如何用HttpModule拦截用户下载的文件

Question

出于网站信息安全考虑，我想通过HttpModule处理当用户请求下载word文件里，先将WORD转为PDF并打上水印，然后将转换后的PDF返回给用户

Answer 1

public class SafeDocHttpHandler:IHttpHandler
    {
        private HttpRequest Request
        {
            get { return HttpContext.Current.Request; }
        }
        private HttpResponse Response
        {
            get { return HttpContext.Current.Response; }
        }
        #region IHttpHandler 成员
        public bool IsReusable
        {
            get { return false; }
        }        public void ProcessRequest(HttpContext context)
        {
            SPSite site = SPControl.GetContextSite(context);
            
            string userName = context.User.Identity.Name;
            if (site.RootWeb.CurrentUser != null || (userName != null && userName != string.Empty))
            {
                SPUser curuser = site.RootWeb.CurrentUser;                if (userName == string.Empty)
                    userName = curuser.LoginName;                if (userName == null || userName == string.Empty || !context.User.Identity.IsAuthenticated)
                {
                    context.Server.Transfer("/_layouts/login.aspx");
                    return;
                }
                else
                {
                    string downUserName = SPContext.Current.Web.CurrentUser.Name;
                    string filename = Path.GetFileName(context.Request.PhysicalPath);
                    string exten = Path.GetExtension(filename);                    //if (exten.Contains(".doc")&&!context.Request.Url.ToString().Contains("/chengguo"))
                    if (exten.Contains(".doc") || exten.Contains(".xls") || exten.Contains(".ppt"))
                    {
                        ws_doc27.WebService_Doc wsdoc = new ws_doc27.WebService_Doc();
                        wsdoc.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;
                        AttachEntity pdfAttach = new AttachEntity();
                        
                        bool result = wsdoc.DocToPDF(context.Request.FilePath, downUserName,out pdfAttach);
                        if (result)
                        {
                            context.Response.Clear();
                            context.Response.ClearHeaders();
                            context.Response.ClearContent();
                            context.Response.ContentEncoding = System.Text.Encoding.GetEncoding("ISO-8859-9");
                            context.Response.ContentType = "application/" + "pdf";
                            context.Response.Charset = "windows-1254";
                            context.Response.AddHeader("Content-Length", pdfAttach.Data.Length.ToString());
                            context.Response.AddHeader("content-disposition", "attachment; filename=\"" + HttpUtility.UrlPathEncode(System.IO.Path.GetFileName(pdfAttach.FileName)) + "\"");
                            context.Response.BinaryWrite(pdfAttach.Data);
                            context.Response.Flush();
                            context.Response.End();
                        }
                        else
                        {
                            context.Response.Write("文件无效无法下载！");
                            context.Response.End();
                        }
                       
                        
                        
                        
                    }
                }
            }        }        #endregion
    }