打开文件：

var dialog = new OpenFileDialog { Multiselect = false };            var result = dialog.ShowDialog();            if (result == true)            {                    using (var stream = dialog.File.OpenRead())                    {                        var buffer = new byte[stream.Length];                        stream.Read(buffer, 0, buffer.Length);                        var xaml = System.Text.Encoding.UTF8.GetString(buffer, 0, buffer.Length);                        .............................                        ................................                    }             }

保存文件：

var dialog = new SaveFileDialog(); 　　　　　　  dialog.Filter="文本文件(*.txt)|*.txt";            var result = dialog.ShowDialog();            //dialog.Filter = "文本文件|*.txt";            if (result == true)            {                using (var stream = dialog.OpenFile())                {                    Byte[] fileContent = Encoding.UTF8.GetBytes(saveXaml+strAll.ToString());                    stream.Write(fileContent, 0, fileContent.Length);                    stream.Close();                }            }