文件下载功能

代码如下：

/// <summary>/// 附件下载/// </summary>/// <param name="attachId">附件ID</param>public void DownloadAttach(int attachId){    Edu_Attach edu_Attach = edu_AttachService.findById<Edu_Attach>(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();        }    }}