如何获得正确的实体内容长度以显示进度对话框中的进度？

Question

我想在活动中通过AsyncTask使用Android MultiPart Entity上传多个图像文件。当我尝试上传单个图像文件时，进度对话框显示正确的进度，一旦达到100％的进度，对话框就会解除并执行其他任务。但是，当我尝试上传多个图像文件时，它显示100％的进度，并且进度对话框一直停留，直到其他图像文件上传到服务器。我使用for循环将多个图像文件添加到实体。但是当我试图获得内容长度时，我似乎得到了错误的价值。

@SuppressWarnings("deprecation")
private class UploadAttachments extends AsyncTask<Void, Integer, String> {
    ProgressDialog pDialog;
    long totalSize = 0;
    int statusCode;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(RegistrationActivity.this);
        pDialog.setMessage(getString(R.string.label_upload_attachments));
        pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        pDialog.setMax(mFilePaths.size());
        pDialog.setCancelable(false);
        pDialog.show();
    }

    @Override
    protected void onProgressUpdate(Integer... progress) {
        pDialog.setProgress(progress[0]);
    }

    @Override
    protected String doInBackground(Void... params) {
        return uploadFile();
    }

    @SuppressWarnings("deprecation")
    private String uploadFile() {
        String responseString;

        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(Network.URL_UPLOAD);

        try {
            AndroidMultiPartEntity entity = new AndroidMultiPartEntity(
                    new AndroidMultiPartEntity.ProgressListener() {

                        @Override
                        public void transferred(long num) {
                            publishProgress((int) ((num / (float) totalSize) * 100));
                        }
                    });

            for (int i = 0; i < mFilePaths.size(); i++) {
                entity.addPart("image" + i, new FileBody(new File(mFilePaths.get(i))));
                mPrefix += 1;
                entity.addPart("prefix" + i, new StringBody(String.valueOf(mPrefix)));
            }

            totalSize = entity.getContentLength();
            entity.addPart("count", new StringBody(String.valueOf(mFilePaths.size())));
            httppost.setEntity(entity);

            HttpResponse response = httpclient.execute(httppost);

            statusCode = response.getStatusLine().getStatusCode();
            if (statusCode == 200) {
                responseString = getString(R.string.label_upload_successful);
            } else {
                responseString = getString(R.string.error_network_error);
            }
        } catch (IOException e) {
            responseString = getString(R.string.error_network_error);
        }

        return responseString;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        pDialog.dismiss();

        if (mToast != null) mToast.cancel();

        mToast = makeText(getApplicationContext(), result, Toast.LENGTH_SHORT);
        mToast.show();

        mPreferences.clearRegDetails();

        Intent intent = new Intent(RegistrationActivity.this, MainActivity.class);
        startActivity(intent);
    }
}

请看一下。请帮帮我！感谢。