我如何计算HttpURLConnection已经向服务器发送了多少数据？

Question

我向服务器发送了byte[]。我可以计算我要发送的byte[]大小，但是如何获得已发送的byte[]大小？我希望实现它，以便向用户显示％{。}}中的progressBar。

这是我的代码：

public static JSONObject sentJsonToServer(final URL url, final byte[] data, final String newValue) {

    ExecutorService ex = Executors.newCachedThreadPool();
    Future<JSONObject> objectFuture = ex.submit(new Callable<JSONObject>() {
        @Override
        public JSONObject call() throws Exception {

            BufferedOutputStream bos = null;
            HttpURLConnection urlConnection = null;

            try {

                urlConnection = (HttpURLConnection) url.openConnection();
                urlConnection.setRequestProperty("Content-Type", newValue);
                urlConnection.setRequestMethod("POST");
                urlConnection.setDoInput(true);
                urlConnection.setDoOutput(true);
                urlConnection.connect();
                bos = new BufferedOutputStream(urlConnection.getOutputStream());
                bos.write(data);
                bos.flush();

            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    if (bos != null) {
                        bos.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

//              returns POST request
            if (urlConnection != null) {
                return getJSONFromUrl(urlConnection);
            } else {
                throw new NullPointerException();
            }
        }
    });

    JSONObject responseJson = null;

    try {
        responseJson = objectFuture.get();
    } catch (InterruptedException | ExecutionException | NullPointerException e) {
        e.printStackTrace();
    }
    System.out.println("LAST JSOOOOOOOOOOON!!!!!!!!!!!!!!! " + responseJson);

    return responseJson;
}

我尝试实现类似ProgressListener()的smth但没有成功（

我是如何做到的？