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php design pattern observer pattern, design pattern observer
Home Backend Development PHP Tutorial PHP design patterns observer pattern, design pattern observer_PHP tutorial

PHP design patterns observer pattern, design pattern observer_PHP tutorial

Jul 12, 2016 am 08:58 AM
Design Patterns

php design pattern observer pattern, design pattern observer

The core of the observer pattern is to separate the client element (observer) from a central class (subject) . Observers need to be notified when the subject knows that an event has occurred. At the same time, we do not want to hardcode the relationship between the subject and the observer. To achieve this, we can allow observers to register on the subject.

The observer pattern implements a low-coupling, non-intrusive notification and update mechanism.

Scenario: When an event occurs, a series of update operations must be performed.

<span>EventGenerator</span>.php
<?<span>php
namespace Baobab;
</span><span>/*</span><span>*
 * Class EventGenerator 基類,事件發(fā)生者
 </span><span>*/</span>
<span>abstract</span> <span>class</span><span> EventGenerator{

    </span><span>//</span><span>觀察者對于事件發(fā)生者是不可見的,事件發(fā)生者不關(guān)心有哪些觀察者關(guān)注了事件</span>
    <span>private</span> <span>$observers</span> = <span>array</span><span>();

    </span><span>/*</span><span>*
     * 添加觀察者
     </span><span>*/</span>
    <span>function</span> addObserver(Observer <span>$observer</span><span>){
        </span><span>$this</span>->observers[] = <span>$observer</span><span>;
    }

    </span><span>/*</span><span>*
     *逐個通知觀察者進(jìn)行更新的操作
     </span><span>*/</span>
    <span>function</span><span> notify(){
        </span><span>foreach</span>(<span>$this</span>->observers <span>as</span> <span>$observer</span><span>){
            </span><span>$observer</span>-><span>update();
        }
    }
}</span>
<span>Observer</span>.php
<?<span>php
namespace Baobab;
</span><span>/*</span><span>*
 * Class Observer 觀察者,觀察的對象是事件發(fā)生者
 * @package Baobab
 </span><span>*/</span>
<span>interface</span><span> Observer{
    </span><span>/*</span><span>*
     * @param null $event_info  事件的信息
     * 表示事件發(fā)生后進(jìn)行更新的操作
     </span><span>*/</span>
    <span>function</span> update(<span>$event_info</span> = <span>null</span><span>);
}</span>

index.php

<span>class</span> Event <span>extends</span><span> \Baobab\EventGenerator{
    </span><span>/*</span><span>*
     *觸發(fā)一個新的事件
     </span><span>*/</span>
    <span>function</span><span> trigger(){
        </span><span>echo</span> 'Event發(fā)生'<span>;
        </span><span>$this</span>-><span>notify();
    }
}

</span><span>/*</span><span>*
 * 觀察者1
 </span><span>*/</span>
<span>class</span> Observer1 <span>implements</span><span> \Baobab\Observer{
    </span><span>function</span> Update(<span>$event_info</span> = <span>null</span><span>){
        </span><span>echo</span> '更新操作代碼1'<span>;
    }
}<br />
<span>/*<span>* <br /> * 觀察者2 <br /><span> */</span></span></span>
</span><span>class</span> Observer2 <span>implements</span><span> \Baobab\Observer{
    </span><span>function</span> Update(<span>$event_info</span> = <span>null</span><span>){
        </span><span>echo</span> '更新操作代碼2'<span>;
    }
}

</span><span>$event</span> = <span>new</span><span> Event();
</span><span>$event</span>->addObserver(<span>new</span><span> Observer1());
</span><span>$event</span>->addObserver(<span>new</span><span> Observer2());
</span><span>$event</span>->trigger();

www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/1105142.htmlTechArticlephp design pattern observer pattern, design pattern observer The core of the observer pattern is to combine customer elements (observers) Separate from a central class (subject). When the subject knows the event...
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