asp.net 我从数据库中（不是文件夹）下载文件，下载后内容为System.Byte[]，求帮助

Question

asp.net 我从数据库中（不是文件夹）下载文件，下载后内容为System.Byte[]，求帮助代码如下：
SqlCommand mySelect = new SqlCommand("select * FROM files where id = 1", sqlConn);
        SqlDataReader reader;
        reader = mySelect.ExecuteReader();
        if (reader.Read())
        {
            string sFileName = reader["FileName"].ToString();
            String length = reader["FileSize"].ToString();
            Response.Clear();
            Response.ClearContent();
            Response.ClearHeaders();
           
            Response.ContentEncoding = Encoding.Default;
            Response.AddHeader("Content-Disposition", "attachment; filename=" + System.Web.HttpUtility.UrlEncode(sFileName, System.Text.Encoding.UTF8).Replace("+", ""));
            Response.AppendHeader("Content-Length", length);  
            Response.ContentType = "application/octet-stream";
            
            byte[] bt = (Byte[])reader["FileData"];
            Response.OutputStream.Write(bt, 0, bt.Length);
            Response.Flush();
            
            Response.OutputStream.Close();
            Response.End();
        }

Answer 1

byte[] bt = (Byte[])reader["FileData"];
---------------------
应该就是这个转换出错了。

Answer 2

换个方式吧 private void FN_ResponseFile()
        {
            System.IO.Stream iStream = null;
            byte[] buffer = new Byte[10000];
            int length;
            long dataToRead;
            //获取资源的编号
            string id = Request["id"].ToString();
            NRBLL.File bf = new Asiastar.NRBLL.File();
            Guid guid = new Guid(id);
            //获取资源完整路径
            if (bf.FN_SerchPathByFileId(guid).Tables[0].Rows[0]["FilePath"] != null)
            {
//filepath 存的是完整路径 
                string filepath = bf.FN_SerchPathByFileId(guid).Tables[0].Rows[0]["FilePath"].ToString();
                string filename = System.IO.Path.GetFileName(filepath);                try
                {
                    string fileName = HttpUtility.UrlEncode(System.Text.Encoding.UTF8.GetBytes(filename));
                    filename = filename.Replace("+", "%20");  //将“+”替换成“空格”
                    iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read);
                    dataToRead = iStream.Length;
                    Response.ContentType = "application/octet-stream";
                    Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8));
                    while (dataToRead > 0)
                    {
                        if (Response.IsClientConnected)
                        {
                            length = iStream.Read(buffer, 0, 10000);
                            Response.OutputStream.Write(buffer, 0, length); Response.Flush();
                            buffer = new Byte[10000];
                            dataToRead = dataToRead - length;
                        }
                        else
                        {
                            dataToRead = -1;
                        }
                    }
                }
                catch (Exception)
                {
                    Response.Write("文件下载时出现错误!");
                }
                finally
                {
                    if (iStream != null)
                    {
                        iStream.Close();
                    }
                }
            }
            else
            {
                Page.RegisterStartupScript("提示", "<script type='javascript'>alert('文件不存在！')</script>");
            }
        }

Answer 3

#region 文件下载
       public bool DownLoadFile(string localPath, string hostURL, int byteCount, string userID, long cruuent)
       {
           
           bool result = true;
           
           
           string tmpURL = hostURL;
          
           byteCount = byteCount * 1024;
           hostURL = tmpURL + "&npos=" + cruuent.ToString();
           
           System.IO.FileStream fs;  
           fs = new FileStream(localPath, FileMode.OpenOrCreate);
           if (cruuent > 0)
           {
               //偏移指针
               fs.Seek(cruuent, System.IO.SeekOrigin.Current); 
           }
           System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(hostURL);
           if (cruuent > 0)
           {
               request.AddRange(Convert.ToInt32(cruuent));    //设置Range值
           }           try
           {
               //向服务器请求，获得服务器回应数据流
               System.IO.Stream ns = request.GetResponse().GetResponseStream();               byte[] nbytes = new byte[byteCount];
               int nReadSize = 0;
               nReadSize = ns.Read(nbytes, 0, byteCount);
              
               while (nReadSize > 0)
               {
                   fs.Write(nbytes, 0, nReadSize);
                   nReadSize = ns.Read(nbytes, 0, byteCount);
                  
               }
               fs.Close();
               ns.Close();
           }
           catch(Exception ex)
           {
               LOG.Error("下载" + localPath + "的时候失败！" + "原因是:" + ex.Message);
               fs.Close();
               result = false;
           }
           return result;     
       }
       #endregion