具体如下：

_name = $name;  }  public function add($component)  {    $this->_items[] = $component;  }  public function remove($component)  {    $key = array_search($component, $this->_items);    if ($key !== false) unset($this->_items[$key]);  }  public function display()  {    echo "-- " . $this->_name . " --------- \r\n ";    foreach ($this->_items as $item) {      $item->display();    }  }}class Item extends MenuComponent{  private $_name = null;  private $_url = null;  public function __construct($name, $url)  {    $this->_name = $name;    $this->_url = $url;  }  public function display()  {    echo $this->_name . "#" . $this->_url . " \r\n ";  }}class Client{  private $_menu = null;  public function __construct($menu)  {    $this->_menu = $menu;  }  public function setMenu($menu)  {    $this->_menu = $menu;  }  public function displayMenu()  {    $this->_menu->display();  }}// 实例一下// 人$item3 = new Item("baidu", "www.baidu.com");$item4 = new Item("google", "www.google.com");$item1 = new Item("163", "www.163.com");$item2 = new Item("sina", "www.sina.com");// 班级$subMenu1 = new Menu("sub menu1");$subMenu1->add($item1);$subMenu1->add($item2);$subMenu2 = new Menu("sub menu2");$subMenu2->add($item3);$subMenu2->add($item4);$subMenu3 = new Menu("sub menu3");$subMenu3->add($item3);$subMenu3->add($item4);// 所有班级$allMenu = new Menu("All Menu");$allMenu->add($subMenu1);$allMenu->add($subMenu2);$allMenu->add($subMenu3);// 打印所有班级$objClient = new Client($allMenu);$objClient->displayMenu();// 打印第2 班级$objClient->setMenu($subMenu2);$objClient->displayMenu();?>

运行结果：

-- All Menu --------- -- sub menu1 --------- 163#www.163.comsina#www.sina.com -- sub menu2 --------- baidu#www.baidu.com google#www.google.com -- sub menu3 --------- baidu#www.baidu.com google#www.google.com -- sub menu2 --------- baidu#www.baidu.com google#www.google.com