使用XlmWrite把一个xml文件写入输出流中。在（demo2.aspx运行时显示xml文档）

  protected void Page_Load(object sender, EventArgs e)
        {
            XmlWriterSettings settings = new XmlWriterSettings();
            settings.Encoding = System.Text.Encoding.UTF8;
            settings.Indent = true;

            //using(XmlWriter write = XmlWriter.Create(Server.MapPath("newbook.xml")))
            using (XmlWriter write = XmlWriter.Create(this.Response.Output, settings))
            {
                write.WriteStartDocument();//开始写
                write.WriteStartElement("books");//写根节点
                write.WriteStartElement("book");//book节点开始
                write.WriteStartAttribute("id");//给book增加属性，属性名为id
                write.WriteValue("1");//设置属性id的值为1
                write.WriteEndAttribute();//结束属性id的设置
                write.WriteStartElement("author");//author节点开始
                write.WriteString("john");//author节点的内容
                write.WriteEndElement();//结束author节点
                write.WriteEndElement();//结束book节点
                write.WriteStartElement("book");
                write.WriteStartElement("publisher");
                write.WriteString("ASP.NET详解");
                write.WriteEndElement();//结束books节点
                write.WriteEndElement();
                write.WriteEndElement();
            }
        }