XmlTextWriter.Flush操作和重设MemoryStream.Position = 0

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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。

<%@ 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>