File file = new File("pfad_zur_datei_auf_dem_server");
response.setContentLength( length_of_file );
response.setContentType("application/x-file-download");
response.setHeader("Content-disposition",
"attachment; filename="
+ file.getName());
response.setHeader("Cache-Control",
"max-age=" + MAX_AGE_IN_SECONDS);
ServletOutputStream out = response.getOutputStream();
InputStream in = new FileInputStream( file );
byte[] buffer = new byte[512];
int n = 0;
while ( ( n = in.read(buffer)) != -1)
{
out.write(buffer, 0, n);
}
in.close();
out.flush();