import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.WatchEvent;
import java.nio.file.WatchEvent.Kind;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.Map;
import java.util.WeakHashMap;
import static java.nio.file.StandardWatchEventKind.*;
public class FileMonTest {
    public static void main(String[] args) throws Exception {
        if (args.length != 1) {
            throw new Exception("Usage: FileMonTest <path>");
        }
        WatchService ws = FileSystems.getDefault().newWatchService();
        Path p = Paths.get(args[0]);
        register(ws, p);
        while (true) {
            WatchKey k = ws.take();
            for (WatchEvent e : k.pollEvents()) {
                Object ctx = e.context();
                if (ctx instanceof Path) {
                    ctx = keys.get(k).resolve((Path) ctx);
                }
                int count = e.count();
                if (count > 1) {
                    System.out.print("[" + count + "x] ");
                }
                Kind kind = e.kind();
                if (kind == ENTRY_CREATE) {
                    System.out.println("Created: " + ctx);
                    register(ws, (Path) ctx);
                } else if (kind == ENTRY_MODIFY) {
                    System.out.println("Modified: " + ctx);
                } else if (kind == ENTRY_DELETE) {
                    System.out.println("Deleted: " + ctx);
                } else {
                    System.out.println("Other event: " + kind + " on " + ctx);
                }
            }
            k.reset();
        }
    }
    private static final Map<WatchKey,Path> keys = new WeakHashMap<WatchKey,Path>();
    private static void register(final WatchService ws, Path p) throws IOException {
        Files.walkFileTree(p, new SimpleFileVisitor<Path>() {
            public @Override FileVisitResult preVisitDirectory(Path dir) {
                try {
                    keys.put(dir.register(ws, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY, OVERFLOW), dir);
                    System.out.println("Watching: " + dir);
                    return FileVisitResult.CONTINUE;
                } catch (IOException x) {
                    System.err.println("watch " + dir + ": " + x);
                    return FileVisitResult.SKIP_SUBTREE;
                }
            }
            public @Override FileVisitResult preVisitDirectoryFailed(Path dir, IOException x) {
                System.err.println(dir + ": " + x);
                return FileVisitResult.CONTINUE;
            }
            public @Override FileVisitResult visitFileFailed(Path file, IOException x) {
                System.err.println(file + ": " + x);
                return FileVisitResult.CONTINUE;
            }
        });
    }
}