用JavaSocket编程实现带图形界面的白板程序的代码

以下是一个简单的基于Java Socket编程的带图形界面的白板程序的代码：

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import javax.swing.*;

public class Whiteboard extends JFrame implements ActionListener {

    private JButton connectButton, clearButton, colorButton;
    private JLabel statusLabel;
    private JPanel canvasPanel;
    private JTextField hostField, portField;
    private String host;
    private int port;
    private Graphics2D g2d;
    private Color color = Color.BLACK;
    private Socket socket;
    private ObjectOutputStream out;
    private ObjectInputStream in;
    private boolean connected = false;

    public Whiteboard() {
        super("Whiteboard");

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        connectButton = new JButton("Connect");
        connectButton.addActionListener(this);
        clearButton = new JButton("Clear");
        clearButton.addActionListener(this);
        colorButton = new JButton("Color");
        colorButton.addActionListener(this);

        statusLabel = new JLabel("Not connected");

        hostField = new JTextField("localhost", 10);
        portField = new JTextField("8000", 4);

        JPanel controlPanel = new JPanel();
        controlPanel.add(connectButton);
        controlPanel.add(clearButton);
        controlPanel.add(colorButton);
        controlPanel.add(new JLabel("Host:"));
        controlPanel.add(hostField);
        controlPanel.add(new JLabel("Port:"));
        controlPanel.add(portField);
        controlPanel.add(statusLabel);

        canvasPanel = new JPanel() {
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g2d = (Graphics2D) g;
            }
        };
        canvasPanel.setPreferredSize(new Dimension(600, 400));
        canvasPanel.setBackground(Color.WHITE);
        canvasPanel.addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent e) {
                if (connected) {
                    try {
                        out.writeObject(new Point(e.getX(), e.getY()));
                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
                }
            }
        });
        canvasPanel.addMouseMotionListener(new MouseAdapter() {
            public void mouseDragged(MouseEvent e) {
                if (connected) {
                    try {
                        out.writeObject(new Point(e.getX(), e.getY()));
                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
                }
                g2d.setColor(color);
                g2d.drawLine(e.getX(), e.getY(), e.getX(), e.getY());
                canvasPanel.repaint();
            }
        });

        getContentPane().add(canvasPanel, BorderLayout.CENTER);
        getContentPane().add(controlPanel, BorderLayout.SOUTH);

        pack();
        setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == connectButton) {
            host = hostField.getText();
            port = Integer.parseInt(portField.getText());
            connect();
        } else if (e.getSource() == clearButton) {
            clear();
        } else if (e.getSource() == colorButton) {
            color = JColorChooser.showDialog(this, "Choose a color", color);
        }
    }

    public void connect() {
        try {
            socket = new Socket(host, port);
            out = new ObjectOutputStream(socket.getOutputStream());
            in = new ObjectInputStream(socket.getInputStream());
            connected = true;
            statusLabel.setText("Connected");
            new Thread(new ReceiveThread()).start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void clear() {
        g2d.setColor(Color.WHITE);
        g2d.fillRect(0, 0, canvasPanel.getWidth(), canvasPanel.getHeight());
        canvasPanel.repaint();
        if (connected) {
            try {
                out.writeObject("clear");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public void receive(Point p) {
        g2d.setColor(color);
        g2d.drawLine(p.x, p.y, p.x, p.y);
        canvasPanel.repaint();
    }

    class ReceiveThread implements Runnable {
        public void run() {
            try {
                while (true) {
                    Object obj = in.readObject();
                    if (obj instanceof Point) {
                        receive((Point) obj);
                    } else if (obj instanceof String) {
                        if (obj.equals("clear")) {
                            clear();
                        }
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    }

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

这个程序创建了一个带有连接、清除和颜色选择按钮和一个绘图区域的窗口，可以通过Socket连接到另一个Whiteboard程序，然后在两个程序之间共享绘图。连接成功后，用户可以在绘图区域上绘制，这些绘图会被发送到另一个Whiteboard程序，并在其绘图区域上显示。用户可以使用清除按钮删除所有绘图，可以使用颜色选择器选择不同的颜色来绘制。