Restrict user to directly call an excel file by typing URL in browser address

[jonesy]

Hi,

I have a java servlet which on authentication redirects an Excel file.
But I found the URL of the Excel file can be directly pasted in the
browser address bar and then also the file can be directly downloaded
without authentication.

eg. I would like to restrict user from directly downloading the Excel
file by entering the URL www.mysite.com/my/download/data.xls in IE
address bar.

The code below is what I am currently playing trial-and-error with. I
would really appreciate any suggestions of whether I'm on the right
track or not. I have a feeling I need to use DataOutputStream
somewhere, but I'm really not sure.

Any code, directions, help or suggestions would be great! Thanks


Code:

DataInputStream dis = null;

byte[] buffer = new byte[0];

try
{
File f = new
File("./myserver/website_files/otherfiles/excelFile.xls");

if (f.length() == 0)
{
//error handling
}

if (f.list() != null)
{
//error handling
}

FileInputStream fis = new FileInputStream(f);
BufferedInputStream bis = new BufferedInputStream(fis);
dis = new DataInputStream(bis);

dis.readFully(buffer);
}
catch (IOException e)
{
//error handling
}
finally
{
// if the file opened okay, make sure we close it
if (dis != null)
{
try
{
dis.close();
}
catch (IOException ioe)
{
}
}
}