php设计模式 Bridge (桥接模式)

<?php 
/** 
* 桥接模式 
* 
* 将抽象部份与它实现部分分离,使用它们都可以有独立的变化 
*/ 
abstract class Implementor 
{ 
abstract public function operation(); 
} 
class ConcreteImplementorA extends Implementor 
{ 
public function operation() 
{ 
echo "ConcreteImplementorA Operation<br/>"; 
} 
} 
class ConcreteImplementorB extends Implementor 
{ 
public function operation() 
{ 
echo "ConcreteImplementorB Operation<br/>"; 
} 
} 
class Abstraction 
{ 
protected $_implementor = null; 
public function setImplementor($implementor) 
{ 
$this->_implementor = $implementor; 
} 
public function operation() 
{ 
$this->_implementor->operation(); 
} 
} 
class RefinedAbstraction extends Abstraction 
{ 
} 
class ExampleAbstraction extends Abstraction 
{ 
} 
// 
$objRAbstraction = new RefinedAbstraction(); 
$objRAbstraction->setImplementor(new ConcreteImplementorB()); 
$objRAbstraction->operation(); 
$objRAbstraction->setImplementor(new ConcreteImplementorA()); 
$objRAbstraction->operation(); 
$objEAbstraction = new ExampleAbstraction(); 
$objEAbstraction->setImplementor(new ConcreteImplementorB()); 
$objEAbstraction->operation();