I´m trying to watch a specific folder for changes, and then if any addition/edition/removal happens inside of it, I need to get the change type of all files in that folder and its subfolders. I'm using WatchService
for this but it only watches a single path, it doesn't handle subfolders.
Here's my approach:
try {
WatchService watchService = pathToWatch.getFileSystem().newWatchService();
pathToWatch.register(watchService, StandardWatchEventKinds.ENTRY_CREATE,
StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_DELETE);
// loop forever to watch directory
while (true) {
WatchKey watchKey;
watchKey = watchService.take(); // This call is blocking until events are present
// Create the list of path files
ArrayList<String> filesLog = new ArrayList<String>();
if(pathToWatch.toFile().exists()) {
File fList[] = pathToWatch.toFile().listFiles();
for (int i = 0; i < fList.length; i++) {
filesLog.add(fList[i].getName());
}
}
// Poll for file system events on the WatchKey
for (final WatchEvent<?> event : watchKey.pollEvents()) {
printEvent(event);
}
// Save the log
saveLog(filesLog);
if(!watchKey.reset()) {
System.out.println("Path deleted");
watchKey.cancel();
watchService.close();
break;
}
}
} catch (InterruptedException ex) {
System.out.println("Directory Watcher Thread interrupted");
return;
} catch (IOException ex) {
ex.printStackTrace(); // Loggin framework
return;
}
Like I said before, I'm getting the log only for the files in the selected path, and I want to watch all folders and subfolders files, something like:
Example 1:
FileA (Created)
FileB
FileC
FolderA FileE
FolderA FolderB FileF
Example 2:
FileA
FileB (Modified)
FileC
FolderA FileE
FolderA FolderB FileF
Is there any better solution?
A WatchService
only watches the Path
s you register. It does not go through those paths recursively.
Given /Root
as a registered path
/Root
/Folder1
/Folder2
/Folder3
If there is a change in Folder3
, it won't catch it.
You can register the directory paths recursively yourself with
private void registerRecursive(final Path root) throws IOException {
// register all subfolders
Files.walkFileTree(root, new SimpleFileVisitor<Path>() {
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
dir.register(watchService, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
return FileVisitResult.CONTINUE;
}
});
}
Now the WatchService
will notify all changes in all subfolders of Path root
, ie. the Path
argument you pass.