How to do multiple attempts to upload using SFTP protocol?

Question

In case of file upload fails then how to do multiple attempts while doing SFTP by using JSCH API? How to ensure file is uploaded successfully? How to create thread-safe file upload utility?

Answer 1

Create a common static utility method which can be invoked from the external class. This method has a map argument to persist the values of sFTPUser, sFTPHost, sFTPPort, sFTPPwd, destinationLocation and uploadedFileName :

public static void doSFTP(Map<String, String> ftpParameters) {

        if (ftpParameters.get("ID_NAME").equals(
                NAPSCommonConstants.MFT_NAPSGPCS_INTF)) {
            // do sftp for NAPS GPCS Interface.
            uploadUsingSFTP(ftpParameters);
        }
    }

Use synchronized method to ensure thread safety:

private static synchronized void uploadUsingSFTP(
            Map<String, String> ftpPrameterList) {
        new SFTPUtility().uploadFileMFT(ftpPrameterList.get("sFTPUser"),
                ftpPrameterList.get("sFTPHost"), new Integer(ftpPrameterList
                        .get("sFTPPort")), ftpPrameterList.get("sFTPPwd"),
                ftpPrameterList.get("sourceLocation"), ftpPrameterList
                        .get("destinationLocation"), ftpPrameterList
                        .get("uploadedFileName"));
    }

Responsible method to upload files using SFTP with 5 attempts:

private void uploadFileMFT(String sFTPUser, String sFTPHost, int sFTPPort,
            String sFTPPwd, String sourceLocation, String destinationLocation,
            String uploadedFileName) {

        LOG.info("Inside uploadFileMFT to upload and verify the file.");

        JSch jsch = new JSch();
        Vector<String> fileList = null;

        /** 5 re-attempt logic to get session */
        int attempts = 0;
        boolean successfulConnect;
        do {
            try {
                successfulConnect = true;
                session = jsch.getSession(sFTPUser, sFTPHost, sFTPPort);
                LOG.debug("session connected ...");

                session.setPassword(sFTPPwd);
                Properties config = new Properties();
                config.put("StrictHostKeyChecking", "no");
                session.setConfig(config);

                session.connect();
                LOG.debug("Sftp Session connected ...");

                channel = session.openChannel("sftp");
                LOG.debug("Sftp Channel opened ...");

                channelSftp = (ChannelSftp) channel;
                channelSftp.connect();
                LOG.info(" Sftp channel opened and connected ...");

                channelSftp.put(sourceLocation, destinationLocation);

                fileList = channelSftp.ls(destinationLocation);

            } catch (JSchException e) {
                ++attempts;
                successfulConnect = false;
                LOG.error(e);
            } catch (SftpException e) {
                ++attempts;
                successfulConnect = false;
                LOG.error(e);
            } finally {
                if (null != channelSftp) {
                    channelSftp.exit();
                    LOG.debug(" sftp Channel exited.");
                }

                if (null != channel) {
                    channel.disconnect();
                    LOG.debug(" Channel disconnected.");
                }

                if (null != session) {
                    session.disconnect();
                    LOG.debug(" Host Session disconnected.");
                }
            }
        } while (attempts < 5 && successfulConnect == false);

        fileUploadValidation(fileList, uploadedFileName);

        LOG.info("Exiting from method - uploadFileMFT ...");
    }

Finally uploaded file can be validated:

private void fileUploadValidation (Vector<String> fileList, String uploadedFileName){
        boolean isFileExistis = false;
        Object[] objArr = fileList.toArray();
        for (int i = 0; i < objArr.length; i++) {
            String fileName = objArr[i].toString();
            isFileExistis = fileName.contains(uploadedFileName);
            if (isFileExistis) {
                LOG.info("Uploaded file '" + uploadedFileName + "' was transferred successfull ...");
                break;
            }else if(i >= objArr.length){
                LOG.info("Uploaded file '" + uploadedFileName + "' was failed to transfer ...");
            }

        }
    }