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java如何实现画板

2026-03-23 06:36:24Java

使用 Java Swing 实现画板

Java Swing 提供了丰富的图形界面组件，可以用于实现一个简单的画板功能。以下是一个基本的实现方法：

创建主窗口

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

public class DrawingBoard extends JFrame {
    private int lastX, lastY;
    private Color currentColor = Color.BLACK;

    public DrawingBoard() {
        setTitle("Java 画板");
        setSize(800, 600);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel drawingPanel = new JPanel() {
            {
                addMouseMotionListener(new MouseMotionAdapter() {
                    public void mouseDragged(MouseEvent e) {
                        Graphics g = getGraphics();
                        g.setColor(currentColor);
                        g.drawLine(lastX, lastY, e.getX(), e.getY());
                        lastX = e.getX();
                        lastY = e.getY();
                    }
                });

                addMouseListener(new MouseAdapter() {
                    public void mousePressed(MouseEvent e) {
                        lastX = e.getX();
                        lastY = e.getY();
                    }
                });
            }
        };

        add(drawingPanel, BorderLayout.CENTER);

        JPanel controlPanel = new JPanel();
        JButton clearButton = new JButton("清除");
        clearButton.addActionListener(e -> drawingPanel.repaint());

        JButton colorButton = new JButton("颜色");
        colorButton.addActionListener(e -> {
            currentColor = JColorChooser.showDialog(null, "选择颜色", currentColor);
        });

        controlPanel.add(clearButton);
        controlPanel.add(colorButton);
        add(controlPanel, BorderLayout.SOUTH);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            new DrawingBoard().setVisible(true);
        });
    }
}

使用 JavaFX 实现画板

JavaFX 提供了更现代的 UI 框架，以下是使用 JavaFX 实现的画板示例：

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.Button;
import javafx.scene.control.ColorPicker;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class FXDrawingBoard extends Application {
    private double lastX, lastY;
    private Color currentColor = Color.BLACK;

    @Override
    public void start(Stage primaryStage) {
        Canvas canvas = new Canvas(800, 550);
        GraphicsContext gc = canvas.getGraphicsContext2D();
        gc.setStroke(currentColor);
        gc.setLineWidth(2);

        canvas.setOnMousePressed(e -> {
            lastX = e.getX();
            lastY = e.getY();
        });

        canvas.setOnMouseDragged(e -> {
            gc.strokeLine(lastX, lastY, e.getX(), e.getY());
            lastX = e.getX();
            lastY = e.getY();
        });

        ColorPicker colorPicker = new ColorPicker(currentColor);
        colorPicker.setOnAction(e -> {
            currentColor = colorPicker.getValue();
            gc.setStroke(currentColor);
        });

        Button clearButton = new Button("清除");
        clearButton.setOnAction(e -> gc.clearRect(0, 0, canvas.getWidth(), canvas.getHeight()));

        HBox controls = new HBox(10, colorPicker, clearButton);
        BorderPane root = new BorderPane(canvas, null, null, controls, null);

        primaryStage.setScene(new Scene(root));
        primaryStage.setTitle("JavaFX 画板");
        primaryStage.show();
    }

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