C# xml格式化输出函数

   private string FormatXml(string sUnformattedXml)
        {
            XmlDocument xd = new XmlDocument();
            xd.LoadXml(sUnformattedXml);
            StringBuilder sb = new StringBuilder();
            StringWriter sw = new StringWriter(sb);
            XmlTextWriter xtw = null;
            try
            {
                xtw = new XmlTextWriter(sw);
                xtw.Formatting = Formatting.Indented;
                xtw.Indentation = 1;
                xtw.IndentChar = '\t';
                xd.WriteTo(xtw);
            }
            finally
            {
                if (xtw != null)
                    xtw.Close();
            }
            return sb.ToString();
        }