JAVA可以用windowBuilder写的多人聊天室，代码

以下是使用Java和WindowBuilder构建多人聊天室的示例代码：

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
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;
import javax.swing.border.EmptyBorder;

public class MultiChatServer extends JFrame {

    private JPanel contentPane;
    private JTextArea textArea;
    private JTextField textField;
    private JButton btnSend;
    private ServerSocket serverSocket;
    private int port = 9001;

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

    public MultiChatServer() {
        setTitle("Multi Chat Server");
        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);

        textArea = new JTextArea();
        JScrollPane scrollPane = new JScrollPane(textArea);
        contentPane.add(scrollPane, BorderLayout.CENTER);

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

        textField = new JTextField();
        panel.add(textField);
        textField.setColumns(30);

        btnSend = new JButton("Send");
        btnSend.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String message = textField.getText();
                sendToAll(message);
            }
        });
        panel.add(btnSend);

        setVisible(true);

        try {
            serverSocket = new ServerSocket(port);
            while (true) {
                Socket socket = serverSocket.accept();
                new Thread(new ClientHandler(socket)).start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void sendToAll(String message) {
        textArea.append("[Server] " + message + "\n");
        for (ClientHandler handler : ClientHandler.clients) {
            handler.sendMessage(message);
        }
    }

    private class ClientHandler implements Runnable {
        private Socket socket;
        private BufferedReader in;
        private PrintWriter out;
        private static final String DELIMITER = "> ";

        public static final String END_SESSION = "END_SESSION";

        private static final String JOIN_MESSAGE = " joined the chat.";
        private static final String EXIT_MESSAGE = " left the chat.";

        private static final String WELCOME_MESSAGE = "Welcome to the chat room!";
        private static final String DISCONNECTED_MESSAGE = "You have been disconnected from the chat room.";

        private static final String ERROR_MESSAGE = "An error occurred. Please try again later.";

        private static final String USERNAME_PROMPT_MESSAGE = "Please enter your username:";

        private String username;

        private static final int MAX_USERNAME_LENGTH = 20;

        public static final int MAX_MESSAGE_LENGTH = 200;

        public static final int MAX_CONNECTIONS = 10;

        public static final int READ_TIMEOUT = 1000;

        public static final int WRITE_TIMEOUT = 1000;

        public static final int CONNECT_TIMEOUT = 1000;

        public static final int DISCONNECT_TIMEOUT = 1000;

        public static final int SERVER_PORT = 9001;

        public static final String SERVER_ADDRESS = "localhost";

        public static final String CHARSET = "UTF-8";

        public static final int BUFFER_SIZE = 1024;

        public static final int BACKLOG = 50;

        public static final int MAX_RETRIES = 10;

        public static final int RETRY_DELAY = 100;

        public static final int MAX_USERNAME_RETRIES = 3;

        public static final int USERNAME_RETRY_DELAY = 100;

        public static final String HELP_MESSAGE = "Type /help to see this message again.\n"
                + "Type /quit to quit the chat.\n" + "Type /users to see the list of online users.\n"
                + "Type /msg [username] [message] to send a private message to a user.\n";

        public static final String QUIT_COMMAND = "/quit";
        public static final String USERS_COMMAND = "/users";
        public static final String MSG_COMMAND = "/msg";
        public static final String HELP_COMMAND = "/help";

        private static int idGenerator = 0;
        private int id;

        private static final String MSG_DELIMITER = " ";

        public static final String USERNAME_TAKEN_MESSAGE = "Sorry, that username is already taken. Please try another.";

        private static final String INVALID_COMMAND_MESSAGE = "Invalid command. Type /help for a list of commands.";

        private static final String PRIVATE_MESSAGE_PREFIX = "[Private message from ";

        private static final String PRIVATE_MESSAGE_SUFFIX = "] ";

        private static final String USERNAME_CHANGE_COMMAND = "/username";

        private static final String USERNAME_CHANGE_SUCCESS_MESSAGE = "Your username has been changed to ";

        private static final String USERNAME_CHANGE_FAILURE_MESSAGE = "Sorry, your username could not be changed. Please try again later.";

        private static final String USERNAME_CHANGE_PROMPT_MESSAGE = "Please enter your new username:";

        private static final String USERNAME_CHANGE_DELIMITER = " ";

        private static final String USERNAME_CHANGE_COMMAND_PATTERN = "^\\/username\\s.+";

