设计模式(11)flyweight模式

/**
 * 抽象享元角色
 */
abstract class Flyweight {
  
 /**
  * 示意性方法
  * @param string $state 外部状态
  */
 abstract public function operation($state);
}
  
/**
 * 具体享元角色
 */
class ConcreteFlyweight extends Flyweight {
  
 private $_intrinsicState = null;
  
 /**
  * 构造方法
  * @param string $state 内部状态
  */
 public function __construct($state) {
  $this->_intrinsicState = $state;
 }
  
 public function operation($state) {
  echo 'ConcreteFlyweight operation, Intrinsic State = ' . $this->_intrinsicState
  . ' Extrinsic State = ' . $state . '<br />';
 }
  
}
  
/**
 * 不共享的具体享元，客户端直接调用
 */
class UnsharedConcreteFlyweight extends Flyweight {
  
 private $_intrinsicState = null;
  
 /**
  * 构造方法
  * @param string $state 内部状态
  */
 public function __construct($state) {
  $this->_intrinsicState = $state;
 }
  
 public function operation($state) {
  echo 'UnsharedConcreteFlyweight operation, Intrinsic State = ' . $this->_intrinsicState
  . ' Extrinsic State = ' . $state . '<br />';
 }
  
}
  
/**
 * 享元工厂角色
 */
class FlyweightFactory {
  
 private $_flyweights;
  
 public function __construct() {
  $this->_flyweights = array();
 }
  
 public function getFlyweigth($state) {
  if (isset($this->_flyweights[$state])) {
   return $this->_flyweights[$state];
  } else {
   return $this->_flyweights[$state] = new ConcreteFlyweight($state);
  }
 }
  
}
  
$flyweightFactory = new FlyweightFactory();
$flyweight = $flyweightFactory->getFlyweigth('state A');
$flyweight->operation('other state A');

$flyweight = $flyweightFactory->getFlyweigth('state B');
$flyweight->operation('other state B');

/* 不共享的对象，单独调用 */
$uflyweight = new UnsharedConcreteFlyweight('state A');
$uflyweight->operation('other state A');