/**
   * Responds to HTTP GET requests.
   *
   * @param request the HTTPServletRequest object
   * @param response the HttpServletResponse object
   *
   * @throws ServletException
   * @throws IOException
   */
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException
  {
    //The query string sent by the client tells which button was clicked
    // on the Web page.
    String query = request.getQueryString();

    // Read the current state of the LEDs (0=on, 1=off).
    // and toggle the LED named in the query string.
    boolean led1On;
    if ("button1".equals(query)) {
      System.out.println("Button 1 was clicked");

      // Toggle the LED.
      led1On = toggle(led1);
    } else {

      // Don't toggle the LED.
      // Read the LED's state and set led1On true if the state is 0
      // (on) and false if the state is 1 (off).
      led1On = (led1.readLatch() == 0);
    }

    boolean led2On;
    if ("button2".equals(query)) {
      System.out.println("Button 2 was clicked");

      // Toggle the LED.
      // A logic low turns the LED on.
      led2On = toggle(led2);
    } else {

      // Don't toggle the LED.
      // Read the LED's state and set led2On true if the state is 0
      // (on) and false if the state is 1 (off).
      led2On = (led2.readLatch() == 0);
    }

    // Set the images and text to match the current LEDs' states
    // If led1State (led2State) is true, LED1 (LED2) is off.
    // If led2State (led2State) is false, LED1 (LED2) is on.
    String led1Image;
    String led1State;
    if (led1On) {
      led1Image= "/ledon.gif";
      led1State = "on";
    }
    else {
      led1Image = "/ledoff.gif";
      led1State = "off";
    }

    String led2Image;
    String led2State;
    if (led2On) {
      led2Image= "/ledon.gif";
      led2State = "on";
    }
    else {
      led2Image = "/ledoff.gif";
      led2State = "off";
    }

    // Return the Web page to the client.
    SendWebPage (response, led1Image, led2Image,
                 led1State, led2State);

  } //end doGet
      
      Listing 2. The servlet’s doGet() method services HTTP requests for the Web page.