<%@ WebHandler Language="C#" Class="Insus.NET.ShowOutSiteImage" %>

using System;
using System.Web;
using System.IO;

namespace Insus.NET
{
public class ShowOutSiteImage : IHttpHandler
{

public void ProcessRequest(HttpContext context)
{

string parameter = context.Request.QueryString["file"];

FileStream fs = new FileStream(parameter, FileMode.Open, FileAccess.Read);
BinaryReader br = new BinaryReader(fs);
Byte[] bytes = br.ReadBytes((Int32)fs.Length);
br.Close();
fs.Close();
context.Response.OutputStream.Write(bytes, 0, bytes.Length);
}

public bool IsReusable
{
get
{
return false;
}
}
}
}

<asp:Image ID="Image1" runat="server" ImageUrl="~/ShowOutSiteImage.ashx?file=图片路径" />