Should not use System.exit(0) in servlet.

I would suggest you to read this first 

[About servlets in StackOverflow](https://stackoverflow.com/questions/4005873/using-jsp-to-download-a-file)

Then here is a file downloading example by BalusC

[Serve your files](http://balusc.blogspot.in/2007/07/fileservlet.html)

Once you understand the concepts, you can fly with servlets. All the best.