        public ClientHandler(Socket socket) {
            this.socket = socket;
            id = idGenerator++;
            try {
                in = new BufferedReader(new InputStreamReader(socket.getInputStream(), CHARSET));
                out = new PrintWriter(socket.getOutputStream(), true);
                sendMessage(USERNAME_PROMPT_MESSAGE);
                for (int i = 0; i < MAX_USERNAME_RETRIES; i++) {
                    String input = readLineWithTimeout(READ_TIMEOUT);
                    if (input != null && input.length() <= MAX_USERNAME_LENGTH) {
                        username = input.trim();
                        if (isUsernameUnique(username)) {
                            sendMessage(WELCOME_MESSAGE);
                            broadcast(JOIN_MESSAGE);
                            clients.add(this);
                            break;
                        } else {
                            sendMessage(USERNAME_TAKEN_MESSAGE);
                        }
                    } else {
                        sendMessage(ERROR_MESSAGE);
                    }
                }
                if (username == null) {
                    disconnect();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        private boolean isUsernameUnique(String username) {
            for (ClientHandler handler : clients) {
                if (handler.username == null) {
                    continue;
                }
                if (handler.username.equals(username)) {
                    return false;
                }
            }
            return true;
        }

        private void broadcast(String message) {
            for (ClientHandler handler : clients) {
                if (handler == this) {
                    continue;
                }
                handler.sendMessage(message);
            }
        }

        private void sendMessage(String message) {
            out.println(message);
        }

        @Override
        public void run() {
            try {
                while (true) {
                    String input = readLineWithTimeout(READ_TIMEOUT);
                    if (input == null) {
                        continue;
                    }
                    if (input.equals(QUIT_COMMAND)) {
                        break;
                    }
                    if (input.startsWith(MSG_COMMAND)) {
                        handlePrivateMessage(input);
                    } else if (input.equals(USERS_COMMAND)) {
                        handleUsersCommand();
                    } else if (input.equals(HELP_COMMAND)) {
                        sendMessage(HELP_MESSAGE);
                    } else if (input.matches(USERNAME_CHANGE_COMMAND_PATTERN)) {
                        handleUsernameChange(input);
                    } else {
                        broadcast(username + DELIMITER + input);
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                disconnect();
            }
        }

        private void handlePrivateMessage(String input) {
            String[] tokens = input.split(MSG_DELIMITER);
            if (tokens.length < 3) {
                sendMessage(INVALID_COMMAND_MESSAGE);
                return;
            }
            String recipient = tokens[1];
            String message = input.substring(MSG_COMMAND.length() + recipient.length() + 2);
            for (ClientHandler handler : clients) {
                if (handler.username == null) {
                    continue;
                }
                if (handler.username.equals(recipient)) {
                    String privateMessage = PRIVATE_MESSAGE_PREFIX + username + PRIVATE_MESSAGE_SUFFIX + message;
                    handler.sendMessage(privateMessage);
                    sendMessage(privateMessage);
                    return;
                }
            }
            sendMessage("User " + recipient + " is not online.");
        }

        private void handleUsersCommand() {
            StringBuilder builder = new StringBuilder();
            builder.append("Online users:\n");
            for (ClientHandler handler : clients) {
                if (handler.username != null) {
                    builder.append(handler.username + "\n");
                }
            }
            sendMessage(builder.toString());
        }

        private void handleUsernameChange(String input) {
            String newUsername = input.substring(USERNAME_CHANGE_COMMAND.length() + 1);
            if (!isUsernameUnique(newUsername)) {
                sendMessage(USERNAME_TAKEN_MESSAGE);
                return;
            }
            String oldUsername = username;
            username = newUsername;
            broadcast(oldUsername + " changed their username to " + newUsername + ".");
            sendMessage(USERNAME_CHANGE_SUCCESS_MESSAGE + newUsername + ".");
        }

        private void disconnect() {
            clients.remove(this);
            try {
                in.close();
                out.close();
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            broadcast(EXIT_MESSAGE);
            sendMessage(DISCONNECTED_MESSAGE);
        }

        private String readLineWithTimeout(int timeout) throws IOException {
            socket.setSoTimeout(timeout);
            StringBuilder builder = new StringBuilder();
            char[] buffer = new char[BUFFER_SIZE];
            int charsRead = 0;
            while (true) {
                int charsReadThisTime = in.read(buffer, 0, BUFFER_SIZE);
                if (charsReadThisTime == -1) {
                    break;
                }
                builder.append(buffer, 0, charsReadThisTime);
                charsRead += charsReadThisTime;
                if (builder.toString().endsWith("\n")) {
                    break;
                }
            }
            if (charsRead > 0) {
                return builder.toString().trim();
            } else {
                return null;
            }
        }
    }

}

这段代码使用了Java的Socket和ServerSocket实现了一个简单的聊天室服务器，可以让多个客户端连接并交换消息。该代码使用了WindowBuilder图形界面构建工具，因此具有可视化的用户界面。