Java File Directory Watcher
As you saw in last example of Java Directory watcher below is another example of Java File Directory watcher:
- JavaDirectoryChangeListener.java:
package com.javahonk;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchEvent.Kind;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
public class JavaDirectoryChangeListener implements Runnable {
private static Path directoryPath;
public static void main(String[] args) {
directoryPath = FileSystems.getDefault().getPath("C:\\LAS\\JavaHonk\\New folder");
Thread thread = new Thread(new JavaDirectoryChangeListener());
thread.start();
}
@Override
public void run() {
try {
WatchService watchService = directoryPath.getFileSystem().newWatchService();
directoryPath.register(watchService, StandardWatchEventKinds.ENTRY_CREATE,
StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_DELETE);
//Start infinite loop to watch changes on the directory
while (true) {
WatchKey watchKey = watchService.take();
// poll for file system events on the WatchKey
for (final WatchEvent<?> event : watchKey.pollEvents()) {
//Calling method
takeActionOnChangeEvent(event);
}
//Break out of the loop if watch directory got deleted
if (!watchKey.reset()) {
watchKey.cancel();
watchService.close();
System.out.println("Watch directory got deleted. Stop watching it.");
//Break out from the loop
break;
}
}
} catch (InterruptedException interruptedException) {
System.out.println("Thread got interrupted:"+interruptedException);
return;
} catch (Exception exception) {
exception.printStackTrace();
return;
}
}
private void takeActionOnChangeEvent(WatchEvent<?> event) {
Kind<?> kind = event.kind();
if (kind.equals(StandardWatchEventKinds.ENTRY_CREATE)) {
Path entryCreated = (Path) event.context();
System.out.println("New entry created:" + entryCreated);
} else if (kind.equals(StandardWatchEventKinds.ENTRY_DELETE)) {
Path entryDeleted = (Path) event.context();
System.out.println("Existing entry deleted:" + entryDeleted);
} else if (kind.equals(StandardWatchEventKinds.ENTRY_MODIFY)) {
Path entryModified = (Path) event.context();
System.out.println("Existing entry modified:"+ entryModified);
}
}
}
- Output:
