在Java中单击按钮时启动和停止服务器

Question

I have a server class that runs and stops a server for my android app to connect to. It works fine when just using is from the terminal. But I want to make it a GUI so i don't have to launch it from anything else. And to keep a better output on it.

Heres my Main.java:

public class Main {
    public static void main(String[] args) throws Exception {
        Form f = new Form();
        f.setVisible(true);
    }
}

Form.java UPDATED:

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Form extends JFrame {
    private JTextArea outputArea;
    private JButton button;

    private Server server; // Created a new Server instance
    private Thread t;      // Created a new Thread instance

    public Form() {
        initComponents();
        server = new Server(); // Initialized server
    }

    private void initComponents() {
        outputArea = new JTextArea();
        button = new JButton();

        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setTitle("Home Server");
        setSize(400, 350);
        setResizable(false);
        setLocationRelativeTo(null);

        button.setText("Start Server");
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                DoSomething();
            }
        });

        outputArea.setSize(400, 350);
        outputArea.setEditable(false);

        Container pane = getContentPane();
        GroupLayout gl = new GroupLayout(pane);
        pane.setLayout(gl);

        gl.setAutoCreateContainerGaps(true);

        gl.setHorizontalGroup(gl.createSequentialGroup()
            .addComponent(button)
        );

        gl.setVerticalGroup(gl.createSequentialGroup()
            .addComponent(button)
        );

        pack();
    }

    private void DoSomething() {
        if (!server.isRunning()) {
            t = new Thread(server); // Initialized thread.
            t.start();

            button.setText("Stop Server");
        } else {
            t.interrupt();

            button.setText("Start Server");
        }
    }
}

Server.java UPDATED (Removed static references):

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.*;
import java.util.Enumeration;

public class Server implements Runnable {
    private static ServerSocket serverSocket = null;
    private static Socket socket = null;
    private static DataInputStream dataInputStream = null;
    private static DataOutputStream dataOutputStream = null;

    private static int port = 19586;

    private static boolean running = false;

    public void Start() {
        try {
            System.out.println("Starting Server...");

            serverSocket = new ServerSocket(port);

            System.out.println("Server Started");
            System.out.println("IP Address: " + getIpAddress());
            System.out.println("Listening: " + serverSocket.getLocalPort());

            running = true;
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            System.out.println("Attempting to connect to clients...");
            socket = serverSocket.accept();

            dataInputStream = new DataInputStream(socket.getInputStream());
            dataOutputStream = new DataOutputStream(socket.getOutputStream());

            System.out.println("ip: " + socket.getInetAddress());
            System.out.println("message: " + dataInputStream.readUTF());

            dataOutputStream.writeUTF("connected");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void Stop() {
        if (running) {
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            if (dataInputStream != null) {
                try {
                    dataInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            if (dataOutputStream != null) {
                try {
                    dataOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            running = false;
        }
    }

    private String getIpAddress() {
        String ip = "";
        try {
            Enumeration<NetworkInterface> enumNetworkInterfaces = NetworkInterface.getNetworkInterfaces();
            while (enumNetworkInterfaces.hasMoreElements()) {
                NetworkInterface networkInterface = enumNetworkInterfaces.nextElement();
                Enumeration<InetAddress> enumInetAddress = networkInterface.getInetAddresses();
                while (enumInetAddress.hasMoreElements()) {
                    InetAddress inetAddress = enumInetAddress.nextElement();

                    if (inetAddress.isSiteLocalAddress()) {
                        ip += "SiteLocalAddress: " + inetAddress.getHostAddress();
                    }
                }
            }

        } catch (SocketException e) {
            e.printStackTrace();
            ip += "Something Wrong! " + e.toString() + "\n";
        }

        return ip;
    }

    public boolean isRunning() {
        return running;
    }

    public void run() {
        while (!Thread.interrupted()) {
            Start();
        }
    }
}

Im sure its a simple fix, but I just can't get it to terminate the server. I tried different methods and everything. I know that if I just call Server.Start(); on the button press that it will use the current thread to start the server, and thats not what I want.

It will start, but Im not sure if it ever stops or not.

Answer 1

You are starting your server on the UI thread... Not a great idea. To fix, you need to create another Thread

Either implement a Runnable or override Thread.run()

Runnable r = new Runnable () {
  public void run() {
    Server.Start();
  }
}
new Thread(r).start();

Answer 2

In your DoSomething method (which should be capitalized as doSomething), you are always creating a new Server, and you are not keeping a reference to it.

So, every time the button is clicked, you start a new server.

You'll need to keep a reference to the server, and only start a new one if the reference is null. Same problem with the Thread.

I wouldn't make the isRunning method in Server static, either.

Answer 3

You could use a MouseListener since your class there extends JFrame. MouseListener has 5 methods that go along with it. mousePressed, mouseClicked, mouseReleased, mouseEntered, and mouseExited.

Every one of those explains themselves with their name, except for mousePressed and mouseClicked (sort of).

mousePressed is invoked whenever ANY button on the mouse is clicked. mouseClicked is invoked when you LEFT CLICK the component (in your case the JFrame ) that is being listened to.