Open secure Sharepoint file programmatically using c# - sharepoint

Question

I need help opening am online Sharepoint file programmatically. These files need to be secured on Sharepoint (so that users can't wander into them), but I also need to access it somehow using my webpart (which will check for security). Normally, you can just use a hyperlink that links to the Sharepoint file, but we don't want people sharing these hyperlinks, so that won't work.
I want the user to click a link, and have them see the "Open, Save, Close" dialog menu for that file.
I have tried this
String fileName = #"file.txt";
String filePath = #"~online filePath/";
System.Web.HttpResponse response = System.Web.HttpContext.Current.Response;
response.ClearHeaders();
response.ClearContent();
response.Clear();
response.ContentType = "text/plain";
//or whatever file type, I can code that later
response.AddHeader("Content-Disposition", "attachment; Filename=" + fileName + ";");
response.TransmitFile(filePath + fileName);
//response.Flush();
response.End();
Unfortunately, while this works fine for local files (C://...), when I try this on my web fike, I only receive a text document that has the source code for the current page. Not sure why.
As for dealing with the permissions, I plan to use elevated priviledges to have the program gain access to the files.
I would appreciate any help, Thanks.

Answer 1

Here is sample code to provide a file for download with SharePoint
using (SPWeb web = SPContext.Current.Web)
{
//Get fileName and filePath here
response.AddHeader("Content-disposition", "attachment; filename=" + fileName);
response.ContentType = "application/octet-stream";
SPFile file = web.GetFile(filePath);
byte[] fileBytes = file.OpenBinary();
response.OutputStream.Write(fileBytes, 0, fileBytes.Length);
response.End();
}
Does this help or are you having problems locating the fileName and filePath?