写一段贪食蛇的Java代码

以下是一个简单的贪食蛇Java代码示例：

import java.util.ArrayList;
import java.util.Random;
import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.Label;
import javafx.scene.input.KeyCode;
import javafx.scene.layout.BorderPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class SnakeGame extends Application {
    private static final int WIDTH = 400;
    private static final int HEIGHT = 400;
    private static final int TILE_SIZE = 10;
    private static final Color SNAKE_COLOR = Color.GREEN;
    private static final Color FOOD_COLOR = Color.RED;
    private static final Random rand = new Random();

    private ArrayList<Position> snake;
    private Position food;
    private Direction direction;
    private boolean gameOver = false;

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

    @Override
    public void start(Stage stage) {
        Canvas canvas = new Canvas(WIDTH, HEIGHT);
        GraphicsContext gc = canvas.getGraphicsContext2D();
        Label scoreLabel = new Label("Score: 0");

        BorderPane root = new BorderPane(canvas, null, null, scoreLabel, null);
        Scene scene = new Scene(root, WIDTH, HEIGHT);

        // Initialize game
        snake = new ArrayList<>();
        snake.add(new Position(WIDTH / 2, HEIGHT / 2));
        spawnFood();
        direction = Direction.NONE;

        // Handle input
        scene.setOnKeyPressed(e -> {
            if (e.getCode() == KeyCode.UP && direction != Direction.DOWN) {
                direction = Direction.UP;
            } else if (e.getCode() == KeyCode.DOWN && direction != Direction.UP) {
                direction = Direction.DOWN;
            } else if (e.getCode() == KeyCode.LEFT && direction != Direction.RIGHT) {
                direction = Direction.LEFT;
            } else if (e.getCode() == KeyCode.RIGHT && direction != Direction.LEFT) {
                direction = Direction.RIGHT;
            }
        });

        // Game loop
        new AnimationTimer() {
            private long lastUpdate = 0;
            private int score = 0;

            @Override
            public void handle(long now) {
                if (now - lastUpdate >= 100_000_000) { // Update every 100ms
                    gc.setFill(Color.WHITE);
                    gc.fillRect(0, 0, WIDTH, HEIGHT);

                    // Move snake
                    if (!gameOver) {
                        moveSnake();
                    }

                    // Draw snake
                    gc.setFill(SNAKE_COLOR);
                    for (Position pos : snake) {
                        gc.fillRect(pos.getX(), pos.getY(), TILE_SIZE, TILE_SIZE);
                    }

                    // Draw food
                    gc.setFill(FOOD_COLOR);
                    gc.fillRect(food.getX(), food.getY(), TILE_SIZE, TILE_SIZE);

                    // Check for collision with food
                    if (snake.get(0).equals(food)) {
                        snake.add(new Position(-TILE_SIZE, -TILE_SIZE)); // Add new segment off-screen
                        spawnFood();
                        score++;
                        scoreLabel.setText("Score: " + score);
                    }

                    // Check for collision with walls or self
                    if (snake.get(0).getX() < 0 || snake.get(0).getX() >= WIDTH ||
                            snake.get(0).getY() < 0 || snake.get(0).getY() >= HEIGHT ||
                            checkCollisionWithSelf()) {
                        gameOver = true;
                        gc.setFill(Color.BLACK);
                        gc.fillText("Game Over!", WIDTH / 2 - 30, HEIGHT / 2);
                    }

                    lastUpdate = now;
                }
            }
        }.start();

        stage.setScene(scene);
        stage.setTitle("Snake Game");
        stage.show();
    }

    private void moveSnake() {
        // Move each segment of the snake
        for (int i = snake.size() - 1; i > 0; i--) {
            snake.get(i).setX(snake.get(i - 1).getX());
            snake.get(i).setY(snake.get(i - 1).getY());
        }

        // Move head of snake in correct direction
        if (direction == Direction.UP) {
            snake.get(0).setY(snake.get(0).getY() - TILE_SIZE);
        } else if (direction == Direction.DOWN) {
            snake.get(0).setY(snake.get(0).getY() + TILE_SIZE);
        } else if (direction == Direction.LEFT) {
            snake.get(0).setX(snake.get(0).getX() - TILE_SIZE);
        } else if (direction == Direction.RIGHT) {
            snake.get(0).setX(snake.get(0).getX() + TILE_SIZE);
        }
    }

    private void spawnFood() {
        // Choose a random position for the food
        int x = rand.nextInt(WIDTH / TILE_SIZE) * TILE_SIZE;
        int y = rand.nextInt(HEIGHT / TILE_SIZE) * TILE_SIZE;
        food = new Position(x, y);

        // Make sure food doesn't spawn on top of snake
        while (checkCollisionWithSelf()) {
            x = rand.nextInt(WIDTH / TILE_SIZE) * TILE_SIZE;
            y = rand.nextInt(HEIGHT / TILE_SIZE) * TILE_SIZE;
            food.setX(x);
            food.setY(y);
        }
    }

    private boolean checkCollisionWithSelf() {
        // Check if any part of the snake is on top of the food
        for (Position pos : snake) {
            if (pos.equals(food)) {
                return true;
            }
        }

        // Check if any part of the snake is colliding with itself
        for (int i = 1; i < snake.size(); i++) {
            if (snake.get(0).equals(snake.get(i))) {
                return true;
            }
        }

        return false;
    }
}

class Position {
    private int x;
    private int y;

    public Position(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof Position) {
            Position other = (Position) obj;
            return x == other.x && y == other.y;
        }

        return false;
    }
}

enum Direction {
    UP, DOWN, LEFT, RIGHT, NONE
}

该代码使用JavaFX库实现了一个简单的贪食蛇游戏。其中包含Snake类、Position类和Direction枚举类。Snake类包含主要的游戏逻辑，Position类用于表示游戏中的位置，Direction枚举类用于表示蛇头移动的方向。代码使用Canvas和GraphicsContext绘制游戏界面，并使用AnimationTimer进行游戏循环。整个游戏的逻辑比较简单，可以通过阅读代码来理解。