PHP设计模式之组合模式定义与应用示例

?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 "-- " . $this->_name . " --------- \r\n ";
    foreach ($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();
?>