使用Java写一个小烟花

以下是一个简单的 Java 烟花动画示例代码，使用了 JavaFX 库：

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.effect.BlendMode;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class Fireworks extends Application {

    private static final int WIDTH = 800;
    private static final int HEIGHT = 600;

    private static final int MAX_PARTICLES = 1000;
    private static final double GRAVITY = 0.2;

    private static final Random random = new Random();

    private final List<Particle> particles = new ArrayList<>();

    private GraphicsContext gc;
    private Canvas canvas;
    private AnimationTimer timer;

    @Override
    public void start(Stage primaryStage) {
        canvas = new Canvas(WIDTH, HEIGHT);

        gc = canvas.getGraphicsContext2D();

        Group root = new Group();
        root.getChildren().add(canvas);

        Scene scene = new Scene(root, WIDTH, HEIGHT, Color.BLACK);

        primaryStage.setTitle("Fireworks");
        primaryStage.setScene(scene);
        primaryStage.show();

        timer = new AnimationTimer() {
            @Override
            public void handle(long now) {
                update();
                draw();
            }
        };
        timer.start();
    }

    private void update() {
        if (particles.size() < MAX_PARTICLES) {
            particles.add(new Particle(WIDTH / 2, HEIGHT, random.nextDouble() * 2 * Math.PI));
        }

        for (int i = 0; i < particles.size(); i++) {
            Particle particle = particles.get(i);

            if (particle.isDead()) {
                particles.remove(i--);
            } else {
                particle.update();
            }
        }
    }

    private void draw() {
        gc.setGlobalBlendMode(BlendMode.SRC_OVER);
        gc.setFill(Color.BLACK);
        gc.fillRect(0, 0, WIDTH, HEIGHT);

        for (Particle particle : particles) {
            particle.draw(gc);
        }
    }

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

    private static class Particle {

        private static final int MAX_LIFE = 60;

        private double x;
        private double y;
        private double vx;
        private double vy;
        private int life;

        private final Color color;

        public Particle(double x, double y, double angle) {
            this.x = x;
            this.y = y;
            this.vx = Math.cos(angle) * 5;
            this.vy = Math.sin(angle) * 5;
            this.life = MAX_LIFE;
            this.color = Color.hsb(random.nextDouble() * 360, 1, 1);
        }

        public void update() {
            x += vx;
            y -= vy;
            vy -= GRAVITY;
            life--;
        }

        public boolean isDead() {
            return life <= 0;
        }

        public void draw(GraphicsContext gc) {
            gc.setFill(color);
            gc.fillOval(x, y, 2, 2);
        }

    }

}

这个示例代码会在窗口中随机生成烟花，每个烟花会发射出若干个颜色随机的小粒子，看起来像是一朵烟花在绽放。