Retrofit 多图片上传，以及其他资源上传

        Map<String, RequestBody> params = new HashMap<>();
        RequestBody a= RequestBody.create(MediaType.parse("multipart/form-data"),  "");
        params.put("123", a);
//上传多张图片
         for (int i = 0; i < datas.size(); i++) {

            File file = new File((String) images.get(i).get("path"));
            RequestBody imgFile = RequestBody.create(MediaType.parse("image/jpeg"), file);
            MultipartBody.Part requestImgPart = MultipartBody.Part.createFormData("Image"+i, file.getName(), imgFile);
            params.add(requestImgPart);
        }

    //上传Json

 String json = new Gson().toJson(bean);
        RequestBody body = RequestBody.create(okhttp3.MediaType.parse("application/json; charset=utf-8"), json);

@POST("URL/Create")
    @Multipart
    Call<BaseCallBack<List<ListCallBack<Bean>>>> postCreateBean(@Part("JsonData") RequestBody requestbody,

 @Part List<MultipartBody.Part> request_img_part);