XML与DataTable/DataSet互转(C#) 把数据库中表的内容转存为XML文件

/**//// <summary>
    /// 把DataSet、DataTable、DataView格式转换成XML字符串、XML文件
    /// </summary>
    public class DataToXml
    {
        /**//// <summary>
        /// 将DataTable对象转换成XML字符串
        /// </summary>
        /// <param name="dt">DataTable对象</param>
        /// <returns>XML字符串</returns>
        public static string CDataToXml(DataTable dt)
        {
            if (dt != null)
            {
                MemoryStream ms = null;
                XmlTextWriter XmlWt = null;
                try
                {
                    ms = new MemoryStream();
                    //根据ms实例化XmlWt
                    XmlWt = new XmlTextWriter(ms, Encoding.Unicode);
                    //获取ds中的数据
                    dt.WriteXml(XmlWt);
                    int count = (int)ms.Length;
                    byte[] temp = new byte[count];
                    ms.Seek(0, SeekOrigin.Begin);
                    ms.Read(temp, 0, count);
                    //返回Unicode编码的文本
                    UnicodeEncoding ucode = new UnicodeEncoding();
                    string returnValue = ucode.GetString(temp).Trim();
                    return returnValue;
                }
                catch (System.Exception ex)
                {
                    throw ex;
                }
                finally
                {
                    //释放资源
                    if (XmlWt != null)
                    {
                        XmlWt.Close();
                        ms.Close();
                        ms.Dispose();
                    }
                }
            }
            else
            {
                return "";
            }
        }
        /**//// <summary>
        /// 将DataSet对象中指定的Table转换成XML字符串
        /// </summary>
        /// <param name="ds">DataSet对象</param>
        /// <param name="tableIndex">DataSet对象中的Table索引</param>
        /// <returns>XML字符串</returns>
        public static string CDataToXml(DataSet ds, int tableIndex)
        {
            if (tableIndex != -1)
            {
                return CDataToXml(ds.Tables[tableIndex]);
            }
            else
            {
                return CDataToXml(ds.Tables[0]);
            }
        }
        /**//// <summary>
        /// 将DataSet对象转换成XML字符串
        /// </summary>
        /// <param name="ds">DataSet对象</param>
        /// <returns>XML字符串</returns>
        public static string CDataToXml(DataSet ds)
        {
            return CDataToXml(ds, -1);
        }
        /**//// <summary>
        /// 将DataView对象转换成XML字符串
        /// </summary>
        /// <param name="dv">DataView对象</param>
        /// <returns>XML字符串</returns>
        public static string CDataToXml(DataView dv)
        {
            return CDataToXml(dv.Table);
        }

        /**//// <summary>
        /// 将DataSet对象数据保存为XML文件
        /// </summary>
        /// <param name="dt">DataSet</param>
        /// <param name="xmlFilePath">XML文件路径</param>
        /// <returns>bool值</returns>
        public static bool CDataToXmlFile(DataTable dt, string xmlFilePath)
        {
            if ((dt != null) && (!string.IsNullOrEmpty(xmlFilePath)))
            {
                string path = HttpContext.Current.Server.MapPath(xmlFilePath);
                MemoryStream ms = null;
                XmlTextWriter XmlWt = null;
                try
                {
                    ms = new MemoryStream();
                    //根据ms实例化XmlWt
                    XmlWt = new XmlTextWriter(ms, Encoding.Unicode);
                    //获取ds中的数据
                    dt.WriteXml(XmlWt);
                    int count = (int)ms.Length;
                    byte[] temp = new byte[count];
                    ms.Seek(0, SeekOrigin.Begin);
                    ms.Read(temp, 0, count);
                    //返回Unicode编码的文本
                    UnicodeEncoding ucode = new UnicodeEncoding();
                    //写文件
                    StreamWriter sw = new StreamWriter(path);
                    sw.WriteLine("<?xml version="1.0" encoding="utf-8"?>");
                    sw.WriteLine(ucode.GetString(temp).Trim());
                    sw.Close();
                    return true;
                }
                catch (System.Exception ex)
                {
                    throw ex;
                }
                finally
                {
                    //释放资源
                    if (XmlWt != null)
                    {
                        XmlWt.Close();
                        ms.Close();
                        ms.Dispose();
                    }
                }
            }
            else
            {
                return false;
            }
        }
        /**//// <summary>
        /// 将DataSet对象中指定的Table转换成XML文件
        /// </summary>
        /// <param name="ds">DataSet对象</param>
        /// <param name="tableIndex">DataSet对象中的Table索引</param>
        /// <param name="xmlFilePath">xml文件路径</param>
        /// <returns>bool]值</returns>
        public static bool CDataToXmlFile(DataSet ds, int tableIndex, string xmlFilePath)
        {
            if (tableIndex != -1)
            {
                return CDataToXmlFile(ds.Tables[tableIndex], xmlFilePath);
            }
            else
            {
                return CDataToXmlFile(ds.Tables[0], xmlFilePath);
            }
        }
        /**//// <summary>
        /// 将DataSet对象转换成XML文件
        /// </summary>
        /// <param name="ds">DataSet对象</param>
        /// <param name="xmlFilePath">xml文件路径</param>
        /// <returns>bool]值</returns>
        public static bool CDataToXmlFile(DataSet ds, string xmlFilePath)
        {
            return CDataToXmlFile(ds, -1, xmlFilePath);
        }
        /**//// <summary>
        /// 将DataView对象转换成XML文件
        /// </summary>
        /// <param name="dv">DataView对象</param>
        /// <param name="xmlFilePath">xml文件路径</param>
        /// <returns>bool]值</returns>
        public static bool CDataToXmlFile(DataView dv, string xmlFilePath)
        {
            return CDataToXmlFile(dv.Table, xmlFilePath);
        }
    }

