php设计模式 Mediator (中介者模式)

<?php 
/** 
* 中介者模式 
* 
* 用一个中介对象来封装一系列的对象交互,使各对象不需要显式地相互引用从而使其耦合松散,而且可以独立地改变它们之间的交互 
*/ 
abstract class Mediator 
{ 
abstract public function send($message,$colleague); 
} 
abstract class Colleague 
{ 
private $_mediator = null; 
public function Colleague($mediator) 
{ 
$this->_mediator = $mediator; 
} 
public function send($message) 
{ 
$this->_mediator->send($message,$this); 
} 
abstract public function notify($message); 
} 
class ConcreteMediator extends Mediator 
{ 
private $_colleague1 = null; 
private $_colleague2 = null; 
public function send($message,$colleague) 
{ 
if($colleague == $this->_colleague1) 
{ 
$this->_colleague1->notify($message); 
} else { 
$this->_colleague2->notify($message); 
} 
} 
public function set($colleague1,$colleague2) 
{ 
$this->_colleague1 = $colleague1; 
$this->_colleague2 = $colleague2; 
} 
} 
class Colleague1 extends Colleague 
{ 
public function notify($message) 
{ 
echo "Colleague1 Message is :".$message."<br/>"; 
} 
} 
class Colleague2 extends Colleague 
{ 
public function notify($message) 
{ 
echo "Colleague2 Message is :".$message."<br/>"; 
} 
} 
// 
$objMediator = new ConcreteMediator(); 
$objC1 = new Colleague1($objMediator); 
$objC2 = new Colleague2($objMediator); 
$objMediator->set($objC1,$objC2); 
$objC1->send("to c2 from c1"); 
$objC2->send("to c1 from c2");