享元模式（Flyweight）

模式架构简单代码实现示例：

<?php
abstract class Resources{
    public $resource=null;
    abstract public function operate();
}
class unShareFlyWeight extends Resources{
    public function __construct($resource_str) {
        $this->resource = $resource_str;
    }
    public function operate(){
        echo $this->resource."<br>";
    }
}
class shareFlyWeight extends Resources{
    private $resources = array();
    public function get_resource($resource_str){
        if(isset($this->resources[$resource_str])) {
            return $this->resources[$resource_str];
        }else {
            return $this->resources[$resource_str] = $resource_str;
        }
    }
    public function operate(){
        foreach ($this->resources as $key => $resources) {
            echo $key.":".$resources."<br>";
        }
    }
}

// client
$flyweight = new shareFlyWeight();
$flyweight->get_resource('a');
$flyweight->operate();
$flyweight->get_resource('b');
$flyweight->operate();
$flyweight->get_resource('c');
$flyweight->operate();
// 不共享的对象，单独调用
$uflyweight = new unShareFlyWeight('A');
$uflyweight->operate();
$uflyweight = new unShareFlyWeight('B');
$uflyweight->operate();