How to convert from org.apache.commons.net.ftp.FTPFile to String?

Question

I'm retrieving files list from FTPClient using ftpClient.listFiles(); and it returns an array with correct file names and appropriate quantity.

I'm trying to read content from files, but only ftpClient.retrieveFileStream(fileName) is available for that purpose. And it somehow breaks after reading the first file and returns null.

Is there a way to convert FTPFile directly into String?

    ftp.connect();
            ftp.changeWorkingDirectoryToFrom();

            List<String> idsList = new ArrayList<String>();

            List<String> names = ftp.listFileNames();
            for (String fileName : names) {
                String content = fromFTPFileToString(fileName);
                Matcher matcher = FILES_PATTERN.matcher(content);
                String id = extractId(content);

                if (matcher.find()) {
                    boolean duplicate = idsList.contains(id);
                    LOG.info("MATCHED: " + fileName);
                    if (!duplicate) {
                        ftp.moveFileFromTo(fileName);
                        idsList.add(id);
                    } else {
                        LOG.info("DUPLICATE: " + fileName);
                        duplicated++;
                        ftp.deleteFileOnFromFtp(fileName);
                    }
                }
                processed++;
            }
            ftp.disconnect();

    private String fromFTPFileToString(String fileName) {
            String content = "";
            try {
                InputStream is = ftp.readContentFromFTPFile(fileName);
                StringWriter writer = new StringWriter();
                IOUtils.copy(is, writer, ENCODING);
                content = writer.toString();

                IOUtils.closeQuietly(is);
                IOUtils.closeQuietly(writer);
            } catch (Exception ex) {
                LOG.error(ex);
            }

            return content;
        }

void deleteFileOnFromFtp(String fileName) {
        changeWorkingDirectory(properties.getProperty(PropertiesType.FOLDER_FROM.toString()));
        deleteFile(fileName);
    }

    InputStream readContentFromFTPFile(String fileName) {
        changeWorkingDirectory(properties.getProperty(PropertiesType.FOLDER_FROM.toString()));
        InputStream inputStream = null;
        try {
            inputStream = ftpClient.retrieveFileStream(fileName);
        } catch (IOException ex) {
            LOG.error("Unable to extract content from file:" + O_Q + fileName + C_Q);
        }
        return inputStream;
    }

    void moveFileFromTo(String fileName) {
        String from = FORWARD_SLASH + properties.getProperty(PropertiesType.FOLDER_FROM.toString()) + FORWARD_SLASH + fileName;
        String to = FORWARD_SLASH + properties.getProperty(PropertiesType.FOLDER_TO.toString()) + FORWARD_SLASH + fileName;

        try {
            ftpClient.rename(from, to);
        } catch (IOException ex) {
            LOG.error("Unable to move file file from:" + O_Q + from + C_Q + " to: " + O_Q + to + C_Q);
            throw new RuntimeException(ex.getCause());
        }
    }

Answer 1

3 Hints

1) You can use retrieveFile

And use a ByteArrayOutputStream as the 2nd parameter. To get a String from it simply "new String(baos.toByteArray(),[The Charset you used]);"

2) Check for ftpClient.completePendingCommand();

If some commands are still pending

3) I had once a similar issue setting ftp.enterLocalPassiveMode() helped