java创建一个Turtle实现 Turtle Graphics API 的功能

Java可以通过创建一个Turtle类实现Turtle Graphics API的功能。下面是一个简单的实现示例：

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.util.ArrayList;

public class Turtle {
  private Point position;
  private double angle;
  private boolean penDown;
  private Color penColor;
  private ArrayList<Point> path;

  public Turtle() {
    position = new Point(0, 0);
    angle = 0;
    penDown = true;
    penColor = Color.BLACK;
    path = new ArrayList<>();
  }

  public void draw(Graphics g) {
    g.setColor(penColor);

    for (int i = 0; i < path.size() - 1; i++) {
      Point p1 = path.get(i);
      Point p2 = path.get(i + 1);

      g.drawLine(p1.x, p1.y, p2.x, p2.y);
    }
  }

  public void penDown(boolean down) {
    penDown = down;
  }

  public void setPenColor(Color color) {
    penColor = color;
  }

  public void forward(double distance) {
    double newX = position.x + distance * Math.cos(Math.toRadians(angle));
    double newY = position.y + distance * Math.sin(Math.toRadians(angle));

    Point newPoint = new Point((int) newX, (int) newY);

    if (penDown) {
      path.add(position);
      path.add(newPoint);
    }

    position = newPoint;
  }

  public void turn(double degrees) {
    angle += degrees;
  }

  public void setPosition(int x, int y) {
    position = new Point(x, y);
  }
}

该类包含了笔的位置、方向、颜色等属性，以及前进、旋转、设置位置等方法，可以实现良好的绘图效果。