/**//// <summary>/// 防盗链Filter./// </summary>public class AntiOutSiteLinkAttribute : ActionFilterAttribute, IActionFilter{    public AntiOutSiteLinkAttribute(FileType fileType)    {        this.FileType = fileType;    }    /**//// <summary>    /// 请求的文件类型.(文件或图片)    /// </summary>    public FileType FileType { get; set; }    IActionFilter 成员#region IActionFilter 成员    void IActionFilter.OnActionExecuting(ActionExecutingContext filterContext)    {        HttpContextBase httpContext = filterContext.HttpContext;        if (null != httpContext.Request.UrlReferrer)        {            string serverDomain = httpContext.Request.Url.Host;            string refDomain = httpContext.Request.UrlReferrer.Host;            if (GetRootDomain(refDomain).Equals(GetRootDomain(serverDomain), StringComparison.OrdinalIgnoreCase))            {                return;//如果根域名相同就返回            }        }        ContentResult cr = new ContentResult();        if (FileType == FileType.Image)        {            cr.ContentType = "image/jpeg";            FileInfo fi = new FileInfo(httpContext.Server.MapPath("~/Content/images/outsitelink.jpg"));            if (fi.Exists)            {                httpContext.Response.WriteFile(fi.FullName);            }            else            {                Bitmap bmp = new Bitmap(200, 50);                Graphics g = Graphics.FromImage(bmp);                g.FillRectangle(Brushes.White, 0, 0, 200, 50);                g.DrawString("请不要盗链", new Font("Arial", 15), Brushes.Red, new PointF(0, 0));                bmp.Save(httpContext.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Gif);            }        }        else        {            cr.ContentType = "text/html";            cr.Content = string.Format("请不要盗链。返回<a href=http://www.mamicode.com/‘{0}‘>{1}", Utils.AbsoluteWebRoot, BlogSettings.Instance.Name);        }        //将当前的上下文的ActionResult设置为我们的cr(ContentResult)        filterContext.Result = cr;    }    #endregion    /**//// <summary>    /// 获取网站的根域名    /// </summary>    /// <param name="domain">网站的域名，不带"Http://"</param>    /// <returns></returns>    private string GetRootDomain(string domain)    {        if (string.IsNullOrEmpty(domain))        {            throw new ArgumentNullException("参数‘domain‘不能为空");        }        string[] arr = domain.Split(new[] { ‘.‘ }, StringSplitOptions.RemoveEmptyEntries);        if (arr.Length <= 2)        {            return domain;        }        else        {            return arr[arr.Length - 2] + "." + arr[arr.Length - 1];        }    }}public enum FileType{    File = 1,    Image}

public class FilesController : BaseController{    [AntiOutSiteLink(FileType.Image)]    public ActionResult Image(string file)    {        return Content("Image From 4mvc");    }     [AntiOutSiteLink(FileType.File)]    public ActionResult File(string file)    {        return Content("File From 4mvc");    }}