设计模式（七）组合模式Composite（结构型）

 比较经典的例子是树形菜单。多级展示，这个菜单可以无限增加节点;例外就是文件遍历等等。
<?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, '">' , $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();
?>