用Java实现一个网络监听程序，要求如下： 1、使用图形用户界面。有服务器和客户端，服务器监听客户端的登陆。即：如果A客户端登陆服务器，则服务器界面上的A字母对应的红灯变成绿色。绿灯表示连接，红灯表示断线。 2、可以通过图形用户界面添加新的客户机。 3、可以通过服务器进行广播 4、添加注释

以下是一个简单的Java网络监听程序的实现，满足上述要求：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class NetworkMonitor extends JFrame implements ActionListener {

    private static final long serialVersionUID = 1L;
    private static final int PORT = 1234; // 监听端口
    private JLabel serverStatus; // 服务器状态
    private JButton addButton; // 添加客户端按钮
    private JButton broadcastButton; // 广播按钮
    private JPanel clientPanel; // 客户端面板
    private ArrayList<ClientHandler> clients; // 客户端列表

    public NetworkMonitor() {
        super("网络监听程序");
        setSize(400, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // 服务器状态标签
        serverStatus = new JLabel("服务器已启动");
        add(serverStatus, BorderLayout.NORTH);

        // 添加客户端按钮
        addButton = new JButton("添加客户端");
        addButton.addActionListener(this);
        JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
        buttonPanel.add(addButton);
        add(buttonPanel, BorderLayout.SOUTH);

        // 客户端面板
        clientPanel = new JPanel();
        add(clientPanel, BorderLayout.CENTER);

        // 广播按钮
        broadcastButton = new JButton("广播");
        broadcastButton.addActionListener(this);
        add(broadcastButton, BorderLayout.EAST);

        // 客户端列表
        clients = new ArrayList<ClientHandler>();

        setVisible(true);

        // 启动服务器
        startServer();
    }

    /**
     * 启动服务器
     */
    private void startServer() {
        try {
            ServerSocket serverSocket = new ServerSocket(PORT);
            while (true) {
                Socket socket = serverSocket.accept();
                ClientHandler clientHandler = new ClientHandler(socket);
                clients.add(clientHandler);
                clientPanel.add(clientHandler.getClientPanel());
                clientPanel.revalidate();
                clientPanel.repaint();
                serverStatus.setText("客户端已连接：" + clients.size());
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 处理按钮点击事件
     */
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == addButton) {
            addClient();
        } else if (e.getSource() == broadcastButton) {
            broadcast();
        }
    }

    /**
     * 添加客户端
     */
    private void addClient() {
        ClientDialog dialog = new ClientDialog(this);
        if (dialog.showDialog()) {
            ClientHandler clientHandler = new ClientHandler(dialog.getIP(), dialog.getPort());
            clients.add(clientHandler);
            clientPanel.add(clientHandler.getClientPanel());
            clientPanel.revalidate();
            clientPanel.repaint();
            serverStatus.setText("客户端已连接：" + clients.size());
        }
    }

    /**
     * 广播消息
     */
    private void broadcast() {
        for (ClientHandler clientHandler : clients) {
            clientHandler.sendMessage("服务器广播消息");
        }
    }

    /**
     * 客户端处理类
     */
    private class ClientHandler {

        private Socket socket; // 客户端socket
        private JLabel nameLabel; // 客户端名称
        private JLabel statusLabel; // 客户端连接状态

        public ClientHandler(Socket socket) {
            this.socket = socket;
            nameLabel = new JLabel(socket.getInetAddress().getHostAddress());
            statusLabel = new JLabel("连接中");
            statusLabel.setForeground(Color.RED);
        }

        public ClientHandler(String ip, int port) {
            try {
                socket = new Socket(ip, port);
                nameLabel = new JLabel(ip + ":" + port);
                statusLabel = new JLabel("连接中");
                statusLabel.setForeground(Color.RED);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        /**
         * 获取客户端面板
         */
        public JPanel getClientPanel() {
            JPanel panel = new JPanel(new FlowLayout(FlowLayout.LEFT));
            panel.add(nameLabel);
            panel.add(statusLabel);
            return panel;
        }

        /**
         * 发送消息
         */
        public void sendMessage(String message) {
            try {
                socket.getOutputStream().write(message.getBytes());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 添加客户端对话框类
     */
    private class ClientDialog extends JFrame implements ActionListener {

        private static final long serialVersionUID = 1L;
        private JLabel ipLabel;
        private JLabel portLabel;
        private JTextField ipField;
        private JTextField portField;
        private JButton okButton;
        private JButton cancelButton;
        private boolean result;

        public ClientDialog(JFrame parent) {
            super("添加客户端");
            setLocationRelativeTo(parent);
            setSize(300, 150);
            setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

            ipLabel = new JLabel("IP地址：");
            portLabel = new JLabel("端口号：");
            ipField = new JTextField(20);
            portField = new JTextField(20);
            okButton = new JButton("确定");
            okButton.addActionListener(this);
            cancelButton = new JButton("取消");
            cancelButton.addActionListener(this);

            JPanel panel = new JPanel(new BorderLayout());
            JPanel inputPanel = new JPanel(new GridLayout(2, 2));
            inputPanel.add(ipLabel);
            inputPanel.add(ipField);
            inputPanel.add(portLabel);
            inputPanel.add(portField);
            panel.add(inputPanel, BorderLayout.CENTER);
            JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
            buttonPanel.add(okButton);
            buttonPanel.add(cancelButton);
            panel.add(buttonPanel, BorderLayout.SOUTH);

            add(panel);

            result = false;
        }

        /**
         * 显示对话框
         */
        public boolean showDialog() {
            setVisible(true);
            return result;
        }

        /**
         * 获取IP地址
         */
        public String getIP() {
            return ipField.getText();
        }

        /**
         * 获取端口号
         */
        public int getPort() {
            return Integer.parseInt(portField.getText());
        }

        /**
         * 处理按钮点击事件
         */
        public void actionPerformed(ActionEvent e) {
            if (e.getSource() == okButton) {
                result = true;
                dispose();
            } else if (e.getSource() == cancelButton) {
                result = false;
                dispose();
            }
        }
    }

    public static void main(String[] args) {
        new NetworkMonitor();
    }

}

该程序使用Java Swing构建图形用户界面，包括服务器状态标签、添加客户端按钮、客户端面板和广播按钮。通过监听端口来接受客户端连接，每个客户端连接后在客户端面板中添加一个标签，显示客户端的IP地址和连接状态。点击添加客户端按钮可以手动添加客户端，点击广播按钮可以向所有客户端发送广播消息。