Java tutorial
import java.io.IOException; import java.nio.file.FileSystems; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; 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; import java.text.SimpleDateFormat; import java.util.Date; import java.util.concurrent.TimeUnit; class SecurityWatch { WatchService watchService; private void register(Path path, Kind<Path> kind) throws IOException { path.register(watchService, kind); } public void watchVideoCamera(Path path) throws IOException, InterruptedException { watchService = FileSystems.getDefault().newWatchService(); register(path, StandardWatchEventKinds.ENTRY_CREATE); OUTERMOST: while (true) { final WatchKey key = watchService.poll(11, TimeUnit.SECONDS); if (key == null) { System.out.println("The video camera is jammed - security watch system is canceled!"); break; } else { for (WatchEvent<?> watchEvent : key.pollEvents()) { final Kind<?> kind = watchEvent.kind(); if (kind == StandardWatchEventKinds.OVERFLOW) { continue; } if (kind == StandardWatchEventKinds.ENTRY_CREATE) { //get the filename for the event final WatchEvent<Path> watchEventPath = (WatchEvent<Path>) watchEvent; final Path filename = watchEventPath.context(); final Path child = path.resolve(filename); if (Files.probeContentType(child).equals("image/jpeg")) { //print it out the video capture time SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss"); System.out.println("Video capture successfully at: " + dateFormat.format(new Date())); } else { System.out.println("The video camera capture format failed! This could be a virus!"); break OUTERMOST; } } } boolean valid = key.reset(); if (!valid) { break; } } } watchService.close(); } } public class Main { public static void main(String[] args) { final Path path = Paths.get("C:/security"); SecurityWatch watch = new SecurityWatch(); try { watch.watchVideoCamera(path); } catch (IOException | InterruptedException ex) { System.err.println(ex); } } }