关于java一些零零散散的点(三)

Path path = Paths.get("path"); 
        if (Files.exists(path)) {
            try (WatchService watchService = FileSystems.getDefault().newWatchService()) {
                path.register( 
                        watchService,
                        StandardWatchEventKinds.ENTRY_CREATE,
                        StandardWatchEventKinds.ENTRY_MODIFY,
                        StandardWatchEventKinds.ENTRY_DELETE
                );
                while (true) {
                    WatchKey key = watchService.take();  // 阻塞
                    for (WatchEvent<?> event : key.pollEvents()) {
                        WatchEvent<Path> ev = (WatchEvent<Path>) event;
                        Path file = ev.context(); // 得到事件中的文档

                        if (StandardWatchEventKinds.ENTRY_CREATE.equals(event.kind())) {
                            // 创建时
                        }

                        if (StandardWatchEventKinds.ENTRY_MODIFY.equals(event.kind())) {
                            // 修改时
                        }

                        if (StandardWatchEventKinds.ENTRY_DELETE.equals(event.kind())) {
                            // 删除时
                        }
                    }
                    key.reset(); // 处理成功后清除队列中的key，否则后续事件无法触发
                }
            } catch (IOException | InterruptedException e) {
                e.printStackTrace();
            }