import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Paths;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.List;

public class FileWatchServiceDemo {

  public static void main(String[] args) throws IOException, InterruptedException {
    WatchService watchService = FileSystems.getDefault().newWatchService();

    String filePath = "D:/aa";

    Paths.get(filePath).register(watchService, StandardWatchEventKinds.ENTRY_CREATE,
        StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_DELETE);

    while(true){
      WatchKey key = watchService.take();
      List<WatchEvent<?>> watchEvents = key.pollEvents();
      for (WatchEvent<?> event : watchEvents) {
        if(StandardWatchEventKinds.ENTRY_CREATE == event.kind()){
          System.out.println("创建：[" + filePath + "/" + event.context() + "]");
        }
        if(StandardWatchEventKinds.ENTRY_MODIFY == event.kind()){
          System.out.println("修改：[" + filePath + "/" + event.context() + "]");
        }
        if(StandardWatchEventKinds.ENTRY_DELETE == event.kind()){
          System.out.println("删除：[" + filePath + "/" + event.context() + "]");
        }
        
      }
      key.reset();
    }
  }
}

 StandardWatchEventKinds.ENTRY_CREATE //创建
 StandardWatchEventKinds.ENTRY_MODIFY //修改
 StandardWatchEventKinds.ENTRY_DELETE //删除