PHP的观察者设计模式实现相对简单，可是PHP5+版本号中已经有标准库类库支持，我们仅仅需简单继承并实现就能够了。

观察者：实现标准接口类库SplSubject。

一个注冊方法：attach。一个取消注冊方法：detach。一个通知方法：nofity。

<?php

class TSPLSubject implements SplSubject{

	 private $observers, $value;

	 public function __construct(){

		$this->observers =array();

	 }

	 public function attach(SplObserver $observer){

		$this->observers[] = $observer;

	 }

	 public function detach(SplObserver $observer){

		if($idx = array_search($observer, $this->observers,true)) {

			unset($this->observers[$idx]);

		}

	 }

    /**

	 *

	 * Notify observers one by one (main entry)

	 *

	 * @param none

	 * @return none

	 */

	 public function notify(){

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

			$observer->update($this);

		}

	 }

	 public function setValue($value){

		$this->value = $value;

		//$this->notify();

	 }

	 public function getValue(){

		 return $this->value;

	 }

}

被观察者：实现标准接口类库SplObserver。一个update方法。

<?php

class TSPLObserver implements SplObserver{

	 public function update(SplSubject $subject){

		 echo 'The new state of subject ' , nl2br("\r\n");

//		 echo 'The new state of subject '.$subject->getValue();

	 }

}

<?

php

class TSPLObserver1 implements SplObserver{

	 public function update(SplSubject $subject){

		 echo 'The new state of subject one ' , nl2br("\r\n");

//		 echo 'The new state of subject '.$subject->getValue();

	 }

}

測试调用（同文件夹下）：

<?

php

function __autoload($classname) {

  require_once ($classname . ".php");

}

$subject = new TSPLSubject();

$subject->attach(new TSPLObserver());

$observer1 = new TSPLObserver1();

$subject->attach($observer1);

//$subject->attach(new TSPLObserver2());

//$subject->detach($observer1);

$subject->notify();

exit();

输出：

>php basic.php

The new state of subject <br />

The new state of subject one <br />