从文件流下载文件

Question

I have a field in database of type image which stores the file in binary format.

Now I want to give a facility to user from where the user can downlaod that file. I have the file data in byte array object. How can I display the open save dialoge box to user?

Answer 1

This is an example to show blob images from the database, you can modify it to offer the file for download instead of showing the image (id is the image file id in the database):

void  CreateImage(string id)
{
    // Connection string is taken from web.config file.
    SqlConnection _con = new SqlConnection(
      System.Configuration.ConfigurationSettings.AppSettings["DB"]);

    try
    {
        _con.Open();
        SqlCommand _cmd = _con.CreateCommand();
        _cmd.CommandText = "select logo from" + 
                           " pub_info where pub_id='" + 
                           id + "'";
        byte[] _buf = (byte[])_cmd.ExecuteScalar();

        // This is optional
        Response.ContentType = "image/gif";

        //stream it back in the HTTP response
        Response.BinaryWrite(_buf);


    }
    catch
    {}
    finally
    {
        _con.Close();

    }
}

Answer 2

尝试看一下：创建ashx文件处理程序，提供带有标头的图像：

Content-Type: application/force-download

Answer 3

What about:

//using System.Net;   
WebClient wc = new WebClient();

OpenFileDialog ofd = new OpenFileDialog();
if(ofd.ShowDialog() == DialogResult.OK)
   wc.DownloadFile("http://website.net/image.jpg", ofd.FileName);

EDIT:

//using System.IO;
MemoryStream ms = new MemoryStream(array);
Bitmap bmp = new Bitmap(ms);
bmp.Save("C:\\image.bmp");