享元模式

享元模式是一种结构型设计模式， 它摒弃了在每个对象中保存所有数据的方式， 通过共享多个对象所共有的相同状态， 让你能在有限的内存容量中载入更多对象

类图

2024072914134428.png

代码

<?php
 
// 享元接口
interface Shape
{
    public function draw(string $color): void;
}
 
// 具体享元类：圆形
class Circle implements Shape
{
    private $radius;
 
    public function __construct(int $radius)
    {
        $this->radius = $radius;
    }
 
    public function draw(string $color): void
    {
        echo "Drawing a Circle with radius {$this->radius} and color {$color}\n";
    }
}
 
 
class ShapeFactory
{
    private $circles = [];
 
    public function getCircle(int $radius): Circle
    {
        if (!isset($this->circles[$radius])) {
            $this->circles[$radius] = new Circle($radius);
        }
        return $this->circles[$radius];
    }
 
    public function getCircleCount(): int
    {
        return count($this->circles);
    }
}
 
 
// 客户端代码
$factory = new ShapeFactory();
 
$colors = ["Red", "Green", "Blue", "Yellow", "Black"];
 
for ($i = 0; $i < 10; $i++) {
    $radius = rand(1, 3);  // 随机半径为 1 到 3 的圆
    $circle = $factory->getCircle($radius);
    $color = $colors[array_rand($colors)];
    $circle->draw($color);
}
 
echo "Total Circle objects created: " . $factory->getCircleCount() . "\n";

不使用享元模式

<?php
 
// 不使用享元模式的具体类：圆形
class CircleWithoutFlyweight
{
    private $radius;
 
    public function __construct(int $radius)
    {
        $this->radius = $radius;
    }
 
    public function draw(string $color): void
    {
        echo "Drawing a Circle with radius {$this->radius} and color {$color}\n";
    }
}
 
// 客户端代码
$colors = ["Red", "Green", "Blue", "Yellow", "Black"];
 
for ($i = 0; $i < 10; $i++) {
    $radius = rand(1, 3);  // 随机半径为 1 到 3 的圆
    $circle = new CircleWithoutFlyweight($radius);
    $color = $colors[array_rand($colors)];
    $circle->draw($color);
}