APIService :

    @Multipart
    @POST("")
    Observable<SysRecordBean> postFile(@PartMap Map<String, RequestBody> map);

 代码里：

             Map<String,RequestBody> map=new HashMap<>();
                map.put("idCard",RequestBody.create(MediaType.parse("multipart/form-data"),sfz));
                map.put("name",RequestBody.create(MediaType.parse("multipart/form-data"),name));
                map.put("phone",RequestBody.create(MediaType.parse("multipart/form-data"),phone));
                map.put("pictureNumber",RequestBody.create(MediaType.parse("multipart/form-data"),String.valueOf(imgList.size)));
            //多个图片文件
                for (int i = 0; i <4 ; i++) {
                        File file=new File(imgList.get(i));
                        map.put("image"+i+"\";filename=\""+"image"+i+".jpg"
                                ,RequestBody.create(MediaType.parse("multipart/form-data"),file));
                }