问使用AsyncTask通过ftp4j上载文件时，进度栏不会更新

EN

private class UploadFile extends AsyncTask<String, Integer, Boolean> {
    @Override
    protected Boolean doInBackground(String... params) {
        FTPClient client = null;
        String filePath = params[0];
        try {
            // Get the FTP Connection from the Utility class
            client = FTPUtility.connect(ipAddress, userName, password);
            //if directory is not there, create it.
            try {
                client.changeDirectory(params[1]);
            } catch(Exception e) {
                client.createDirectory(params[1]);
                client.changeDirectory(params[1]);
            }

            if (client != null) {
                try {
                    // Define the File with complete path to be uploaded
                    File fileUpload = new File(filePath);

                    fileSize= fileUpload.length();
                    Log.d("FTPSync", "File Size: "+fileSize);
                    Log.d("FTPSync", "Uploading the " + filePath
                            + " to Remote Machine");

                    // Upload the file
                    client.upload(fileUpload, new FTPDataTransferListener() {
                        @Override
                        public void started() {
                            // Transfer started
                            Log.d("FTP","TRANSFER-STATUS: File transfer started...");
                        }
                        @Override
                        public void transferred(int length) {
                            int progress = (length*100)/((int)fileSize);
                            publishProgress(progress);
                            Log.d("FTP","Progress: "+progress);
                        }
                        @Override
                        public void completed() {           
                            Log.d("FTP","TRANSFER-STATUS: File transfer completed...");
                        }
                        @Override
                        public void aborted() {
                            // Transfer aborted
                            Log.d("FTP","TRANSFER-STATUS: File transfer aborted...");
                        }
                        @Override
                        public void failed() {
                            // Transfer failed
                            Log.d("FTP","TRANSFER-STATUS: File transfer failed...");

                        }
                    });
                    Log.d("FTPSync", "Successfully Uploaded the "
                            + filePath + " File to Remote Machine");

                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        finally {
            if (client != null) {
                try {
                    client.disconnect(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }

        return null;
    }

    @Override
    protected void onPostExecute(Boolean result) {
        pDialog.dismiss();
        Toast.makeText(context, "Operation Completed", Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onPreExecute() {
        pDialog = new ProgressDialog(context);
        pDialog.setMessage(message);
        pDialog.setIndeterminate(true);
        pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        pDialog.setCancelable(false);
        pDialog.show();
    }

    @Override
    protected void onProgressUpdate(Integer... values) {
        pDialog.setProgress(values[0]);
    }
}
private static class FTPUtility {
    public static FTPClient connect(String ipAddress, String userName,
            String password) {
        FTPClient client = new FTPClient();
        Log.d("FTP","Connecting to " + ipAddress);
        try {
            client.setType(FTPClient.TYPE_BINARY);
            client.connect(ipAddress);
            client.login(userName, password);
            return client;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}