用Java语言编写一个GUI界面的Socket聊天室，具体要求:界面要求服务器端有退出，关闭功能，显示“开始监听9999端口！”客户端有发送，清空功能，显示“连接到127.0.0.1:9999端口”

好的，我可以帮你回答这个问题。首先，我们需要使用Java的GUI库来实现界面，比如Swing或JavaFX。其次，我们需要使用Socket编程实现聊天室的功能。以下是一个简单的实现：

服务器端：

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class ChatServer {
    private ServerSocket serverSocket;
    private Thread serverThread;

    public ChatServer(int port) {
        try {
            serverSocket = new ServerSocket(port);
            System.out.println("开始监听" + port + "端口！");
            start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void start() {
        serverThread = new Thread(() -> {
            try {
                while (true) {
                    Socket socket = serverSocket.accept();
                    System.out.println("有客户端连接到服务器：" + socket.getRemoteSocketAddress());
                    new ChatServerThread(socket).start();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        });
        serverThread.start();
    }

    public void stop() {
        try {
            serverSocket.close();
            serverThread.interrupt();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        ChatServer server = new ChatServer(9999);
        // 等待用户输入"exit"命令退出
        while (true) {
            String command = System.console().readLine();
            if ("exit".equals(command)) {
                server.stop();
                break;
            }
        }
    }
}

客户端：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class ChatClient extends JFrame {
    private static final long serialVersionUID = 1L;
    private static final String SERVER_HOST = "127.0.0.1";
    private static final int SERVER_PORT = 9999;

    private Socket socket;
    private BufferedReader reader;
    private PrintWriter writer;

    private JPanel panel;
    private JTextArea textArea;
    private JTextField textField;
    private JButton sendButton;
    private JButton clearButton;

    public ChatClient() {
        initUI();
        initSocket();
    }

    private void initUI() {
        setTitle("聊天室");
        setSize(400, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        panel = new JPanel();
        getContentPane().add(panel);

        textArea = new JTextArea();
        textArea.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(textArea);
        scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
        panel.add(scrollPane);

        textField = new JTextField(20);
        panel.add(textField);

        sendButton = new JButton("发送");
        sendButton.addActionListener(e -> {
            String message = textField.getText();
            if (!message.isEmpty()) {
                writer.println(message);
                writer.flush();
                textField.setText("");
            }
        });
        panel.add(sendButton);

        clearButton = new JButton("清空");
        clearButton.addActionListener(e -> {
            textArea.setText("");
        });
        panel.add(clearButton);
    }

    private void initSocket() {
        try {
            socket = new Socket(SERVER_HOST, SERVER_PORT);
            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            writer = new PrintWriter(socket.getOutputStream(), true);
            System.out.println("连接到" + SERVER_HOST + ":" + SERVER_PORT + "端口");
            new ChatClientThread().start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private class ChatClientThread extends Thread {
        @Override
        public void run() {
            try {
                while (true) {
                    String message = reader.readLine();
                    if (message == null) {
                        break;
                    }
                    textArea.append(message + "\n");
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    reader.close();
                    writer.close();
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    public static void main(String[] args) {
        ChatClient client = new ChatClient();
        client.setVisible(true);
    }
}

以上代码实现了一个简单的GUI界面的Socket聊天室，界面包含发送和清空按钮，服务器端可以退出和关闭，客户端可以连接到指定的主机和端口。