[设计模式]head first 设计模式之PHP实现 第二章 观察者模式

 <?php abstract class Subject {abstract public function addObj(User $u); //增加用户 abstract public function removeObj(User $u); //移除用户 abstract public function notify(); //通知用户}interface DisplayElement {public function display();}interface User {//当这三个值改变时，Subject 会把这些状态值当作方法的参数，传递给观察者public function update($name,$url,$comment); }class Office extends Subject {private $users = array();private $name;private $url;private $comment;public function addObj(User $u){$this->users[] = $u; }public function removeObj(User $u){//判断$u是否存在于$users数组中$key = array_search($u,$this->users);if(false !== $key){unset($this->users[$key]);}}//更新每个观察者的显示数据public function notify(){foreach($this->users as $key=>$val){$val->update($this->name,$this->url,$this->comment);}}//数据更新public function dataChange(){$this->notify();}//设置数据public function setData($name,$url,$comment){$this->name = $name;$this->url = $url;$this->comment = $comment;$this->dataChange();}}/* * User1为一个观察者 */class User1 implements User,DisplayElement {public $offdata;private $name;private $url;private $comment;public function __construct(Office $offdata){$this->offdata = $offdata;$this->offdata->addObj($this);}public function update($name,$url,$comment){$this->name = $name;$this->url = $url;$this->comment = $comment;$this->display();}public function display(){echo 'name = '.$this->name.'<br />';echo 'url = '.$this->url.'<br />';echo 'comment = '.$this->comment.'<br />';}}/* * User2为一个观察者 */class User2 implements User,DisplayElement {public $offdata;private $name;private $url;private $comment;public function __construct(Office $offdata){$this->offdata = $offdata;$this->offdata->addObj($this);}public function update($name,$url,$comment){$this->name = $name;$this->url = $url;$this->display();}public function display(){echo 'name = '.$this->name.'<br />';echo 'url = '.$this->url.'<br />';}}$a=new Office();//先实例一个对象。一个神诞生了。他能给我们新闻$u1 = new User1($a);//把WebBrowser对象实例化并且注册给这个主题；$u2 = new User2($a);$a->setData('gg','http://g.cn','google');echo '-------------------<br/>';?>