如何下载 listbox里显示的文件(数据库已绑定了)

上传文件实现的代码

protected void Unnamed1_Click(object sender, EventArgs e)
 {


 if (FileUpload1.PostedFile.FileName == string.Empty)
 {
 Response.Write("<script>alert('请选择要上传的文件！');</script>");
 }
 else
 {
 //获取要上传的文件的信息
 string filepath = FileUpload1.PostedFile.FileName;//文件路径
 string oldfilename = filepath.Substring(filepath.LastIndexOf("\\")+1);//文件名
 string FileExtension = Path.GetExtension(oldfilename); //文件的扩展名
 int filelength = (int)oldfilename.Length;//文件名长度
 //随机生成文件名
 Random Rnd = new Random();
 int strRnd = Rnd.Next(1, 99);
 string newfilename = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() + strRnd.ToString() + FileExtension.ToLower();
 //将文件上传到以当前日期命名的文件夹中
 string UpLoadName = DateTime.Now.Year.ToString()+"-"+DateTime.Now.Month.ToString()+"-"+DateTime.Now.Day.ToString();
 bool FileUploadPathExists = File.Exists(Server.MapPath("UpLoad"+"\\"+UpLoadName));
 //指定文件夹不存在，如果不存在就创建该文件夹
 if (!FileUploadPathExists)
 {
 Directory.CreateDirectory(Server.MapPath("UpLoad"+"\\"+UpLoadName));
 }
 //保存上传的文件
 string savapath = Server.MapPath("UpLoad" + "\\" + UpLoadName);//保存路径
 string savapath1 = "UpLoad" + "\\" + UpLoadName +"\\"+ newfilename;//保存路径
 FileUpload1.PostedFile.SaveAs(savapath + "\\" + newfilename);
 //连接数据库字符串
 string connStr = @"Data Source=.;AttachDbFilename=D:\1\Solution2\App_Data\Database.mdf;Integrated Security=True;User Instance=false";
 SqlConnection conn = new SqlConnection(connStr);
 conn.Open();

 string cmdtext = "insert into T_UpFile(FileName,FileLength,FileType,FilePath) values('" + newfilename + "','" + filelength + "','" + FileExtension + "','"+savapath1+"')";
 SqlCommand cmd = new SqlCommand(cmdtext, conn);
 try
 {
 cmd.ExecuteNonQuery();
 System.Text.StringBuilder strMsg = new System.Text.StringBuilder();
 strMsg.Append(" 成功添加，详细信息： ");
 strMsg.Append("文件类型：" + this.FileUpload1.PostedFile.ContentType.ToString() + " ");
 strMsg.Append("文件名：" + filepath + " ");
 strMsg.Append("存处文件名：" + newfilename + " ");
 //strMsg.Append("文件上传到服务器的路径为：" + savapath + " ");
 strMsg.Append("扩展名：" + FileExtension + " ");
 strMsg.Append("大小：" + FileUpload1.PostedFile.ContentLength + "个字节");
 this.Label1.Text = strMsg.ToString();
 }
 catch (Exception error)
 {
 Response.Write(error.ToString());
 }
 finally
 {
 conn.Close();
 }
 }
 }} upload

补充：.NET技术 ,  C#