private static final MediaType MEDIA_TYPE_PNG = MediaType.parse("image/png");

/**
   * 上傳多張圖片及參數(shù)
   * @param reqUrl URL地址
   * @param params 參數(shù)
   * @param pic_key 上傳圖片的關(guān)鍵字
   * @param paths 圖片路徑
   */
  public Observable<String> sendMultipart(String reqUrl,Map<String, String> params,String pic_key, List<File> files){
    return Observable.create(new Observable.OnSubscribe<String>(){

      @Override
      public void call(Subscriber<? super String> subscriber) {
        MultipartBody.Builder multipartBodyBuilder = new MultipartBody.Builder();
        multipartBodyBuilder.setType(MultipartBody.FORM);
        //遍歷map中所有參數(shù)到builder
        if (params != null){
          for (String key : params.keySet()) {
            multipartBodyBuilder.addFormDataPart(key, params.get(key));
          }
        }
        //遍歷paths中所有圖片絕對(duì)路徑到builder，并約定key如“upload”作為后臺(tái)接受多張圖片的key
        if (files != null){
          for (File file : files) {
            multipartBodyBuilder.addFormDataPart(pic_key, file.getName(), RequestBody.create(MEDIA_TYPE_PNG, file));
          }
        }
        //構(gòu)建請(qǐng)求體
        RequestBody requestBody = multipartBodyBuilder.build();

        Request.Builder RequestBuilder = new Request.Builder();
        RequestBuilder.url(reqUrl);// 添加URL地址
        RequestBuilder.post(requestBody);
        Request request = RequestBuilder.build();
        mOkHttpClient.newCall(request).enqueue(new Callback() {
          @Override
          public void onFailure(Call call, IOException e) {
            subscriber.onError(e);
            subscriber.onCompleted();
            call.cancel();
          }

          @Override
          public void onResponse(Call call, Response response) throws IOException {
            String str = response.body().string();
            subscriber.onNext(str);
            subscriber.onCompleted();
            call.cancel();
          }
        });
      }
    });
  } 

OkHttp3Utils.getInstance().sendMultipart(Constants.URL.URL_ADD_NOTICE, mMap, "appendix", mImageList)
        .observeOn(AndroidSchedulers.mainThread())
        .subscribeOn(Schedulers.newThread())
        .subscribe(new Subscriber<String>() {
          @Override
          public void onCompleted() {

          }

          @Override
          public void onError(Throwable throwable) {
            LogUtil.i(TAG, "throwable:" + throwable.toString());
          }

          @Override
          public void onNext(String s) {
            
            LogUtil.i(TAG, "s:" + s);
          }
        });