java画图_Java实现的简单画图板示例

好的，以下是一个简单的Java画图板示例：

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

public class SimpleDraw extends JFrame implements ActionListener {
    private JButton clearBtn;
    private DrawArea drawArea;

    public SimpleDraw() {
        // 设置窗口标题
        super("Simple Draw");

        // 创建清除按钮
        clearBtn = new JButton("Clear");
        clearBtn.addActionListener(this);

        // 创建绘制区域
        drawArea = new DrawArea();

        // 将按钮和绘制区域添加到窗口中
        Container c = getContentPane();
        c.setLayout(new BorderLayout());
        c.add(clearBtn, BorderLayout.NORTH);
        c.add(drawArea, BorderLayout.CENTER);

        // 设置窗口大小
        setSize(600, 400);

        // 显示窗口
        setVisible(true);
    }

    // 处理清除按钮的点击事件
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == clearBtn) {
            drawArea.clear();
        }
    }

    // 绘制区域类
    class DrawArea extends JComponent {
        private Image image;
        private Graphics2D g2;

        public DrawArea() {
            // 添加鼠标事件监听器
            addMouseListener(new MouseAdapter() {
                public void mousePressed(MouseEvent e) {
                    // 记录鼠标按下时的坐标
                    int x = e.getX();
                    int y = e.getY();

                    // 创建新的图像对象
                    image = createImage(getSize().width, getSize().height);
                    g2 = (Graphics2D) image.getGraphics();
                    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
                    clear();
                    g2.setPaint(Color.black);
                    drawLine(x, y);
                }
            });

            // 添加鼠标事件监听器
            addMouseMotionListener(new MouseMotionAdapter() {
                public void mouseDragged(MouseEvent e) {
                    // 绘制线条
                    drawLine(e.getX(), e.getY());
                }
            });
        }

        // 绘制线条
        private void drawLine(int x, int y) {
            g2.drawLine(x, y, x, y);
            repaint();
        }

        // 清除图像
        public void clear() {
            g2.setPaint(Color.white);
            g2.fillRect(0, 0, getSize().width, getSize().height);
            g2.setPaint(Color.black);
            repaint();
        }

        // 绘制图像
        protected void paintComponent(Graphics g) {
            if (image == null) {
                image = createImage(getSize().width, getSize().height);
                g2 = (Graphics2D) image.getGraphics();
                g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
                clear();
            }
            g.drawImage(image, 0, 0, null);
        }
    }

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

这个示例实现了一个简单的画图板，可以使用鼠标在绘制区域中绘制线条，并且可以使用清除按钮清除绘制区域中的内容。