded");


    } catch (Exception e) {
        res.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        logger.error("Failed to upload file '" + file.getOriginalFilename() + "'", e);
        return("File Not Uploaded");
    }
}
    return "redirect:/fileUpload";
}

}

@Bean(name = "multipartResolver")
public CommonsMultipartResolver commonsMultipartResolver(){
    CommonsMultipartResolver commonsMultipartResolver = new CommonsMultipartResolver();
    commonsMultipartResolver.setDefaultEncoding("utf-8");
    commonsMultipartResolver.setMaxUploadSize(5000000); // 5000000 -> 5MB
    return commonsMultipartResolver;