Question

I’m having a problem with my applet. I have a school project where I’m supposed to make a pong-online game. It runs fine offline but when I try to load it from a server I just get an empty frame with a red text in it. when I click the text I get the message:

incompatible magic value 1013478509

I’m using jetty-all-8.1.8.v20121106.jar, and servlet-api-3.0.jar

The class that starts up the server looks like this:

public class TheServer extends HttpServlet {
    private static final long serialVersionUID = 1L; 
    private Scanner sc;
    private String webSite;
    private PrintWriter out;


    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html; charset=UTF-8");
        resp.setStatus(HttpServletResponse.SC_OK);
        out = resp.getWriter();

        sc = new Scanner(new File("F:\\Users\\Johan\\Workspace Kurs 5\\PongOnline\\bin\\pong.html"));
        webSite = "";
        while(sc.hasNext())
            webSite += sc.nextLine();
        sc.close();

        out.println(webSite);
        System.out.println(webSite);
    }

    public static void main(String...args) throws Exception {
        ServletContextHandler context = new ServletContextHandler( ServletContextHandler.SESSIONS);
        context.addServlet(TheServer.class, "/");

        Server server = new Server(666);
        server.setHandler(context);
        server.start();
        server.join();
    }
}

Answer 1

According to the Java Language Specification, a proper .class file has starts with the magic number :

The magic item supplies the magic number identifying the class file
format; it has the value 0xCAFEBABE.

If you open any compiled .class file with a hex editor and inspect its first bytes, they should be 0xCAFEBABE. 1013478509 in ASCII translates to <htm.

Make sure you’ve got the class properly compiled on the server. And more likely, as BalusC already pointed out in his answer, make sure URL’s are correct. The <htm… bytes you’re getting might be an HTML error document served by the server.