/**//// <summary>
    /// XML形式的字符串、XML文江转换成DataSet、DataTable格式
    /// </summary>
    public class XmlToData
    {
        /**//// <summary>
        /// 将Xml内容字符串转换成DataSet对象
        /// </summary>
        /// <param name="xmlStr">Xml内容字符串</param>
        /// <returns>DataSet对象</returns>
        public static DataSet CXmlToDataSet(string xmlStr)
        {
            if (!string.IsNullOrEmpty(xmlStr))
            {
                StringReader StrStream = null;
                XmlTextReader Xmlrdr = null;
                try
                {
                    DataSet ds = new DataSet();
                    //读取字符串中的信息
                    StrStream = new StringReader(xmlStr);
                    //获取StrStream中的数据
                    Xmlrdr = new XmlTextReader(StrStream);
                    //ds获取Xmlrdr中的数据               
                    ds.ReadXml(Xmlrdr);
                    return ds;
                }
                catch (Exception e)
                {
                    throw e;
                }
                finally
                {
                    //释放资源
                    if (Xmlrdr != null)
                    {
                        Xmlrdr.Close();
                        StrStream.Close();
                        StrStream.Dispose();
                    }
                }
            }
            else
            {
                return null;
            }
        }
        /**//// <summary>
        /// 将Xml字符串转换成DataTable对象
        /// </summary>
        /// <param name="xmlStr">Xml字符串</param>
        /// <param name="tableIndex">Table表索引</param>
        /// <returns>DataTable对象</returns>
        public static DataTable CXmlToDatatTable(string xmlStr, int tableIndex)
        {
            return CXmlToDataSet(xmlStr).Tables[tableIndex];
        }
        /**//// <summary>
        /// 将Xml字符串转换成DataTable对象
        /// </summary>
        /// <param name="xmlStr">Xml字符串</param>
        /// <returns>DataTable对象</returns>
        public static DataTable CXmlToDatatTable(string xmlStr)
        {
            return CXmlToDataSet(xmlStr).Tables[0];
        }
        /**//// <summary>
        /// 读取Xml文件信息,并转换成DataSet对象
        /// </summary>
        /// <remarks>
        /// DataSet ds = new DataSet();
        /// ds = CXmlFileToDataSet("/XML/upload.xml");
        /// </remarks>
        /// <param name="xmlFilePath">Xml文件地址</param>
        /// <returns>DataSet对象</returns>
        public static DataSet CXmlFileToDataSet(string xmlFilePath)
        {
            if (!string.IsNullOrEmpty(xmlFilePath))
            {
                string path = HttpContext.Current.Server.MapPath(xmlFilePath);
                StringReader StrStream = null;
                XmlTextReader Xmlrdr = null;
                try
                {
                    XmlDocument xmldoc = new XmlDocument();
                    //根据地址加载Xml文件
                    xmldoc.Load(path);

