Java使用WatchService监控文件内容变化的示例

// 监控文件的变化，重新加载executor.submit(new Runnable() {  @Override  public void run() {    try {      final Path path = FileSystems.getDefault().getPath(getMonitorDir());      System.out.println(path);      final WatchService watchService = FileSystems.getDefault().newWatchService();      final WatchKey watchKey = path.register(watchService, StandardWatchEventKinds.ENTRY_MODIFY);      while (true) {        final WatchKey wk = watchService.take();        for (WatchEvent<?> event : wk.pollEvents()) {          final Path changed = (Path) event.context();          Path absolute = path.resolve(changed);          File configFile = absolute.toFile();          long lastModified = configFile.lastModified();          logger.info(lastModified + "----------------");          // 利用文件时间戳，防止触发两次          if (changed.endsWith(getLicenseName()) && lastModified != LAST_MOD && configFile.length > 0) {            logger.info("----------------- reloading -----------------");            LAST_MOD = lastModified; // 保存上一次时间戳            UPDATED = true; // 设置标志位          }        }        if (UPDATED) {          reloadFile(); // 重新加载        }        // reset the key        boolean valid = wk.reset();        if (!valid) {          logger.error("watch key invalid!");        }      }    } catch (Exception e) {      logger.error("");    }  }});