在之前的文章《聊聊PHP中的代理模式(正向代理與反向代理)》中我們介紹了PHP中的代理模式,以下這篇文章帶大家了解一下PHP設計模式中的享元模式。
享元模式,「享元」這兩個字在中文裡其實並沒有什麼特殊的意思,所以我們要把它拆分來看。 「享」就是共享,「元」就是元素,這樣一來似乎就很容易理解了,共享某些元素嘛。
GoF定義:運用共享技術有效支援大量細粒度的物件
GoF類別圖
#程式碼實作
interface Flyweight { public function operation($extrinsicState) : void; } class ConcreteFlyweight implements Flyweight { private $intrinsicState = 101; function operation($extrinsicState) : void { echo '共享享元对象' . ($extrinsicState + $this->intrinsicState) . PHP_EOL; } } class UnsharedConcreteFlyweight implements Flyweight { private $allState = 1000; public function operation($extrinsicState) : void { echo '非共享享元对象:' . ($extrinsicState + $this->allState) . PHP_EOL; } }
定義共用介面以及它的實現,注意這裡有兩個實現,ConcreteFlyweigh進行狀態的共享,UnsharedConcreteFlyweight不共享或者說他的狀態不需要去共享
class FlyweightFactory { private $flyweights = []; public function getFlyweight($key) : Flyweight { if (!array_key_exists($key, $this->flyweights)) { $this->flyweights[$key] = new ConcreteFlyweight(); } return $this->flyweights[$key]; } }
保存那些需要共享的對象,做為一個工廠來創建需要的共享對象,保證相同的鍵值下只會有唯一的對象,節省相同對象創建的開銷
$factory = new FlyweightFactory(); $extrinsicState = 100; $flA = $factory->getFlyweight('a'); $flA->operation(--$extrinsicState); $flB = $factory->getFlyweight('b'); $flB->operation(--$extrinsicState); $flC = $factory->getFlyweight('c'); $flC->operation(--$extrinsicState); $flD = new UnsharedConcreteFlyweight(); $flD->operation(--$extrinsicState);
客戶端的調用,讓外部狀態$extrinsicState能夠在各個對象之間共享
還是說到科技以換殼為本這件事上。畢竟,大家都還是喜歡各種顏色的手機來展現自己的個性。之前說過,如果每種顏色我們都要做一條生產線的話那豈不是一項巨大的投入。還好,每個型號我們的工廠(享元工廠)只生產最基本的背景殼(物件),然後透過專門的印刷線(狀態變化)來進行上色不就好啦!嗯,下一款Iphone早晚也會模仿我們的,看來我們得先把各種金、各種土豪色集齊才行,說不定還能召喚神龍呢! !
完整程式碼:https://github.com/zhangyue0503/designpatterns-php/blob/master/13.flyweights/source/flyweights.php
果然不出意外的我們還是來發短信,這回的短信依然使用的阿里雲和極光短信來進行發送,不過這次我們使用享元模式來實現,這裡的享元工廠我們保存了兩種不同類型的物件哦,透過內外狀態來讓它們千變萬化吧!
簡訊發送類別圖
#完整原始碼:https://github.com/zhangyue0503/designpatterns-php /blob/master/13.flyweights/source/flyweights-message.php
template = $template; } public function send(User $user) { echo '使用阿里云短信向' . $user->GetName() . '发送:'; echo $this->template->GetTemplate(), PHP_EOL; } } class JiGuangMessage implements Message { private $template; public function __construct($template) { $this->template = $template; } public function send(User $user) { echo '使用极光短信向' . $user->GetName() . '发送:'; echo $this->template->GetTemplate(), PHP_EOL; } } class MessageFactory { private $messages = []; public function GetMessage(Template $template, $type = 'ali') { $key = md5($template->GetTemplate() . $type); if (!key_exists($key, $this->messages)) { if ($type == 'ali') { $this->messages[$key] = new AliYunMessage($template); } else { $this->messages[$key] = new JiGuangMessage($template); } } return $this->messages[$key]; } public function GetMessageCount() { echo count($this->messages); } } class User { public $name; public function GetName() { return $this->name; } } class Template { public $template; public function GetTemplate() { return $this->template; } } // 内部状态 $t1 = new Template(); $t1->template = '模板1,不错哟!'; $t2 = new Template(); $t2->template = '模板2,还好啦!'; // 外部状态 $u1 = new User(); $u1->name = '张三'; $u2 = new User(); $u2->name = '李四'; $u3 = new User(); $u3->name = '王五'; $u4 = new User(); $u4->name = '赵六'; $u5 = new User(); $u5->name = '田七'; // 享元工厂 $factory = new MessageFactory(); // 阿里云发送 $m1 = $factory->GetMessage($t1); $m1->send($u1); $m2 = $factory->GetMessage($t1); $m2->send($u2); echo $factory->GetMessageCount(), PHP_EOL; // 1 $m3 = $factory->GetMessage($t2); $m3->send($u2); $m4 = $factory->GetMessage($t2); $m4->send($u3); echo $factory->GetMessageCount(), PHP_EOL; // 2 $m5 = $factory->GetMessage($t1); $m5->send($u4); $m6 = $factory->GetMessage($t2); $m6->send($u5); echo $factory->GetMessageCount(), PHP_EOL; // 2 // 加入极光 $m1 = $factory->GetMessage($t1, 'jg'); $m1->send($u1); $m2 = $factory->GetMessage($t1); $m2->send($u2); echo $factory->GetMessageCount(), PHP_EOL; // 3 $m3 = $factory->GetMessage($t2); $m3->send($u2); $m4 = $factory->GetMessage($t2, 'jg'); $m4->send($u3); echo $factory->GetMessageCount(), PHP_EOL; // 4 $m5 = $factory->GetMessage($t1, 'jg'); $m5->send($u4); $m6 = $factory->GetMessage($t2, 'jg'); $m6->send($u5); echo $factory->GetMessageCount(), PHP_EOL; // 4
說明
原文位址:https://juejin.cn /post/6844903965814259726
作者:硬核心專案經理
推薦學習:《PHP影片教學》
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