參考如下方式

@Multipart
@POST(NRConfig.UPDATE_FILES)
Call<Result<UpdateFilesEntity>> updateOneFile(@PartMap Map<String,RequestBody> data,@Part("pic") RequestBody description,@Part MultipartBody.Part file);

使用@Multipart註解，引數通過@PartMap形式上傳，注意，這裡一定要用Map<String,RequestBody>這樣的格式，

也只能用RequestBody形式，本身retrofit是僅支援兩種形式的String型別，這裡的不在其中，故此不支援直接使用
 

String型別，必須轉成RequestBody形式，附上轉型方法

public static RequestBody toRequestBody(String value) {
    RequestBody requestBody = RequestBody.create(MediaType.parse("text/plain"), value);
    return requestBody;
}

最後再給上完整的程式碼

/**
 * @param callback
 * @return
 */
public static Call updateOneFile(Map<String,RequestBody> type, File file, final ResultCallback<Result<UpdateFilesEntity>> callback) {

    if (callback == null) throw new NullPointerException("callback == null");
    NRService mService = ServiceFactory.createNewService(NRService.class);

    RequestBody reqFile = RequestBody.create(MediaType.parse("image/*"), file);
    MultipartBody.Part body = MultipartBody.Part.createFormData("file", file.getName(), reqFile);

    String descriptionString = "image";
    RequestBody description = RequestBody.create(MediaType.parse("multipart/form-data"), descriptionString);

    Call<Result<UpdateFilesEntity>> call = mService.updateOneFile(type, description, body);
    Callback<Result<UpdateFilesEntity>> cbk = new Callback<Result<UpdateFilesEntity>>() {

        @Override
        public void onResponse(Call<Result<UpdateFilesEntity>> call, Response<Result<UpdateFilesEntity>> response) {
            Result.onResponse(response, callback);
        }

        @Override
        public void onFailure(Call<Result<UpdateFilesEntity>> call, Throwable t) {
            Result.onFailure(t, callback);
        }
    };
    call.enqueue(cbk);
    return call;
}
 

參考地址：http://blog.csdn.net/honghailiang888/article/details/62884231

有興趣的可以直接閱讀原文，我這裡只是撿重點