ASP.NET 图片放盗链（不能防下载）

/// <summary>    /// ImgHandler     /// http://blog.csdn.net/bluceyoung    /// </summary>    public class ImgHandler : IHttpHandler    {        public void ProcessRequest(HttpContext context)        {            string imgURL = context.Request.Url.AbsolutePath;            if (context.Request.UrlReferrer == null)//盗用图片            {                imgURL = context.Request.MapPath("bb.jpg");            }                       context.Response.ContentType = GetContentType(imgURL);            context.Response.WriteFile(imgURL);        }               private  string GetContentType(string url)        {            switch (Path.GetExtension(url))            {                case ".gif":                    return "Image/gif";                case ".jpg":                    return "Image/jpeg";                case ".png":                    return "Image/png";                default:                    break;            }            return null;        }               public bool IsReusable        {            get { return false; }        }    }