java画图_Java实现的简单画图板示例

好的，下面是一个简单的 Java 画图板示例：

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

public class SimplePaint extends JFrame implements ActionListener, MouseListener, MouseMotionListener {
    private JButton clearBtn, blackBtn, blueBtn, greenBtn, redBtn;
    private JLabel mousePos;
    private JPanel drawPanel;
    private int prevX, prevY, currX, currY;

    public SimplePaint() {
        super("Simple Paint");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // 创建按钮
        clearBtn = new JButton("Clear");
        blackBtn = new JButton("Black");
        blueBtn = new JButton("Blue");
        greenBtn = new JButton("Green");
        redBtn = new JButton("Red");

        // 设置按钮监听器
        clearBtn.addActionListener(this);
        blackBtn.addActionListener(this);
        blueBtn.addActionListener(this);
        greenBtn.addActionListener(this);
        redBtn.addActionListener(this);

        // 创建面板
        JPanel btnPanel = new JPanel();
        btnPanel.add(clearBtn);
        btnPanel.add(blackBtn);
        btnPanel.add(blueBtn);
        btnPanel.add(greenBtn);
        btnPanel.add(redBtn);

        mousePos = new JLabel("Mouse position: ");

        drawPanel = new JPanel();
        drawPanel.setBackground(Color.white);
        drawPanel.addMouseListener(this);
        drawPanel.addMouseMotionListener(this);

        add(btnPanel, BorderLayout.NORTH);
        add(mousePos, BorderLayout.SOUTH);
        add(drawPanel, BorderLayout.CENTER);

        setSize(600, 400);
        setVisible(true);
    }

    // 按钮事件处理
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == clearBtn) {
            Graphics g = drawPanel.getGraphics();
            g.setColor(Color.white);
            g.fillRect(0, 0, drawPanel.getWidth(), drawPanel.getHeight());
        } else if (e.getSource() == blackBtn) {
            drawPanel.setForeground(Color.black);
        } else if (e.getSource() == blueBtn) {
            drawPanel.setForeground(Color.blue);
        } else if (e.getSource() == greenBtn) {
            drawPanel.setForeground(Color.green);
        } else if (e.getSource() == redBtn) {
            drawPanel.setForeground(Color.red);
        }
    }

    // 鼠标事件处理
    public void mousePressed(MouseEvent e) {
        prevX = e.getX();
        prevY = e.getY();
    }

    public void mouseDragged(MouseEvent e) {
        currX = e.getX();
        currY = e.getY();
        Graphics g = drawPanel.getGraphics();
        g.drawLine(prevX, prevY, currX, currY);
        prevX = currX;
        prevY = currY;
    }

    public void mouseClicked(MouseEvent e) {
        mousePos.setText("Mouse position: " + e.getX() + ", " + e.getY());
    }

    public void mouseMoved(MouseEvent e) {
        mousePos.setText("Mouse position: " + e.getX() + ", " + e.getY());
    }

    public void mouseEntered(MouseEvent e) {}

    public void mouseExited(MouseEvent e) {}

    public void mouseReleased(MouseEvent e) {}

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

这个简单的画图板示例包含了颜色选择、清除以及鼠标事件处理等基本功能。你可以根据自己的需求进行修改和扩展。