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Editorial Team
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Asked: 2026-05-23T04:32:18+00:00

I’m trying to connect from a standalone applet to a servlet running on tomcat:

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I’m trying to connect from a standalone applet to a servlet running on tomcat:

Servlet

public void init(ServletConfig config) throws ServletException { 
    super.init(config);
    // Start a daemon thread 
    try { 
        daemonThread = new Daemon(this);
        daemonThread.start();
    }
    catch (Exception e) { 
    }
}

protected int getSocketPort() { 
    return 8080;
}

public void handleClient(Socket client){ 
    new ScribbleThread(this, client).start();
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) 
throws ServletException, IOException {
    PrintWriter out = response.getWriter();
    StringBuffer sb = new StringBuffer();
    sb.append("<html><body bgcolor=pink text=red>");
    sb.append("<h1 align=center>RUNNING</h1><hr>");
    sb.append("</body></html>");
    out.println(sb);
    out.close();
}
}

Servlet’s init() creates this:

class Daemon extends Thread { 
private ServerSocket serverSocket;
private SocketServlet servlet;

public Daemon(SocketServlet servlet) { 
this.servlet = servlet;
}

public void run() { 
    try { 
        // Create a server socket to accept connections 
        serverSocket = new ServerSocket(servlet.getSocketPort());
    }
    catch (Exception e) { 
        return;
    }
    try { 
        while (true) { 
            try { 
                servlet.handleClient(serverSocket.accept());
            }
            catch (IOException ioe) { 
            }
        }
    }

I have this deployed by eclipse to TomCat. My question is what address does my applet need to make the socket to? When i visit http://localhost:8080/scrabServ/connect I see the ‘RUNNING’ message from the doGet() so is that where it needs to point?

Applet:

public static String testConnection(){
    InputStream in = null; 
    try { 
        // Make socket connection to servlet
        String servlet = new String("localhost/scrabServ/connect");
        Socket socket = new Socket(servlet, 8080);

this gives me:

Exception in testConnection()java.net.UnknownHostException: localhost/scrabServ/connect
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:195)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:432)
at java.net.Socket.connect(Socket.java:529)
at java.net.Socket.connect(Socket.java:478)
at java.net.Socket.<init>(Socket.java:375)
at java.net.Socket.<init>(Socket.java:189)
at scribble.Scribble.testConnection(Scribble.java:41)
at scribble.Scribble.main(Scribble.java:28)

and points to the new Socket(servlet, 8080) line.

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1 Answer

  1. Editorial Team

    You would have only to open a socket to "localhost", 8080 and then issue a GET scrabServ/connect command. You can’t open a socket to a specific URL.

    To communicate with a servlet you do it via request parameters, basically issuing a GET command such as: http://www.jmarshall.com/easy/http/http_footnotes.html#getsubmit

    Maybe you should use URLConnection instead. If you detail what exactly you want to do, maybe I can have a better idea of how to help you, maybe a HTTP server is not even needed for what you want to do.

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