原文发布时间为：2008-08-10 —— 来源于本人的百度文章 [由搬家工具导入]

fileToXml类：

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using System.IO;
using System.Xml;

/// <summary>
/// fileToXml 的摘要说明
/// </summary>
public class fileToXml
{
public fileToXml()
{
   //
   // TODO: 在此处添加构造函数逻辑
   //
}
    public static void toXml(FileUpload fu, string xmlpath, Guid id)
    {
        if (fu.HasFile)
        {
            string fpath = fu.FileName;
            int fileLength = fu.PostedFile.ContentLength;
           Byte[] fileBytes = new Byte[fileLength];
            Stream strm = fu.PostedFile.InputStream;
            strm.Read(fileBytes, 0, fileLength);
            XmlDocument dom = new XmlDocument();
            if (!File.Exists(xmlpath))
            {
                XmlDeclaration xdec = dom.CreateXmlDeclaration("1.0", "utf-8", null);
                dom.AppendChild(xdec);

                XmlElement root = dom.CreateElement("File");
                dom.AppendChild(root);

                XmlElement father = dom.CreateElement("Image");
                root.AppendChild(father);

                XmlElement guid = dom.CreateElement("Guid");
                guid.InnerText = id.ToString();
                father.AppendChild(guid);

                XmlElement imgData = http://www.mamicode.com/dom.CreateElement("imgData");
                imgData.InnerText = Convert.ToBase64String(fileBytes);
                father.AppendChild(imgData);

                dom.Save(xmlpath);
            }
            else
            {

                dom.Load(xmlpath);
                XmlNode root = dom.SelectSingleNode("File");
                XmlElement father = dom.CreateElement("Image");
                root.AppendChild(father);

                XmlElement guid = dom.CreateElement("Guid");
                guid.InnerText = id.ToString();
                father.AppendChild(guid);

                XmlElement imgData = http://www.mamicode.com/dom.CreateElement("imgData");
                imgData.InnerText = Convert.ToBase64String(fu.FileBytes);//这是利用fileupload控件本身的方法获取二进制流
                father.AppendChild(imgData);

                dom.Save(xmlpath);
            }
        }
    }
}
------------------------------

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using System.Xml;
using System.IO;

public partial class Default3 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string xmlpath = Server.MapPath("~/App_Data/imgToBry.xml");
        Guid gid = Guid.NewGuid();
        fileToXml.toXml(FileUpload1, xmlpath, gid);

        Session["gid"] = gid;
    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        XmlDocument dom = new XmlDocument();
        dom.Load(Server.MapPath("~/App_Data/imgToBry.xml"));
        XmlNodeList xnl = dom.SelectSingleNode("//Image[Guid='" + Session["gid"].ToString() + "']").ChildNodes;
        for (int i = 0; i < xnl.Count; i++) ;
        {
            string imgdata = http://www.mamicode.com/xnl.Item(1).InnerText;
            Response.OutputStream.Write(Convert.FromBase64String(imgdata),0,imgdata.Length);
            Response.End();
        }
    }
    protected void Button3_Click(object sender, EventArgs e)
    {
        XmlDocument dom = new XmlDocument();
        dom.Load(Server.MapPath("~/App_Data/imgToBry.xml"));
        XmlNodeList xnl = dom.SelectSingleNode("//Image[Guid='" + Session["gid"].ToString() + "']").ChildNodes;
        for (int i = 0; i < xnl.Count; i++) ;
        {
            string imgdata = http://www.mamicode.com/xnl.Item(1).InnerText;
            FileStream fs = new FileStream(Server.MapPath("~/xml.gif"), FileMode.Create, FileAccess.Write);
            BinaryWriter bw = new BinaryWriter(fs);
            bw.Write(Convert.FromBase64String(imgdata));
            bw.Close();
            fs.Close();           
        }
        Image1.ImageUrl="~/xml.gif";
    }
}

net9：图片变成二进制流存入XML文档，从XML文档中读出图片以及从XML文档中读取并创建图片文件