<?php
interface Strategy { // 抽象策略角色，以接口實(shí)現(xiàn)
  public function algorithmInterface(); // 算法接口
}

class ConcreteStrategyA implements Strategy { // 具體策略角色A 
  public function algorithmInterface() {}
}

class ConcreteStrategyB implements Strategy { // 具體策略角色B 
  public function algorithmInterface() {}
}

class ConcreteStrategyC implements Strategy { // 具體策略角色C
  public function algorithmInterface() {}
}

class Context { // 環(huán)境角色
  private $_strategy;
  public function __construct(Strategy $strategy) {
    $this->_strategy = $strategy;
  } 
  public function contextInterface() {
    $this->_strategy->algorithmInterface();
  }
}

// client
$strategyA = new ConcreteStrategyA();
$context = new Context($strategyA);
$context->contextInterface();

$strategyB = new ConcreteStrategyB();
$context = new Context($strategyB);
$context->contextInterface();

$strategyC = new ConcreteStrategyC();
$context = new Context($strategyC);
$context->contextInterface();

<?php 
/** 
* 策略模式(Strategy.php) 
* 
* 定義一系列算法,把它們一個(gè)個(gè)封裝起來,并且使它們可相互替換,使用得算法的變化可獨(dú)立于使用它的客戶 
* 
*/ 

// ---以下是一系列算法的封閉---- 
interface CacheTable 
{ 
public function get($key); 
public function set($key,$value); 
public function del($key); 
} 

// 不使用緩存 
class NoCache implements CacheTable 
{ 
public function __construct(){ 
echo "Use NoCache<br/>"; 
} 

public function get($key) 
{ 
return false; 
} 

public function set($key,$value) 
{ 
return true; 
} 

public function del($key) 
{ 
return false; 
} 
} 

// 文件緩存 
class FileCache implements CacheTable 
{ 
public function __construct() 
{ 
echo "Use FileCache<br/>"; 
// 文件緩存構(gòu)造函數(shù) 
} 

public function get($key) 
{ 
// 文件緩存的get方法實(shí)現(xiàn) 
} 

public function set($key,$value) 
{ 
// 文件緩存的set方法實(shí)現(xiàn) 
} 

public function del($key) 
{ 
// 文件緩存的del方法實(shí)現(xiàn) 
} 
} 

// TTServer 
class TTCache implements CacheTable 
{ 
public function __construct() 
{ 
echo "Use TTCache<br/>"; 
// TTServer緩存構(gòu)造函數(shù) 
} 

public function get($key) 
{ 
// TTServer緩存的get方法實(shí)現(xiàn) 
} 

public function set($key,$value) 
{ 
// TTServer緩存的set方法實(shí)現(xiàn) 
} 

public function del($key) 
{ 
// TTServer緩存的del方法實(shí)現(xiàn) 
} 
} 

// -- 以下是使用不用緩存的策略 ------ 
class Model 
{ 
private $_cache; 
public function __construct() 
{ 
$this->_cache = new NoCache(); 
} 

public function setCache($cache) 
{ 
$this->_cache = $cache; 
} 
} 

class UserModel extends Model 
{ 
} 

class PorductModel extends Model 
{ 
public function __construct() 
{ 
$this->_cache = new TTCache(); 
} 
} 

// -- 實(shí)例一下 --- 
$mdlUser = new UserModel(); 
$mdlProduct = new PorductModel(); 
$mdlProduct->setCache(new FileCache()); // 改變緩存策略 
?>