《Head First设计模式》读书笔记（二）

对于观察者模式,PHP通过标准PHP库(SPL)提供了内建的支持，下面用SPL对昨天的观察者模式示例进行修改。

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代码

<?php

    class WeatherData implements SplSubject

    {

        private $observers = null;

        private $temperature = 0;

        private $humidity = 0;

        private $pressure = 0;

        public __construct()

        {

            $this->observers = new SplObjectStorage();

        }

        public function getTemperature()

        {

            return $this->temperature;

        }

        public function setTemperature($temp)

        {

            $this->temperature = $temp;

        }    

        public function getHumidity()

        {

            return $this->humidity;

        }

        public function setHumidity($humidity)

        {

            $this->humidity = $humidity;

        }

        public function getPressure()    

        {

            return $this->pressure;

        }

        public function setPressure($pressure)

        {    

            $this->pressure = $pressure;

        }

        public function setMeasurements($temperature, $humidity, $pressure) 

        {

            $this->setTemperature($temperature);

            $this->setHumidity($humidity);

            $this->setPressure($pressure);

            $this->measureChanged();            

        }

        public function measureChanged()

        {

            $this->notify();

        }

        public function attach(SplObserver $observer)

        {

            $this->observers->attach($observer);

        }

        public function detach(SplObserver $observer)

        {

            $this->observers->detach($observer);

        }

        public function notify()

        {

            foreach ($this->observers as $observer) {

                $observer->update($this);

            }

        }

        public function getObservers() 

        {

            return $this->observers;

        }

    }

    abstract class BaseDisplay implements SplObserver

    {

        private $weatherData = null; 

        public function __construct(WeatherData $weatherData = null)

        {

            $this->weatherData = $weatherData;

            if ($weatherData != null) {

                $this->weatherData->attach($this);

            }

        }

        public function update(SplSubject $subject)

        {

            if ($subject === $this->weatherData) {

                $this->realUpdate($subject);

            }

        }

        abstract function realUpdate(WeatherData $weatherData);

    }

    class CurrentConditionDisplay extends BaseDisplay

    {

        private $temperature = 0;

        private $humidity = 0;

        private $pressure = 0;

        function realUpdate(WeatherData $weatherData)    

        {

            $this->temperature = $weatherData->getTemperature();

            $this->humidity = $weatherData->getHumidity();

            $this->pressure = $weatherData->getPressure();

            print("temp: " . $this->temperature . ", humi: " . $this->humidity . ", pressure: " . $this->pressure . "\n");

        }

    }

    class GeneralDisplay extends BaseDisplay

    {

        function realUpdate(WeatherData $weatherData)    

        {

            print("GeneralDisplay\n");

        }

    }

    $weatherData = new WeatherData();

    $display = new CurrentConditionDisplay($weatherData);

    $display2 = new GeneralDisplay($weatherData);

    $weatherData->setMeasurements(20,30,40);

    $weatherData->detach($display2);

    print("after...\n");

    $weatherData->setMeasurements(33,44,55);

?>

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本文转自Phinecos(洞庭散人)博客园博客，原文链接：http://www.cnblogs.com/phinecos/archive/2010/07/07/1772656.html，如需转载请自行联系原作者