using System;
using System.Web;

namespace CustomHandler{
public class JpgHandler : IHttpHandler{
public void ProcessRequest(HttpContext context){
// 獲取文件服務器端物理路徑
string FileName = context.Server.MapPath(context.Request.FilePath);
// 如果UrlReferrer為空，則顯示一張默認的禁止盜鏈的圖片
if (context.Request.UrlReferrer.Host == null){
context.Response.ContentType = "image/JPEG";
context.Response.WriteFile("/error.jpg");
}else{
// 如果 UrlReferrer中不包含自己站點主機域名，則顯示一張默認的禁止盜鏈的圖片
if (context.Request.UrlReferrer.Host.IndexOf("yourdomain.com") > 0){
context.Response.ContentType = "image/JPEG";
context.Response.WriteFile(FileName);
}else{
context.Response.ContentType = "image/JPEG";
context.Response.WriteFile("/error.jpg");
}
}
}

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

csc /t:library /r:System.Web.dll CustomHandler.cs

<system.web>
<httpHandlers>
<add path="*.jpg" verb="*" type="CustomHandler.JpgHandler, CustomHandler" />
</httpHandlers>
</system.web>