要实现画图板功能，可以使用Java的Swing库来创建一个简单的绘图应用。以下是一个基本的示例代码，用于实现画图板功能：

import javax.swing.*;import java.awt.*;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.MouseAdapter;import java.awt.event.MouseEvent;public class DrawingBoard extends JFrame {private int startX, startY, endX, endY;private Color currentColor = Color.BLACK;public DrawingBoard() {setTitle("Drawing Board");setSize(800, 600);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);JPanel controlPanel = new JPanel();JButton redButton = new JButton("Red");redButton.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {currentColor = Color.RED;}});JButton blackButton = new JButton("Black");blackButton.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {currentColor = Color.BLACK;}});controlPanel.add(redButton);controlPanel.add(blackButton);JPanel drawingPanel = new JPanel() {@Overrideprotected void paintComponent(Graphics g) {super.paintComponent(g);g.setColor(currentColor);g.drawLine(startX, startY, endX, endY);}};drawingPanel.addMouseListener(new MouseAdapter() {@Overridepublic void mousePressed(MouseEvent e) {startX = e.getX();startY = e.getY();}@Overridepublic void mouseReleased(MouseEvent e) {endX = e.getX();endY = e.getY();drawingPanel.repaint();}});getContentPane().add(controlPanel, BorderLayout.NORTH);getContentPane().add(drawingPanel, BorderLayout.CENTER);}public static void main(String[] args) {SwingUtilities.invokeLater(new Runnable() {@Overridepublic void run() {DrawingBoard drawingBoard = new DrawingBoard();drawingBoard.setVisible(true);}});}}

此代码创建了一个简单的绘图板应用程序，用户可以在画板上绘制直线，并可以选择绘制的颜色。用户可以使用鼠标按下并拖动来绘制线条。您可以根据需要扩展此示例代码，以实现更复杂的绘图功能，如绘制不同形状、使用不同的画笔风格等。