How to monitor a folder for changes in java?

Question

I have the below code for monitoring a folder for any changes in java:

    public class FolderWatcher
    {
    // public List events = new ArrayLis         


        

Answer 1

in my case, this code was successfull:

try {
    Path rootFolder = Paths.get(ctxProperties.getProperty("rootFolder"));
    WatchService watcher = rootFolder.getFileSystem().newWatchService();
    rootFolder.register(watcher, StandardWatchEventKinds.ENTRY_CREATE);
    while (true) {
        WatchKey watchKey = watcher.take();
        if (watchKey != null) {
            for (WatchEvent event : watchKey.pollEvents()) {
                if (StandardWatchEventKinds.ENTRY_CREATE.equals(event.kind())) {
                    String fileName = rootFolder.toString() + "/" + event.context().toString();
                    String messageStr = convertFileToString(fileName);
                    if (messageStr != null) {
                        try {
                            sendMessage(jmsPublisher, messageStr, getJmsProperties());
                            moveMessageToProcessedDirectory(fileName, ctxProperties.getProperty("successFolder"), ".ok");
                            LOGGER.info("JMS message successfully sent");
    sleep(Long.parseLong(ctxProperties.getProperty("sleepBetweenMsgMse")));
                        } catch (Exception e) {
                            moveMessageToProcessedDirectory(fileName, ctxProperties.getProperty("errorFolder"), ".nok");
                        }
                    } else {
                        LOGGER.error("ERROR: error parsing file content to string with file: " + fileName);
                        moveMessageToProcessedDirectory(fileName, ctxProperties.getProperty("errorFolder"), ".nok");
                    }
                }
            }
            boolean valid = watchKey.reset();
            if (!valid) {
                LOGGER.error("ERROR: the watcher is no longer valid, the directory is inaccessible");
                break;
            }
        } else {
            LOGGER.error("ERROR: the watcher is null or not watchable");
            break;
        }
    }
} catch (InterruptedException interruptedException) {
    LOGGER.error("InterruptedException: thread got interrupted",interruptedException);
} catch (Exception exception) {
    LOGGER.error("Exception: " + exception.getMessage(), exception);
}