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Editorial Team
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Asked: 2026-05-30T08:40:18+00:00

I have an applet that needs to submit a score to a servlet and

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I have an applet that needs to submit a score to a servlet and it is not working correctly.

This is the code for the applet

private URLConnection getConnection() throws MalformedURLException, IOException {
        URL serverAddress = null;
        URLConnection conn = null;
        serverAddress = new URL("http://localhost/GamesPortal/submitScore");
        conn = serverAddress.openConnection();
        conn.setDoOutput(true);
        conn.setRequestProperty("Content-Type", "application/x-java-serialized-object");
        return conn;
    }

    private void sendRecievedata(GameInfo info) {
        try {
            URLConnection c = this.getConnection();
            OutputStream os =  c.getOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(os);
            oos.writeObject(info);
            oos.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

And this is the servlet code

    try {
        HttpSession s = request.getSession(true);

        response.setContentType("application/x-java-serialized-object");
        InputStream in = request.getInputStream();
        ObjectInputStream ois = new ObjectInputStream(in);
        GameInfo info = (GameInfo) ois.readObject();

        if (info.getUserId() > 0) {
            Scores score = new Scores();
            score.submitScore(info);
        }
    } catch (Exception ex) {
        ex.printStackTrace();
    } finally {
    }
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter();
    try {
        out.println("<html>");
        out.println("<head>");
        out.println("<title>Servlet submitScore</title>");            
        out.println("</head>");
        out.println("<body>");
        out.println("<h1>Servlet submitScore at " + request.getContextPath() + "</h1>");
        out.println("</body>");
        out.println("</html>");
    } catch {
        ex.printStackTrace();
    } finally {            
        out.close();
    }

Now I have tried accessing the servlet via the browser, just to make sure that the address is correct (it is), but for some reason when I try to access it from the applet itself, it does not connect. (the debugger does not even launch).

(added the ex.printStackTrace(); to each of the try catches, as per suggestion, but I have no idea what or where I’m supposed to look for this)

The code calling the applet looks similar to this:
http://roseindia.net/jsp/simple-jsp-example/applet-in-jsp.shtml

<jsp:plugin code="Pong.class" name="Games/Pong/Pong" type="applet" width="800" height="600">
    <jsp:params>
        <jsp:param name="userId" value="<%= user.getUserId()%>" ></jsp:param>
    </jsp:params>
</jsp:plugin>

Is there something that I am overlooking here?

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1 Answer

  1. Editorial Team

    I have managed to make it work.

    This is the code for the applet:

        private URLConnection getServletConnection()
        throws MalformedURLException, IOException {
    URL urlServlet = new URL("http://localhost:8080/GamePortal/submitScore");
    URLConnection con = urlServlet.openConnection();
    con.setDoOutput(true);
    con.setRequestProperty(
            "Content-Type",
            "application/x-java-serialized-object");
    return con;

}

private void onSendData(GameInfo info) {

    try {
        // send data to the servlet
        URLConnection con = getServletConnection();
        OutputStream outstream = con.getOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(outstream);
        oos.writeObject(info);
        oos.flush();
        oos.close();
        // receive result from servlet
        InputStream instr = con.getInputStream();
        ObjectInputStream inputFromServlet = new ObjectInputStream(instr);
        String result = (String) inputFromServlet.readObject();
        //JOptionPane.showMessageDialog(null, result);
        inputFromServlet.close();
        instr.close();
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

    This is the code for the servlet:

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {        
    try {
        response.setContentType("application/x-java-serialized-object");
        // read a String-object from applet
        // instead of a String-object, you can transmit any object, which
        // is known to the servlet and to the applet
        InputStream in = request.getInputStream();
        ObjectInputStream inputFromApplet = new ObjectInputStream(in);
        GameInfo score = (GameInfo) inputFromApplet.readObject();
        System.out.println(score.getScore());

        GameInfo info = score;

        if (info.getUserId() > 0) {
            Scores instance = new Scores();
            instance.submitScore(info);
        }

        OutputStream outstr = response.getOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(outstr);
        oos.writeObject("reply");
        oos.flush();
        oos.close();
    } catch (ClassNotFoundException ex) {
    }
}

    Thanks for your help and forgive me for taking too long to reply.

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