Creating an Unattended File Transfer Application using Java

In the fast-paced technological world we live in, it's essential to streamline the transfer of files for day-to-day operations. Today, I present to you a unique and interesting project – creating an automated application for unattended file transfer using Java. This project will be done using Java's built-in libraries and will not involve any external libraries or APIs.

Firstly, let's talk about the essential features of our unattended file transfer application. This application will be a console-based program that automatically transfers files from one location to another at a pre-defined time. This feature is handy for situations where a database dump or report needs to be moved from a server to a backup location without any human intervention. Here, the user will provide the source and destination directories, the transfer schedule, and the type of files to be transferred. I am using Java's `java.nio` package because it provides a more versatile set of high-level APIs to deal with file I/O.

For the scheduling of tasks, I will be making use of Java's `java.util.Timer` and `java.util.TimerTask` classes. These classes are a utility for tasks that need to be performed at regular intervals. This is ideal for our application since the file transfer needs to occur at predetermined times. The logic for scheduling tasks can be as simple or as complex as necessary.

  Timer timer = new Timer();
  timer.scheduleAtFixedRate(new TimerTask() {
    @Override
    public void run() {
      transferFiles();
    }
  }, 0, 10000);

Here, the `transferFiles` method contains the logic for the actual transfer of files using the `java.nio` APIs. The source and destination file paths are hardcoded for simplicity, but in a real application, they could be read from a configuration file or passed as arguments from the command line.

  void transferFiles() {
    Path sourceDirectory = Paths.get("source_directory_path");
    Path destinationDirectory = Paths.get("destination_directory_path");

    try (DirectoryStream<Path> directoryStream = Files.newDirectoryStream(sourceDirectory)) {
      for (Path path : directoryStream) {
        Files.copy(path, destinationDirectory.resolve(path.getFileName()));
      }
    } catch (IOException ex) {
      ex.printStackTrace();
    }
  }

This piece of code makes use of Java's try-with-resources feature to ensure that the `DirectoryStream` is closed after we finish iterating through it. The `Files.copy` method is used to copy each file from the source to the destination directory. If the file is already present in the destination directory, an exception is thrown, which you can handle based on the specific requirements.

As we discussed, this was a simple version of the unattended file transfer application. Depending on your specific requirements, you might want to add more functionality, like transferring only certain types of files, having a log of all transferred files, or even sending an email notification post file transfer. All these requirements can be conveniently added to our base application, making it a perfect fit for the unattended tasks.

Exploring the possibilities of this unattended application lets you dive deeper into some of the powerful APIs provided by java like `java.nio`, `java.util.Timer`, and `java.util.TimerTask`. Till then, keep coding and experimenting!