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Java· swing 小demo

news 2025/5/27 18:47:44

简单的 Java Swing 画图 Demo，包含基本的绘图功能（直线、矩形、椭圆）和颜色选择功能。这个示例代码结构清晰，适合初学者理解 Swing 绘图的基本原理

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;public class SimpleDrawingDemo {public static void main(String[] args) {// 创建并设置GUIJFrame frame = new JFrame("简易绘图工具");frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);frame.setSize(800, 600);// 创建绘图面板DrawingPanel drawingPanel = new DrawingPanel();// 创建工具栏JPanel toolPanel = new JPanel();JButton lineBtn = new JButton("直线");JButton rectBtn = new JButton("矩形");JButton ovalBtn = new JButton("椭圆");JButton clearBtn = new JButton("清除");// 添加按钮到工具栏toolPanel.add(lineBtn);toolPanel.add(rectBtn);toolPanel.add(ovalBtn);toolPanel.add(clearBtn);// 添加颜色选择器JButton colorBtn = new JButton("颜色");toolPanel.add(colorBtn);// 按钮事件监听lineBtn.addActionListener(e -> drawingPanel.setShapeType(ShapeType.LINE));rectBtn.addActionListener(e -> drawingPanel.setShapeType(ShapeType.RECTANGLE));ovalBtn.addActionListener(e -> drawingPanel.setShapeType(ShapeType.OVAL));clearBtn.addActionListener(e -> drawingPanel.clear());// 颜色选择事件colorBtn.addActionListener(e -> {Color newColor = JColorChooser.showDialog(frame, "选择颜色", drawingPanel.getColor());if (newColor != null) {drawingPanel.setColor(newColor);}});// 添加组件到窗口frame.add(toolPanel, BorderLayout.NORTH);frame.add(drawingPanel, BorderLayout.CENTER);// 显示窗口frame.setVisible(true);}
}// 绘图形状枚举
enum ShapeType {LINE, RECTANGLE, OVAL
}// 绘图形状类
class Shape {private int x1, y1, x2, y2;private Color color;private ShapeType type;public Shape(int x1, int y1, int x2, int y2, Color color, ShapeType type) {this.x1 = x1;this.y1 = y1;this.x2 = x2;this.y2 = y2;this.color = color;this.type = type;}public void draw(Graphics g) {g.setColor(color);switch (type) {case LINE:g.drawLine(x1, y1, x2, y2);break;case RECTANGLE:g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));break;case OVAL:g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));break;}}
}// 绘图面板类
class DrawingPanel extends JPanel {private ArrayList<Shape> shapes = new ArrayList<>();private ShapeType currentShapeType = ShapeType.LINE;private Color currentColor = Color.BLACK;private int startX, startY;private Shape currentShape;public DrawingPanel() {setBackground(Color.WHITE);// 添加鼠标监听器addMouseListener(new MouseAdapter() {@Overridepublic void mousePressed(MouseEvent e) {startX = e.getX();startY = e.getY();}@Overridepublic void mouseReleased(MouseEvent e) {int endX = e.getX();int endY = e.getY();shapes.add(new Shape(startX, startY, endX, endY, currentColor, currentShapeType));repaint();}});// 添加鼠标移动监听器addMouseMotionListener(new MouseMotionAdapter() {@Overridepublic void mouseDragged(MouseEvent e) {int endX = e.getX();int endY = e.getY();currentShape = new Shape(startX, startY, endX, endY, currentColor, currentShapeType);repaint();}});}@Overrideprotected void paintComponent(Graphics g) {super.paintComponent(g);// 绘制所有已保存的形状for (Shape shape : shapes) {shape.draw(g);}// 绘制当前正在绘制的形状if (currentShape != null) {currentShape.draw(g);}}public void setShapeType(ShapeType type) {this.currentShapeType = type;}public void setColor(Color color) {this.currentColor = color;}public Color getColor() {return currentColor;}public void clear() {shapes.clear();repaint();}
}