使用java写出绘图板代码

好的，以下是一个简单的Java绘图板代码，它可以绘制基本图形、修改颜色等功能。你可以参考它进行修改和扩展：

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

public class DrawingBoard extends JFrame implements ActionListener, MouseListener, MouseMotionListener {
    private JMenuBar mb;
    private JMenu m;
    private JMenuItem mi1, mi2, mi3, mi4, mi5;
    private JPanel p;
    private Graphics g;
    private int x1, y1, x2, y2;

    public DrawingBoard() {
        setTitle("Drawing Board");
        setSize(600, 600);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        mb = new JMenuBar();
        m = new JMenu("Options");
        mi1 = new JMenuItem("Line");
        mi2 = new JMenuItem("Rectangle");
        mi3 = new JMenuItem("Oval");
        mi4 = new JMenuItem("Clear");
        mi5 = new JMenuItem("Color");
        mi1.addActionListener(this);
        mi2.addActionListener(this);
        mi3.addActionListener(this);
        mi4.addActionListener(this);
        mi5.addActionListener(this);
        m.add(mi1);
        m.add(mi2);
        m.add(mi3);
        m.add(mi4);
        m.add(mi5);
        mb.add(m);
        setJMenuBar(mb);
        p = new JPanel();
        add(p);
        p.addMouseListener(this);
        p.addMouseMotionListener(this);
        setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == mi1) {
            g.setColor(Color.BLACK);
        } else if (e.getSource() == mi2) {
            g.setColor(Color.RED);
        } else if (e.getSource() == mi3) {
            g.setColor(Color.BLUE);
        } else if (e.getSource() == mi4) {
            p.repaint();
        } else if (e.getSource() == mi5) {
            Color c = JColorChooser.showDialog(this, "Choose Color", g.getColor());
            g.setColor(c);
        }
    }

    public void mouseClicked(MouseEvent e) {
    }

    public void mouseEntered(MouseEvent e) {
    }

    public void mouseExited(MouseEvent e) {
    }

    public void mousePressed(MouseEvent e) {
        x1 = e.getX();
        y1 = e.getY();
    }

    public void mouseReleased(MouseEvent e) {
        x2 = e.getX();
        y2 = e.getY();
        if (g != null) {
            if (mi1.isSelected()) {
                g.drawLine(x1, y1, x2, y2);
            } else if (mi2.isSelected()) {
                g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
            } else if (mi3.isSelected()) {
                g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
            }
        }
    }

    public void mouseDragged(MouseEvent e) {
        x2 = e.getX();
        y2 = e.getY();
        if (g != null) {
            if (mi1.isSelected()) {
                g.drawLine(x1, y1, x2, y2);
                x1 = x2;
                y1 = y2;
            } else if (mi2.isSelected()) {
                p.repaint();
                g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
            } else if (mi3.isSelected()) {
                p.repaint();
                g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
            }
        }
    }

    public void mouseMoved(MouseEvent e) {
    }

    public void paint(Graphics g) {
        super.paint(g);
        this.g = p.getGraphics();
    }

    public static void main(String[] args) {
        DrawingBoard db = new DrawingBoard();
    }
}

这个绘图板可以绘制直线、矩形、椭圆形，并且可以选择颜色和清除画布。你可以尝试运行这段代码，看看效果。