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
