代码如下：

/// 
/// 附件下载/// 
/// 附件IDpublic void DownloadAttach(int attachId){    Edu_Attach edu_Attach = edu_AttachService.findById
      
       (attachId);    if (edu_Attach != null)    {        HttpContext context = (HttpContext)ctx.web.Context;        if (context != null)        {            string filePathName = PathHelper.Map(sys.Path.DiskPhoto) + edu_Attach.AttachContent.Replace("/static/upload/image", "").Replace("/", "\\");            int pos = filePathName.LastIndexOf("\\");            string fileName = filePathName.Substring(pos + 1);            string UserAgent = context.Request.ServerVariables["http_user_agent"].ToLower();            if (UserAgent.IndexOf("firefox") == -1)            {                //非火狐浏览器                context.Response.AddHeader("content-disposition", "attachment;filename=" + HttpUtility.UrlEncode(edu_Attach.AttachName));            }            else            {                context.Response.AddHeader("content-disposition", "attachment;filename=" + edu_Attach.AttachName);            }            FileStream fs = new FileStream(filePathName, FileMode.Open, FileAccess.Read);            byte[] bArr = new byte[fs.Length];            fs.Read(bArr, 0, bArr.Length);            fs.Close();            context.Response.ContentEncoding = Encoding.UTF8;            context.Response.BinaryWrite(bArr);            context.Response.Flush();            context.Response.End();        }    }}