PHP设计模式（七）组合模式Composite实例详解【结构型】

<?php 
/**
 * 组合模式 
 * 
 * @author guisu
 * @version 1.0
 * 组合模式:树形菜单
 * 
 * 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 
 */ 
/**
 * 抽象构件角色（component）
 *
 */
abstract class MenuComponent
{
 public function add($component){}
 public function remove($component){}
 public function getName(){}
 public function getUrl(){}
 public function displayOperation(){}
}
/**
 * 树枝构件角色（Composite）
 *
 */
class MenuComposite extends MenuComponent
{
 private $_items = array();
 private $_name = null;
 private $_align = '';
 public function __construct($name) {
 $this->_name = $name;
 }
 public function add($component) {
 $this->_items[$component->getName()] = $component;
 }
 public function remove($component) {
 $key = array_search($component,$this->_items);
 if($key !== false) unset($this->_items[$key]);
 }
 public function getItems() {
 return $this->_items;
 }
 public function displayOperation() {
 static $align = '|';
 if($this->getItems()) {
  //substr($align, strpos($align,));
  $align .= ' _ _ ';
 }else{
  $align .='';
 }
 echo $this->_name, " <br/>";
 foreach($this->_items as $name=> $item) {
  echo $align;
  $item->displayOperation();
 }
 }
 public function getName(){
 return $this->_name;
 }
}
/**
 *树叶构件角色(Leaf)
 *
 */
class ItemLeaf extends MenuComponent
{
 private $_name = null;
 private $_url = null;
 //public $_align = '----';
 public function __construct($name,$url)
 {
 $this->_name = $name;
 $this->_url = $url;
 }
 public function displayOperation()
 {
 echo '<a href="', $this->_url, '" rel="external nofollow" >' , $this->_name, '</a><br/>';
 }
 public function getName(){
 return $this->_name;
 }
}
class Client
{
 public static function displayMenu()
 {
 $subMenu1 = new MenuComposite("submenu1");
 $subMenu2 = new MenuComposite("submenu2");
 $subMenu3 = new MenuComposite("submenu3");
 $subMenu4 = new MenuComposite("submenu4");
 $subMenu5 = new MenuComposite("submenu5");
 /*
 $item1 = new ItemLeaf("sohu","www.163.com");
 $item2 = new ItemLeaf("sina","www.sina.com");
 $subMenu4 = new MenuComposite("submenu4");
 $subMenu1->add($subMenu4);
 $subMenu4->add($item1);
 $subMenu4->add($item2);
 */
 $item3 = new ItemLeaf("baidu","www.baidu.com");
 $item4 = new ItemLeaf("google","www.google.com");
 $subMenu2->add($item3);
 $subMenu2->add($item4);
 $allMenu = new MenuComposite("AllMenu");
 $allMenu->add($subMenu1);
 $allMenu->add($subMenu2);
 $allMenu->add($subMenu3);
 $subMenu3->add($subMenu4);
 $subMenu4->add($subMenu5);
 $allMenu->displayOperation();
 }
}
// 创建menu
Client::displayMenu();
?>