.net 文件夹是否存在的判断

protected void Button1_Click(object sender, EventArgs e)
    {
        string path = "";
        string physicsPath = Server.MapPath(Request.ApplicationPath); //将当前虚拟根路径转为实际物理路径
        string toFindDirectoryName = "ss"; //要查找的文件夹名
        FindDirectory(physicsPath + "\\", toFindDirectoryName, out path);//用递归的方式去查找文件夹
        if (!string.IsNullOrEmpty(path)) //如果存在，返回该文件夹所在的物理路径
        {
            //将该物理路径转为虚拟路径
            Response.Write(GetVirtualPath(path, Request.ApplicationPath));
        }
        else
        {
            //没有找到路径,创建新文件夹
            Directory.CreateDirectory(physicsPath + "\\" + toFindDirectoryName);
        }
    }

    /// <summary>
    /// 将物理路径转为虚拟路径
    /// </summary>
    /// <param name="physicsPath">物理路径</param>
    /// <param name="virtualRootPath">虚拟根路径</param>
    /// <returns></returns>
    private string GetVirtualPath(string physicsPath, string virtualRootPath)
    {
        int index = physicsPath.IndexOf(virtualRootPath.Substring(1));
        return "/" + physicsPath.Substring(index).Replace("\\", "/");
    }

    /// <summary>
    /// 在指定目录下递归查找子文件夹
    /// </summary>
    /// <param name="bootPath">根文件夹路径</param>
    /// <param name="directoryName">要查找的文件夹名</param>
    private void FindDirectory(string bootPath, string directoryName, out string filePath)
    {
        //在指定目录下递归查找子文件夹
        DirectoryInfo dir = new DirectoryInfo(bootPath);
        filePath = "";
        try
        {
            foreach (DirectoryInfo d in dir.GetDirectories()) //查找子文件夹
            {
                if (d.Name == directoryName) //找到,返回文件夹路径
                {
                    filePath = d.FullName;
                    break;
                }
                FindDirectory(bootPath + d.Name + "\\", directoryName, out filePath); //否则继续查找
            }
        }
        catch (Exception e)
        {
            Response.Write(e.Message);
        }

    }