编写一个GUI界面的Socket聊天室（UDPChatGUI.java）

很高兴回答你的问题！下面是一个简单的UDP Socket聊天室的GUI界面的示例代码（UDPChatGUI.java）：

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;

public class UDPChatGUI extends JFrame {

    private JPanel contentPane;
    private JTextField txtMessage;
    private JTextArea txtChat;
    private JButton btnSend;
    private DatagramSocket socket;
    private InetAddress address;
    private int port;
    private Thread receiveThread;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    UDPChatGUI frame = new UDPChatGUI();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public UDPChatGUI() {
        setTitle("UDP Chat");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        txtChat = new JTextArea();
        txtChat.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(txtChat);
        contentPane.add(scrollPane, BorderLayout.CENTER);

        JPanel panel = new JPanel();
        contentPane.add(panel, BorderLayout.SOUTH);
        panel.setLayout(new BorderLayout(0, 0));

        txtMessage = new JTextField();
        panel.add(txtMessage, BorderLayout.CENTER);
        txtMessage.setColumns(10);

        btnSend = new JButton("Send");
        btnSend.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                sendMessage();
            }
        });
        panel.add(btnSend, BorderLayout.EAST);

        // Create a new DatagramSocket
        try {
            socket = new DatagramSocket();
        } catch (IOException e1) {
            e1.printStackTrace();
        }

        // Get the IP address and port number of the server
        try {
            address = InetAddress.getByName("localhost");
            port = 8888;
        } catch (Exception e1) {
            e1.printStackTrace();
        }

        // Start a new thread to receive messages from the server
        receiveThread = new Thread(new Runnable() {
            public void run() {
                byte[] buffer = new byte[1024];
                DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
                while (true) {
                    try {
                        socket.receive(packet);
                        String message = new String(packet.getData(), 0, packet.getLength());
                        txtChat.append("Server: " + message + "\n");
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
        receiveThread.start();
    }

    private void sendMessage() {
        try {
            // Get the message from the text field
            String message = txtMessage.getText();

            // Convert the message to bytes
            byte[] buffer = message.getBytes();

            // Create a new DatagramPacket
            DatagramPacket packet = new DatagramPacket(buffer, buffer.length, address, port);

            // Send the packet
            socket.send(packet);

            // Append the message to the chat window
            txtChat.append("Me: " + message + "\n");

            // Clear the text field
            txtMessage.setText("");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

这个程序使用了Java的Swing GUI库，创建了一个简单的聊天室界面，包括一个文本框和一个发送按钮。当用户点击发送按钮时，程序将文本框中的消息发送到服务器，并将其显示在聊天窗口中。程序还启动了一个单独的线程来接收来自服务器的消息，并将它们显示在聊天窗口中。

请注意，这个示例程序仅用于演示目的，不能直接在生产环境中使用，因为它缺乏安全性和错误处理。在实际应用中，您需要更多的代码来处理异常情况，如网络连接中断、数据包丢失等。