在Java GUI中的SwingWorker中运行ServerSocket

Question

I have been trying for a very long time to get the following code to work, with no success. I would like to open a ServerSocket and have it run in the back ground of my GUI interface. I have a start button that is supposed to start the server and a stop button that will stop the server from listening any further for clients that wish to connect.

This is a very basic GUI that has 2 buttons and 2 text fields. The user is required to input a user name and a password that is matched against a database. If the details are correct the Server should start. This however causes the GUI to freeze if the server is not run on a separate Thread. I wish to use SwingWorker to do this. (Unless there is a better way)

I however am a little in the deep end of my knowledge concerning this matter. Any help will be very appreciated. Thanks!

public class Server extends JFrame implements ActionListener {

JLabel instructionsLabel;
JLabel passwordLabel;
JPasswordField passwordTF;
JButton shutdownButton;
JButton startupButton;
JLabel usernameLabel;
JTextField usernameTF;

public Server() {
    super("Server");
    initComponents();
}



public void actionPerformed(ActionEvent e) {
    Object source = e.getSource();

    String f = "n";
    ConnectionBean cb = new ConnectionBean();

    char[] a = passwordTF.getPassword();
    String b = new String(a);
    String inputDetails = usernameTF.getText() + b;

    Iterator it = cb.getDetails().iterator();
    while (it.hasNext()) {
        Object next = it.next();
        if (inputDetails.equals(next)) {
            f = "y";
            if (source == startupButton) {
                try {
                    sop.doInBackground();
                } catch (Exception ex) {
                }
                JOptionPane.showMessageDialog(null,
                        "Congratulations! Server started.",
                        "Start-up Message",
                        JOptionPane.INFORMATION_MESSAGE);
            } else if (source == shutdownButton) {
                try {
                    sop.failIfInterrupted();
                } catch (Exception ex) {
                }
                JOptionPane.showMessageDialog(null,
                        "Server shut-down successfully!",
                        "Shut-down Message",
                        JOptionPane.INFORMATION_MESSAGE);
            }
        }
    }
    if (f.equals("n")) {
        JOptionPane.showMessageDialog(null, "Invalid username or password.", "Alert", JOptionPane.WARNING_MESSAGE);
    }
    passwordTF.setText("");
    usernameTF.setText("");
    cb.setCloseConnection(true);
}

// THIS IS WHERE I GET STUCK!

public class ServerOperation extends SwingWorker<Void, Void> {

    ServerSocket ss;
    Socket cs;

    public ServerOperation(ServerSocket ss) {
        this.ss = ss;
    }

    @Override
    protected Void doInBackground() throws Exception {

        return Void;
    }

    public void failIfInterrupted() throws InterruptedException {
        if (Thread.currentThread().isInterrupted()) {
            throw new InterruptedException();
        }
    }
}

The code that I used before, to start the server was this...

ServerSocket ss;
Socket cs;

public void StartingSer() throws Exception {

    ss = new ServerSocket(7777);

    while (true) {
        cs = ss.accept();
        new ServerTread(cs).start();

    }
}

but this causes the GUI to freeze, because it is not thread safe.

Answer 1

"but this causes the GUI to freeze, because it is not thread safe"

No, this causes the GUI to freeze because this method is executed on the GUI thread. You must use a separate thread for it.

When the Start button is pressed, create a thread, save the reference to it, and start it. When the Stop button is pressed, send interruption signal to that thread. That's it. No SwingWorker is needed.