How can I receive Windows filesystem events in Java?

Question

I need to know when a new file appears in a directory. Obviously, I could poll the file system periodically, but that has all the normal downsides of polling mechanisms.

I know that windows supports file system events, and this project is already constrained to the Windows platform by other requirements.

Does anyone have experience receiving Windows filesystem events inside a JVM? If so what are the best practices, patterns, and/or libraries you have used?

A quick google turns up this library. Does anyone have experience with it (or any other) that they'd be willing to share?

Answer 1

I think this is one of the key features of Java 7 when it is more available. Example code from Sun's blog on Java 7:

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

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

Answer 2

For Java 6 or older use JNA's com.sun.jna.platform.win32.FileMonitor.