// 获取文件夹绝对路径    显示在 txtbox 控件里

System.Windows.Forms.FolderBrowserDialog folder = new System.Windows.Forms.FolderBrowserDialog();

if (folder.ShowDialog() == DialogResult.OK)
{
  this.txtboxPath.Text = folder.SelectedPath;              

  }

// 获取文件和路径名 一起显示在 txtbox 控件里

OpenFileDialog dialog = new OpenFileDialog();
if (dialog .ShowDialog() == DialogResult.OK)
{
  this.txtboxPath.SelectedText = dialog.FileName;                   

}

 //如果只显示文件名

OpenFileDialog dialog = new OpenFileDialog();
if (dialog .ShowDialog() == DialogResult.OK)
{
  this.txtboxPath.SelectedText = dialog.SafeFileName;                   

}