public void onKeyEvent(KeyEvent e) {
		if (player == null) return;

		switch (e.getKeyCode()) {

		// 上
		case KeyEvent.VK_UP:
			player.moveUp();
			break;

		case KeyEvent.VK_DOWN:
			player.moveDown();
			break;

		case KeyEvent.VK_LEFT:
			player.moveLeft();
			break;

		case KeyEvent.VK_RIGHT:
			player.moveRight();
			break;

		case KeyEvent.VK_SPACE:
			Bullet bullet = player.shoot();
			bullets.add(bullet);
			break;
		}
	}