//圖片集合
List<String> imgs = new ArrayList<>();
//壓縮后的圖片路徑集合
List<String> tmpImgs = new ArrayList<>();

Handler mHandler = new Handler() {
  @Override
  public void handleMessage(Message msg) {
    super.handleMessage(msg);
    //TODO 收到消息后調(diào)用網(wǎng)絡(luò)請(qǐng)求上傳
  }
};

public void compressImages() {
  new Thread(new Runnable() {
    @Override
    public void run() {
      for (String path : imgs) {
        //TODO 調(diào)用壓縮圖片的方法，壓縮后保存在一個(gè)臨時(shí)文件夾中
        tmpImgs.add("壓縮后路徑");
      }
      mHandler.sendEmptyMessage(0);
    }
  }).start();
}

@Multipart
@POST("your address")
Observable<String> uploadImgs(@PartMap Map<String, RequestBody> map,                     @Part("imgs") MultipartBody body);

//先定義一個(gè)請(qǐng)求接口，除了圖片可能還有其他一些參數(shù)需要上傳，所以還定義了個(gè)map。接下來(lái)開(kāi)始正文：

public void upload() {
  final Map<String, RequestBody> map = new HashMap<>();
  map.put("userId", RequestBody.create(MediaType.parse("form-data"),"1");
  final MultipartBody.Builder builder = new MultipartBody.Builder();
  Observable.from(imgs)
      .map(new Func1<String, String>() {
        @Override
        public String call(String path) {
          //調(diào)用圖片壓縮，返回壓縮后路徑tmp_path
          //注意，F(xiàn)iledata是后臺(tái)給你的對(duì)應(yīng)的字段
          builder.addFormDataPart("Filedata", "avatar.png", RequestBody.create(MultipartBody.FORM, new File(tmp_path)));
          return path;
        }
      }).last()
      .flatMap(new Func1<String, Observable<String>>() {
        @Override
        public Observable<String> call(String path) {
          return apiService.uploadImgs(map, builder.build());
        }
      })
      .subscribeOn(Schedulers.io())
      .observeOn(AndroidSchedulers.mainThread())
      .subscribe(new Subscriber<String>() {
        @Override
        public void onCompleted() {
        }
        @Override
        public void onError(Throwable e) {
          //錯(cuò)誤處理
        }
        @Override
        public void onNext(String res) {
          //成功后處理
        }
      });
}