C# xsd验证XML格式是否正确

            /// <summary>  
            /// 通过xsd验证xml格式是否正确，正确返回空字符串，错误返回提示  
            /// </summary>  
            /// <param name="xmlFile">xml文件</param>  
            /// <param name="xsdFile">xsd文件</param>  
            /// <param name="namespaceUrl">命名空间，无则默认为null</param>  
            /// <returns></returns>  
            public string XmlValidationByXsd(string xmlFile, string xsdFile, string namespaceUrl = null)
            {
                StringBuilder sb = new StringBuilder();
                XmlReaderSettings settings = new XmlReaderSettings();
                settings.ValidationType = ValidationType.Schema;
                settings.Schemas.Add(namespaceUrl, xsdFile);
                settings.ValidationEventHandler += (x, y) =>
                {
                    sb.AppendFormat("{0}", y.Message);
                };
                using (XmlReader reader = XmlReader.Create(xmlFile, settings))
                {
                    try
                    {
                        while (reader.Read()) ;
                    }
                    catch (XmlException ex)
                    {
                        sb.AppendFormat("{0}", ex.Message);
                    }
                }
                return sb.ToString();
            }