Tic Tac Toe in a Java Servlet

Write a servlet that displays a 3x3 grid: at the beginning, the 9 cells in the grid are buttons, and these buttons are replaced by O or X as the game progresses. Have a message indicating the winner when there is a winner, or indicating a draw when there is no possible win, and a link to restart the game.

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protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
       response.setContentType("text/html;charset=UTF-8");
      
       // we need to use session in this case
       HttpSession session = request.getSession();
       // setup some varialbe
       String [][] game = null; // game matrix
       String player = "X"; // player
      
       // get the current gamre from session
       if (session.getAttribute("game") != null) {
            game = (String[][]) session.getAttribute("game");            
       } else {
            // init it if it isn't there
            game = new String[3][3];
            for (int i = 0; i < 3; i++) {
                for (int j = 0; j < 3; j++) {
                   game[i][j] = "";
                }
            }
       }...