php设计模式 Composite (组合模式)

<?php 
 /** 
 * 组合模式 
 * 
 * 将对象组合成树形结构以表示"部分-整体"的层次结构,使得客户对单个对象和复合对象的使用具有一致性 
 */ 
 abstract class MenuComponent 
 { 
 public function add($component){} 
public function remove($component){} 
public function getName(){} 
public function getUrl(){} 
public function display(){} 
} 
class Menu extends MenuComponent 
{ 
private $_items = array(); 
private $_name = null; 
public function __construct($name) 
{ 
$this->_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 "-- ".$this->_name." ---------<br/>"; 
foreach($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."<br/>"; 
} 
} 
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 
// 创建menu 
$subMenu1 = new Menu("sub menu1"); 
$subMenu2 = new Menu("sub menu2"); 
$subMenu3 = new Menu("sub menu3"); 
$item1 = new Item("163","www.163.com"); 
$item2 = new Item("sina","www.sina.com"); 
$subMenu1->add($item1); 
$subMenu1->add($item2); 
$item3 = new Item("baidu","www.baidu.com"); 
$item4 = new Item("google","www.google.com"); 
$subMenu2->add($item3); 
$subMenu2->add($item4); 
$allMenu = new Menu("All Menu"); 
$allMenu->add($subMenu1); 
$allMenu->add($subMenu2); 
$allMenu->add($subMenu3); 
$objClient = new Client($allMenu); 
$objClient->displayMenu(); 
$objClient->setMenu($subMenu2); 
$objClient->displayMenu();