how to open a locally saved file to a web browser using java

I am trying to implement a simple proxy server program in Java. How can I open the locally saved "cached" files in my computer to a web brower using Java programming language (without any frameworks or applets, all on command line). Is there really a way for me to do this? I have been searching a lot for this but still no luck. If someone knows, please show me also the code. I am using Ubuntu Linux 14.04