给代码加注释class Canvas extends JComponent private static final long serialVersionUID = 1L; protected void paintComponentGraphics g superpaintComponentg; Graphics2D g2 = Graphics2D

// 创建一个名为Canvas的类，继承自JComponent类 class Canvas extends JComponent { // 序列版本号，用于反序列化时的版本一致性验证 private static final long serialVersionUID = 1L;

// 重写父类的paintComponent方法，用于绘制组件的外观
protected void paintComponent(Graphics g)
{
    // 调用父类的paintComponent方法，确保组件的外观能够正确绘制
    super.paintComponent(g);
    
    // 将Graphics对象转换为Graphics2D对象，以便使用更多的绘图功能
    Graphics2D g2 = (Graphics2D) g;
    
    // 遍历GameWindow类中的二维数组space
    for (int i = 0; i < GameWindow.VERTICAL_NODES; i ++)
    {
        for (int j = 0; j < GameWindow.HORIZON_NODES; j ++)
        {
            // 如果二维数组中的元素不等于0，则绘制一个实心矩形
            if (GameWindow.space[i][j] != 0)
                g2.fillRect(j * 20, i * 20, 20, 20);
        }
    }
}