how to get changes in files and subfolders of a main folder?

Question

I am trying to handle the changes in a file or in a subfolder of a folder and then upload them FTP (like a syncronized folder) but I have no idea of how to do it.. anyone could give me clues or where to find/lear for make it? Id rather do it in Java.

Thanks!!

Answer 1

Watch for Changes in a Directory

Excerpt from this tutorial :

Creating a Watch Service and Registering for Events

The first step is to create a new WatchService by using the newWatchService method in the FileSystem class, as follows:

WatchService watcher = FileSystems.getDefault().newWatchService();

Next, register one or more objects with the watch service. Any object that implements the Watchable interface can be registered. The Path class implements the Watchable interface, so each directory to be monitored is registered as a Path object.

As with any Watchable, the Path class implements two register methods. This page uses the two-argument version, register(WatchService, WatchEvent.Kind...). (The three-argument version takes a WatchEvent.Modifier, which is not currently implemented.)

When registering an object with the watch service, you specify the types of events that you want to monitor. The supported StandardWatchEventKinds event types follow:

ENTRY_CREATE – A directory entry is created.
ENTRY_DELETE – A directory entry is deleted.
ENTRY_MODIFY – A directory entry is modified.
OVERFLOW – Indicates that events might have been lost or discarded. You do not have to register for the OVERFLOW event to receive it.

The following code snippet shows how to register a Path instance for all three event types:

import static java.nio.file.StandardWatchEventKinds.*;

Path dir = ...;
try {
    WatchKey key = dir.register(watcher,
                           ENTRY_CREATE,
                           ENTRY_DELETE,
                           ENTRY_MODIFY);
} catch (IOException x) {
    System.err.println(x);