private void DataBackupButton_Click(object sender, EventArgs e)
{
    FolderBrowserDialog fbd = new FolderBrowserDialog();
    fbd.Description = "选择文件备份路径";
    if (fbd.ShowDialog() == DialogResult.OK)
    {
        string[] files = { "b.mdf", "c.ldf", "resource\\A" };
        string selectedPath = fbd.SelectedPath;
        foreach (string f in files)
        {
            string sourcePath = Path.GetFullPath(f);
            string destinationPath = Path.Combine(selectedPath, f);
            if (File.Exists(sourcePath))
            {
                Copy(new FileInfo(sourcePath),destinationPath);
            }
            else if (Directory.Exists(sourcePath))
            {
                Copy(new DirectoryInfo(sourcePath), destinationPath);
            }
        }
    }
}

private void Copy(FileSystemInfo fsi, string destPath)
{
    if (fsi is FileInfo)
    {
        ((FileInfo)fsi).CopyTo(destPath);
    }
    else if (fsi is DirectoryInfo)
    {
        Directory.CreateDirectory(destPath);
        foreach (FileSystemInfo child in ((DirectoryInfo)fsi).GetFileSystemInfos())
        {
            Copy(child, Path.Combine(destPath, child.Name));
        }
    }
}