Download File in ASP.NET

protected void Button1_Click(object sender, EventArgs e)

{

// Get the physical Path of the file(test.doc)
string filepath = Server.MapPath("images/5.jpg");
// Create New instance of FileInfo class to get the properties of the file being downloaded
FileInfo file = new FileInfo(filepath);
// Checking if file exists
if (file.Exists)

{

// Clear the content of the response

Response.ClearContent();

Response.Clear();

// LINE1: Add the file name and attachment, which will force the open/cance/save dialog to show, to the header

Response.AddHeader(

"Content-Disposition", "attachment; filename=" + file.Name); // Add the file size into the response header

Response.AddHeader(

"Content-Length", file.Length.ToString()); // Set the ContentType

Response.ContentType = ReturnExtension(file.Extension.ToLower());

// Write the file into the response (TransmitFile is for ASP.NET 2.0. In ASP.NET 1.1 you have to use WriteFile instead)

Response.TransmitFile(file.FullName);

Response.Flush();

// End the response

Response.End();

}

}

private string ReturnExtension(string fileExtension)

{

switch (fileExtension)

{

case ".htm":

case ".html":

case ".log":

return "text/HTML";

case ".txt":

return "text/plain";

case ".doc":

return "application/ms-word";

case ".tiff":

case ".tif":

return "image/tiff";

case ".asf":

return "video/x-ms-asf";

case ".avi":

return "video/avi";

case ".zip":

return "application/zip";

case ".xls":

case ".csv":

return "application/vnd.ms-excel";

case ".gif":

return "image/gif";

case ".jpg":

case "jpeg":

return "image/jpeg";

case ".bmp":

return "image/bmp";

case ".wav":

return "audio/wav";

case ".mp3":

return "audio/mpeg3";

case ".mpg":

case "mpeg":

return "video/mpeg";

case ".rtf":

return "application/rtf";

case ".asp":

return "text/asp";

case ".pdf":

return "application/pdf";

case ".fdf":

return "application/vnd.fdf";

case ".ppt":

return "application/mspowerpoint";

case ".dwg":

return "image/vnd.dwg";

case ".msg":

return "application/msoutlook";

case ".xml":

case ".sdxl":

return "application/xml";

case ".xdp":

return "application/vnd.adobe.xdp+xml";

default:

return "application/octet-stream";

}

}