文件夹是 2023060200.tar 这种名称，现在要把文件夹名称截取，只是留下 2023060200 这种格式的，批量处理

  public static void main(String[] args) {
        String folderPath = "D:\\data\\"; // 指定文件夹路径

        File folder = new File(folderPath);
        File[] files = folder.listFiles();

        if (files != null) {
            for (File file : files) {
                if (file.isDirectory()) {
                    String oldFolderName = file.getName();
                    String newFolderName = getNewFolderName(oldFolderName);
                    renameFolder(file, newFolderName);
                }
            }
        }
    }

    private static String getNewFolderName(String oldFolderName) {
        int dotIndex = oldFolderName.lastIndexOf(".");
        if (dotIndex != -1) {
            return oldFolderName.substring(0, dotIndex);
        } else {
            return oldFolderName;
        }
    }

    private static void renameFolder(File folder, String newFolderName) {
        File newFolder = new File(folder.getParent(), newFolderName);
        if (folder.renameTo(newFolder)) {
            System.out.println("Renamed folder: " + folder.getName() + " to " + newFolderName);
        } else {
            System.out.println("Failed to rename folder: " + folder.getName());
        }
    }