运用共享技术有效的支持大量细粒度的对象
    享元，就是分享元素的意思，跟注册当时的意思差不多，注册到一个容器中，这个是保存在享元工厂中，有就返回，没有就实例化然后返回，
    一般池技术就是享元模式的重要实现方式，string常量池，数据库连接池，缓冲池等，

    有对象的外部状态跟内部状态，内部状态时确定这个类的，共享，不能修改，外部状态就是参数，不共享能修改，
    一个类实例化之后，放在享元工厂中，通过内部状态判断，
    image.png

    1. <?php
    3. /**
    4.  * 接口类
    5.  */
    6. interface  Flyweight
    7. {
    8.     public function operation($extrinsicState): void;
    9. }
    11. /**
    12.  * 接口实现类共享
    13.  */
    14. class ConcreteFlyweight implements Flyweight
    15. {
    16.     //内部状态，共享
    17.     private $template;
    19.     function __construct($temp)
    20.     {
    21.         //实例化确定
    22.         $this->template = $temp;
    23.     }
    25.     //外部状态不共享
    26.     public function operation($extrinsicState): void
    27.     {
    28.         echo $this->template . '方棋子方位：' . $extrinsicState . PHP_EOL;
    29.     }
    31. }
    33. /**
    34.  * 接口实现类不共享
    35.  */
    36. class UnsharedConcreteFlyweight implements Flyweight
    37. {
    38.     //内部状态，共享
    39.     private $template;
    41.     function __construct($temp)
    42.     {
    43.         //实例化确定
    44.         $this->template = $temp;
    45.     }
    47.     //外部状态不共享
    48.     public function operation($extrinsicState): void
    49.     {
    50.         echo $this->template . '方棋子方位：' . $extrinsicState . PHP_EOL;
    51.     }
    53. }
    55. /**
    56.  * 享元工厂
    57.  */
    58. class FlyweightFactory
    59. {
    60.     private $flyweights;
    62.     public function getFlyweight($key)
    63.     {
    64.         if (!array_key_exists($key, $this->flyweights)) {
    65.             echo '创建实例：' . $key . PHP_EOL;
    66.             $this->flyweights[$key] = new ConcreteFlyweight($key);
    67.         }
    68.         echo '拿到实例：' . $key . PHP_EOL;
    69.         return $this->flyweights[$key];
    70.     }
    72.     public function count()
    73.     {
    74.         echo '实例数量：' . count($this->flyweights) . PHP_EOL;
    75.     }
    76. }
    78. //实例化享元工厂
    79. $factory = new FlyweightFactory();
    81. //获取一个实例
    82. $flA = $factory->getFlyweight('黑');
    83. $flA->operation('七右之十四');
    84. $factory->count();
    85. $flA = $factory->getFlyweight('黑');
    86. $flA->operation('七右之六');
    87. $factory->count();
    89. //获取一个实例
    90. $flA = $factory->getFlyweight('白');
    91. $flA->operation('六右之三');
    92. $factory->count();
    93. $flA = $factory->getFlyweight('白');
    94. $flA->operation('六右之六');
    95. $factory->count();
    97. //非共享
    98. $Unshared = new UnsharedConcreteFlyweight('彩');
    99. $Unshared->operation('六右之六');