8. Java Code Sample: Drop-Off Upload

public void uploadFile(final TypedValue<InputStream> fileData, String filename, String fileCode , Long fileSize) throwsThruTransportException {
   String transportCode = getTransportCode();
   Preconditions.checkArgument(fileData != null,"fileData cannot be ");
   Preconditions.checkArgument(StringUtils.isNotEmpty(transportCode), "transportCode cannot be null or empty");
   Preconditions.checkArgument(StringUtils.isNotEmpty(fileCode), "fileCode cannot be null or empty");
   Preconditions.checkArgument(fileSize >= 0, "fileSize should be a non-negative integer");

   logger.debug("[uploadFile] Uploading file with transportCode %s, filename %s, fileCode %s, fileSize %d", transportCode, filename,fileCode, fileSize);

   byte[] buffer = new byte[BUFFER_SIZE]; // Use 4MB as chunk size
   String rUrl = server + "/api/TransportMgr/FlowDropOffChunk/" + transportCode + getOptionalPathPart();

   try {
           sendInitialFileInfo(rUrl, filename, fileCode, fileSize);

      logger.info("[uploadFile] Uploading file chunks to URL {}", rUrl);
      int chunkNum = 1;
      int chunkSize = DataBufferUtil.readToBuffer(fileData.getValue(), buffer);
      while (chunkSize > 0) {

         ByteArrayInputStream chunk = new ByteArrayInputStream(Arrays.copyOfRange(buffer, 0, chunkSize));

         String chunkName = fileCode + "_Chunk" + String.format("%06d", chunkNum);
         MultipartHttpEntity multiPartFormData = buildHttpContent(chunkName, chunkSize, chunk,fileData.getDataType().getMediaType().toString());

         logger.debug("[uploadFile] Uploading file chunk #%d with name: %s", chunkNum, chunkName);

         HttpRequest request = HttpRequest.builder().method(HttpConstants.Method.POST).uri(rUrl).addHeader("Authorization",buildAuthHeader()).entity(multiPartFormData).build();
         HttpResponse response = apiClient.send(request, 30000, false, null);

         logger.debug("[uploadFile] Received HTTP Response for file chunk #%d: %d %s", chunkNum, response.getStatusCode(),response.getReasonPhrase());
         validateHttpResponse(response, "uploadFile");

         chunkNum++;
         chunkSize = DataBufferUtil.readToBuffer(fileData.getValue(), buffer);
      }
      logger.info("[uploadFile] Upload of file chunks completed. Number of uploaded chunks: {}", chunkNum - 1);

      sendEOFCommand(rUrl, fileCode, fileData.getDataType().getMediaType().toString());
   } catch (IOException ex) {
      logger.error("[uploadFile]", ex);
      throw new ThruTransportException("Error Upload File: " + ex.getMessage(), MFTErrorType.UNKNOWN_CLIENT);
   }
   catch (TimeoutException ex) {
      logger.error("[uploadFile]", ex);
      throw new ThruTransportException("Error Upload File: " + ex.getMessage(), MFTErrorType.TIMEOUT);
   }
}

private void sendInitialFileInfo(String apiCallUrl, String prefix, String fileCode, long fileSize) throws IOException, TimeoutException {
   logger.info("[sendInitialFileInfo] Sending initial file information with fileCode {} to URL {}", fileCode, apiCallUrl);

   MFTFileAttributes fileInfo = new MFTFileAttributes(fileCode, prefix, fileSize);
   String json = new JSONObject(fileInfo).toString();

   logger.debug("[sendInitialFileInfo] File information in json format: %s", json);

   ByteArrayInputStream inputData = new ByteArrayInputStream(json.getBytes(StandardCharsets.UTF_8));
   MultipartHttpEntity httpEntity = buildHttpContent(fileCode + "_Chunk000000.txt", json.getBytes(StandardCharsets.UTF_8).length,inputData, "application/binary");

   HttpRequest request = HttpRe-quest.builder().method(HttpConstants.Method.POST).uri(apiCallUrl).addHeader("Authorization",buildAuthHeader()).entity(httpEntity).build();

   HttpResponse response = apiClient.send(request, 30000, false, null);
   logger.info("[sendInitialFileInfo] Received HTTP Response: {} {}", response.getStatusCode(), response.getReasonPhrase());

   validateHttpResponse(response, "sendInitialFileInfo");
}

private MultipartHttpEntity buildHttpContent(String fileName, int content-Size, ByteArrayInputStream data, String mimeType) {
   logger.debug("[buildHttpContent] Building multipart/form-data with fileName %s, contentSize %d", fileName, contentSize);

   byte[] byteArrayContent = IOUtils.toByteArray(data);
   HttpPart httpPart = new HttpPart("fileChunk", fileName, byteArrayContent, mimeType, contentSize);
       StringBuilder builder = new StringBuilder();
       builder.append("form-data");
       builder.append("; name=\"");
       builder.append("file");
       builder.append("\"");
       if (httpPart.getFileName() != null) {
           builder.append("; filename=\"");
           builder.append(fileName);
           builder.append("\"");
       }
       builder.append("; size=");
       builder.append(contentSize);

   httpPart.addHeader("ContentDisposition", builder.toString());
       return new MultipartHttpEntity(singleton(httpPart));
}

private void sendEOFCommand(String apiCallUrl, String fileCode, String mime-Type) throws IOException, TimeoutException {
   logger.info("[sendEOFCommand] Sending EOF command with fileCode {} to URL {}", fileCode, apiCallUrl);

   String eofContent = "End of file";
   byte[] data = Base64.encodeBytes(eofContent.getBytes(StandardCharsets.UTF_8), Base64.DONT_BREAK_LINES).getBytes(StandardCharsets.UTF_8);
   ByteArrayInputStream inputData = new ByteArrayInputStream(data);
   MultipartHttpEntity httpEntity = buildHttpContent("_EOF_" + file-Code, data.length , inputData, mimeType);
   HttpRequest request = HttpRe-quest.builder().method(HttpConstants.Method.POST).uri(apiCallUrl).
         addHeader("Authorization", buildAuthHeader()).entity(httpEntity).build();
   HttpResponse response = apiClient.send(request, 30000, false, null);

   logger.info("[sendEOFCommand] Received HTTP Response: {} {}", response.getStatusCode(),
         response.getReasonPhrase());

   validateHttpResponse(response, "sendEOFCommand");
}