                    DataSet ds = new DataSet();
                    //读取文件中的字符流
                    StrStream = new StringReader(xmldoc.InnerXml);
                    //获取StrStream中的数据
                    Xmlrdr = new XmlTextReader(StrStream);
                    //ds获取Xmlrdr中的数据
                    ds.ReadXml(Xmlrdr);
                    return ds;
                }
                catch (Exception e)
                {
                    throw e;
                }
                finally
                {
                    //释放资源
                    if (Xmlrdr != null)
                    {
                        Xmlrdr.Close();
                        StrStream.Close();
                        StrStream.Dispose();
                    }
                }
            }
            else
            {
                return null;
            }
        }
        /**//// <summary>
        /// 读取Xml文件信息,并转换成DataTable对象
        /// </summary>
        /// <param name="xmlFilePath">xml文江路径</param>
        /// <param name="tableIndex">Table索引</param>
        /// <returns>DataTable对象</returns>
        public static DataTable CXmlToDataTable(string xmlFilePath, int tableIndex)
        {
            return CXmlFileToDataSet(xmlFilePath).Tables[tableIndex];
        }
        /**//// <summary>
        /// 读取Xml文件信息,并转换成DataTable对象
        /// </summary>
        /// <param name="xmlFilePath">xml文江路径</param>
        /// <returns>DataTable对象</returns>
        public static DataTable CXmlToDataTable(string xmlFilePath)
        {
            return CXmlFileToDataSet(xmlFilePath).Tables[0];
        }
    }

using System;
using System.Data;
using System.IO;
using System.Xml;
using System.Text;
// 相应C#代码：
private string ConvertDataTableToXML(DataTable xmlDS)
{
     MemoryStream stream = null;
     XmlTextWriter writer = null;
     try
     {
         stream = new MemoryStream();
         writer = new XmlTextWriter(stream, Encoding.Default);
         xmlDS.WriteXml(writer);
         int count = (int)stream.Length;
         byte[] arr = new byte[count];
         stream.Seek(0, SeekOrigin.Begin);
         stream.Read(arr, 0, count);
         UTF8Encoding utf = new UTF8Encoding();
         return utf.GetString(arr).Trim();
     }
     catch
     {
         return String.Empty;
     }
     finally
     {
         if (writer != null) writer.Close();
     }
}

private DataSet ConvertXMLToDataSet(string xmlData)
{
   StringReader stream = null;
   XmlTextReader reader = null;
   try
   {
     DataSet xmlDS = new DataSet();
     stream = new StringReader(xmlData);
     reader = new XmlTextReader(stream);
     xmlDS.ReadXml(reader);
     return xmlDS;
   }
   catch (Exception ex)
   {
     string strTest = ex.Message;
     return null;
   }
   finally
   {
     if (reader != null)
     reader.Close();
   }
}

把数据库中表的内容转存为XML文件
SqlConnection conn = new SqlConnection("server=.;database=db;uid=sa;pwd=");
SqlCommand cmd = conn.CreateCommand();
//把列的内容作为属性，根元素名子为<root>
cmd.CommandText = "select * from student for xml auto,root('root')";
conn.Open();
XmlReader xr = cmd.ExecuteXmlReader();
XmlDocument dd = new XmlDocument();
dd.Load(xr); ;
XmlNode xx = dd.FirstChild;   //取得根元素
XmlDeclaration xd = dd.CreateXmlDeclaration("1.0", "utf-8", "yes");   //创建XML声明
dd.InsertBefore(xd,xx);   //在根元素前加入XML声明
dd.Save(Server.MapPath("tt.config"));
conn.Close();
执行结果：
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<root>
<student sno="101" sname="李军" ssex="男" sbirthday="1976-02-20T00:00:00" class="95033" />
<student sno="103" sname="陆君" ssex="男" sbirthday="1974-06-03T00:00:00" class="95031" />
</root>

如果把上面的SqlCommand对象的CommandText改为如下：
cmd.CommandText = "select * from student for xml auto,root('root'),elements";
执行结果如下：
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<root>
<student>
    <sno>101</sno>
    <sname>李军</sname>
    <ssex>男</ssex>
    <sbirthday>1976-02-20T00:00:00</sbirthday>
    <class>95033</class>
</student>
<student>
    <sno>103</sno>
    <sname>陆君</sname>
    <ssex>男</ssex>
    <sbirthday>1974-06-03T00:00:00</sbirthday>
    <class>95031</class>
</student>
</root>