XmlReader 读取器读取内存流 MemoryStream 的注意事项

MemoryStream对象提供了无需进行IO就可以创建Stream的方法，XmlTextWriter和XmlReader提供快速书写和读取XML内容的方法，结合MemoryStream，就可以直接在内存中构造XmlTextWriter，并用XmlReader进行读取。

使用MemoryStream和XmlTextWriter进行书写XML,需要注意两点：XmlTextWriter.Flush操作和重设MemoryStream.Position = 0。

C# 

<% @ Page Language = " C# " %>
<% @ Import Namespace = " System.Xml "   %>
<% @ Import Namespace = " System.IO "   %>
<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >

< script  runat ="server" >
  protected  void  Button1_Click(object sender, EventArgs e)
  {
    Response.Clear();
    Response.ContentType  =   " text/xml " ;
    MemoryStream msXml  =   new  MemoryStream();
    XmlTextWriter xmlWriter  =   new  XmlTextWriter(msXml, Encoding.UTF8);
    xmlWriter.WriteStartElement( " rss " );
    xmlWriter.WriteAttributeString( " version " ,  " 2.0 " );
    xmlWriter.WriteStartElement( " channel " );
    xmlWriter.WriteElementString( " title " ,  " 【孟宪会之精彩世界】 " );
    xmlWriter.WriteElementString( " link " ,  " http://dotnet.aspx.cc/Rss.aspx " );
    xmlWriter.WriteElementString( " description " ,  " NET开发技术。 " );
    xmlWriter.WriteElementString( " language " ,  " zh-CN " );
    xmlWriter.WriteElementString( " copyright " ,  " Copyright 1999-2007【孟宪会之精彩世界】 " );
    xmlWriter.WriteElementString( " managingEditor " ,  " amxh[AT]21cn.com " );
    xmlWriter.WriteStartElement( " image " );
    xmlWriter.WriteElementString( " title " ,  " 【孟宪会之精彩世界】 " );
    xmlWriter.WriteElementString( " width " ,  " 144 " );
    xmlWriter.WriteElementString( " height " ,  " 35 " );
    xmlWriter.WriteElementString( " link " ,  " http://dotnet.aspx.cc/ " );
    xmlWriter.WriteElementString( " url " ,  " http://dotnet.aspx.cc/Images/LogoRss.gif " );
    xmlWriter.WriteEndElement();

     // 循环读出数据库内容列表，忽略
     // while (objReader.Read())
     // {
     //   xmlWriter.WriteStartElement("item");
     //   xmlWriter.WriteElementString("title", objReader.GetString(0));
     //   xmlWriter.WriteElementString("description", objReader.GetString(1));
     //   xmlWriter.WriteElementString("link", "http://dotnet.aspx.cc/article/a933b187-06c3-4263-9eec-414a54d9c815/read.aspx");
     //   xmlWriter.WriteElementString("pubDate", objReader.GetDateTime(3).ToString("G"));
     //   xmlWriter.WriteEndElement();
     // }
     // objReader.Close();
    xmlWriter.WriteStartElement( " item " );
    xmlWriter.WriteElementString( " title " ,  " ASP.NET 2.0中直接将Access数据库导入到Excel文件中 " );
    xmlWriter.WriteElementString( " description " ,  " ASP.NET 2.0中直接将Access数据库导入到Excel文件中 " );
    xmlWriter.WriteElementString( " link " ,  " http://dotnet.aspx.cc/article/a933b187-06c3-4263-9eec-414a54d9c815/read.aspx " );
    xmlWriter.WriteElementString( " pubDate " ,  " Sat, 02 Dec 2006 09:39:58 GMT " );
    xmlWriter.WriteEndElement();
    xmlWriter.WriteEndElement();
    xmlWriter.WriteEndElement();
    xmlWriter.Flush();   //  确保书写器更新到Stream中；
    msXml.Position  =   0 ;  //  重置流的位置，以便我们可以从头读取     
    XmlReader xmlReader  =  XmlReader.Create(msXml);
     while  (xmlReader.Read())
    {
       if  (xmlReader.Name  ==   " rss " )
      {
        Response.Write(xmlReader.ReadOuterXml());
      }
    }
    Response.End();
    msXml.Close();
    xmlWriter.Close();
    xmlReader.Close();
  }
</ script >

< html  xmlns ="http://www.w3.org/1999/xhtml" >
< head  runat ="server" >
   < title > XmlReader 读取器读取内存流 MemoryStream 的注意事项 </ title >
</ head >
< body >
   < form  id ="form1"  runat ="server" >
     < asp:Button  ID ="Button1"  runat ="server"  OnClick ="Button1_Click"  Text ="读取数据"   />
   </ form >
</ body >
</ html >