<?php  
/** 
* 策略模式 
* 定义一系列的算法,把每一个算法封装起来, 并且使它们可相互替换。本模式使得算法可独立于使用它的客户而变化 
* 
*/   
  
  
/** 
* 出行旅游 
* 
*  
*/  
interface TravelStrategy{  
    public function travelAlgorithm();  
}   
  
  
/** 
 * 具体策略类(ConcreteStrategy)1：乘坐飞机 
 */  
class AirPlanelStrategy implements TravelStrategy {  
    public function travelAlgorithm(){  
        echo "travel by AirPlain", "<BR>\r\n";   
    }  
}   
  
  
/** 
 * 具体策略类(ConcreteStrategy)2：乘坐火车 
 */  
class TrainStrategy implements TravelStrategy {  
    public function travelAlgorithm(){  
        echo "travel by Train", "<BR>\r\n";   
    }  
}   
  
/** 
 * 具体策略类(ConcreteStrategy)3：骑自行车 
 */  
class BicycleStrategy implements TravelStrategy {  
    public function travelAlgorithm(){  
        echo "travel by Bicycle", "<BR>\r\n";   
    }  
}   
  
  
  
/** 
 *  
 * 环境类(Context):用一个ConcreteStrategy对象来配置。维护一个对Strategy对象的引用。可定义一个接口来让Strategy访问它的数据。 
 * 算法解决类，以提供客户选择使用何种解决方案： 
 */  
class PersonContext{  
    private $_strategy = null;  
  
    public function __construct(TravelStrategy $travel){  
        $this->_strategy = $travel;  
    }  
    /** 
    * 旅行 
    */  
    public function setTravelStrategy(TravelStrategy $travel){  
        $this->_strategy = $travel;  
    }  
    /** 
    * 旅行 
    */  
    public function travel(){  
        return $this->_strategy ->travelAlgorithm();  
    }  
}   
  
// 乘坐火车旅行  
$person = new PersonContext(new TrainStrategy());  
$person->travel();  
  
// 改骑自行车  
$person->setTravelStrategy(new BicycleStrategy());  
$person->travel();  
  
?>

<?php
/**
 *参考IBM官网：http://www.ibm.com/developerworks/cn/opensource/os-php-designptrns/
 *@author http://www.phpddt.com
 */
//观察者
interface IObserver 
{
	public function notify();
}
//定义可以被观察的对象接口
interface IObservable 
{
	public function addObserver($observer);
}
//实现IObservable接口
class MessageSystem Implements IObservable 
{
	private $_observers = array();
	public function addObserver($observer)
	{
		$this->_observers = $observer;
	}
	public function doNotify()
	{
		foreach($this->_observers as $o)
		{
			$o->notify();
		}
	}
}
//实现IObserver接口
class User Implements IObserver
{
	public function __construct($username)
	{
		echo "我是新用户{$username}<br/>";
	}
	//通知观察者方法
	public function notify()
	{
		echo '欢迎新用户';
	}
}
//使用
$u = new MessageSystem();
$u->addObserver(new User('小明'));
//$u->addObserver(new User('小红'));
//$u->addObserver(new User('小黑'));
$u->doNotify();

class A
{
    protected static $_instance = null;
    protected function __construct()
    {
        //disallow new instance
    }
    protected function __clone(){
        //disallow clone
    }
    public function getInstance()
    {
        if (self::$_instance === null) {
            self::$_instance = new self();
        }
        return self::$_instance;
    }
}

class DbFactory
{
function static factory($db_class_name)
{
        $db_class_name = strtolower($db_class_name);
        if (include_once 'Drivers/' . $db_class_name . '.php') {
     
            $classname = 'Driver_' . $db_class_name;
            return new $db_class_name;
        } else {
            throw new Exception ('对应的数据库类没找到');
        } 
}
}

<?php
//目标角色
interface Target {
	public function simpleMethod1();
	public function simpleMethod2();
}
//源角色
class Adaptee {
	
	public function simpleMethod1(){
		echo 'Adapter simpleMethod1';
	}
}
//类适配器角色
class Adapter implements Target {
	private $adaptee;
	
	
	function __construct(Adaptee $adaptee) {
		$this->adaptee = $adaptee; 
	}
	
	//委派调用Adaptee的sampleMethod1方法
	public function simpleMethod1(){
		echo $this->adaptee->simpleMethod1();
	}
	
	public function simpleMethod2(){
		echo 'Adapter simpleMethod2'; 	
	} 
	
}
//客户端
class Client {
	
	public static function main() {
		$adaptee = new Adaptee();
		$adapter = new Adapter($adaptee);
		$adapter->simpleMethod1();
		$adapter->simpleMethod2(); 
	}
}
Client::main();
?>

//被装饰者基类
interface Component
{
    public function operation();
}
 
//装饰者基类
abstract class Decorator implements Component
{
    protected $component;
 
    public function __construct(Component $component)
    {
        $this->component = $component;
    }
 
    public function operation()
    {
        $this->component->operation();
    }
}
 
//具体装饰者类
class ConcreteComponent implements Component
{
    public function operation()
    {
        echo 'do operation'.PHP_EOL;
    }
}
 
//具体装饰类A
class ConcreteDecoratorA extends Decorator {
    public function __construct(Component $component) {
        parent::__construct($component);
 
    }
 
    public function operation() {
        parent::operation();
        $this->addedOperationA();   //  新增加的操作
    }
 
    public function addedOperationA() {
        echo 'Add Operation A '.PHP_EOL;
    }
}
 
//具体装饰类B
class ConcreteDecoratorB extends Decorator {
    public function __construct(Component $component) {
        parent::__construct($component);
 
    }
 
    public function operation() {
        parent::operation();
        $this->addedOperationB();
    }
 
    public function addedOperationB() {
        echo 'Add Operation B '.PHP_EOL;
    }
}
 
 
class Client {
 
    public static function main() {
        /*
        do operation
        Add Operation A
        */
        $decoratorA = new ConcreteDecoratorA(new ConcreteComponent());
        $decoratorA->operation();
 
 
        /*
        do operation
        Add Operation A 
        Add Operation B  
        */
        $decoratorB = new ConcreteDecoratorB($decoratorA);
        $decoratorB->operation();
    }
 
}
 
Client::main();
转自: http://www.phpddt.com/php/design-decoration.html