XmlReader 读取器读取内存流 MemoryStream 的注意事项

网络编程 2024/11/18 佚名

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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。

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>
VB.NET

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)
Response.Clear
Response.ContentType = "text/xml"
Dim msXml As MemoryStream = New MemoryStream
Dim xmlWriter As XmlTextWriter = 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
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
msXml.Position = 0
Dim xmlReader As XmlReader = XmlReader.Create(msXml)
While xmlReader.Read
If xmlReader.Name = "rss" Then
Response.Write(xmlReader.ReadOuterXml)
End If
End While
Response.End
msXml.Close
xmlWriter.Close
xmlReader.Close
End Sub

XmlReader,读取器读取内存流,MemoryStream,的注意事项

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