从页面点击下载，数据库中下载数据（格式可能是音频，视频），页面出现保存路径的框体

Question

      string filePath = "F:\\娱乐\\;//设置保存路径 
            byte[] file = null;             SqlConnection conn = new SqlConnection(); 
            conn.ConnectionString = "server=server;database=archives; user id=sa;password=123"; 
            conn.Open();         
            string sql = "select file_content from  multimedia ";             SqlCommand cm = new SqlCommand(); 
            cm.CommandText = sql; 
            cm.CommandType = CommandType.Text; 
            cm.Connection = conn; 
            SqlDataReader dr = cm.ExecuteReader();             while (dr.Read()) 
            { 
                if (dr["file_content"].ToString() != "") 
                {                     file = (byte[])dr["file_content"];                 } 
｝ 
  自己写的代码可以下载，但不提示保存对话框，新人敬请高人，小分相送，谢谢

Answer 1

http://www.cnblogs.com/bear-study-hard/archive/2006/03/09/346154.html

Answer 2

public class DownloadHandler : IHttpHandler
    {
        /// <summary>
        ///功能说明：文件下载类--不管是什么格式的文件,都能够弹出打开/保存窗口,
        ///包括使用下载工具下载
        ///继承于IHttpHandler接口，可以用来自定义HTTP 处理程序同步处理HTTP的请求
        /// </summary>
        /// <param name="context"></param>
        public void ProcessRequest(HttpContext context)
        {
            HttpResponse Response = context.Response;
            HttpRequest Request = context.Request;            System.IO.Stream iStream = null;            byte[] buffer = new Byte[10240];            int length;            long dataToRead;            try
            {
                string filename = FileHelper.Decrypt(Request["fn"]); //通过解密得到文件名                string filepath = HttpContext.Current.Server.MapPath("~/") + filename; //待下载的文件路径                iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open,
                    System.IO.FileAccess.Read, System.IO.FileShare.Read);
                Response.Clear();                dataToRead = iStream.Length;                long p = 0;
                if (Request.Headers["Range"] != null)
                {
                    Response.StatusCode = 206;
                    p = long.Parse(Request.Headers["Range"].Replace("bytes=", "").Replace("-", ""));
                }
                if (p != 0)
                {
                    Response.AddHeader("Content-Range", "bytes " + p.ToString() + "-" + ((long)(dataToRead - 1)).ToString() + "/" + dataToRead.ToString());
                }
                Response.AddHeader("Content-Length", ((long)(dataToRead - p)).ToString());
                Response.ContentType = "application/octet-stream";
                Response.AddHeader("Content-Disposition", "attachment; filename=" + System.Web.HttpUtility.UrlEncode(System.Text.Encoding.GetEncoding(65001).GetBytes(Path.GetFileName(filename))));                iStream.Position = p;
                dataToRead = dataToRead - p;                while (dataToRead > 0)
                {
                    if (Response.IsClientConnected)
                    {
                        length = iStream.Read(buffer, 0, 10240);                        Response.OutputStream.Write(buffer, 0, length);
                        Response.Flush();                        buffer = new Byte[10240];
                        dataToRead = dataToRead - length;
                    }
                    else
                    {
                        dataToRead = -1;
                    }
                }
            }
            catch (Exception ex)
            {
                Response.Write("Error : " + ex.Message);
            }
            finally
            {
                if (iStream != null)
                {
                    iStream.Close();
                }
                Response.End();
            }
        }        public bool IsReusable
        {
            get { return true; }
        }
    }    public class FileHelper
    {
        /// <summary>
        /// 利用Base64码对文件名进行加密处理。
        /// </summary>
        /// <param name="filename">文件名</param>
        /// <returns></returns>
        public static string Encrypt(string filename)
        {
            byte[] buffer = HttpContext.Current.Request.ContentEncoding.GetBytes(filename);
            return HttpUtility.UrlEncode(Convert.ToBase64String(buffer));
        }        /// <summary>
        /// 利用Base64码对文件名进行解密处理。
        /// </summary>
        /// <param name="encryptfilename">文件名</param>
        /// <returns></returns>
        public static string Decrypt(string encryptfilename)
        {
            byte[] buffer = Convert.FromBase64String(encryptfilename);
            return HttpContext.Current.Request.ContentEncoding.GetString(buffer);
        }    }
web.config设置:   <httpHandlers>
    <add verb="*" path="download.aspx" type="命名空间.DownloadHandler"/>
   </httpHandlers>//前台页面:        protected void Button1_Click(object sender, EventArgs e)
        {
            string url = FileHelper.Encrypt("下载文件");
            Response.Redirect("~/download.aspx?fn=" + url);//解密下载
        }