How to return many HTML files together in Java servlet response?

I have a few html files each of them containing the components of my future web page. I want them to be shown if user was looking for them. But how can I show many html files together in servlet response? As I know, the code below can redirect user to only one html file.

RequestDispatcher rd = request.getRequestDispatcher("/index.html");
rd.forward(request, response);
response.sendRedirect("/index.html");

I tried to use IO streams:

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    List<String> content = new ArrayList<String>();
    BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream("/header.html")));
    while ((str = in.readLine()) != null) {
        content.add(str);
    }
    PrintWriter out = response.getWriter();
    for (String item: content) {
        out.println(item);
    }
}

But it gives me only java.io.FileNotFoundException:header.html. Browser says: "HTTP Status 500 - Internal Server Error". How can I solve this? Should use another way?