PHP观察者模式原理与简单实现方法示例

interface SplSubject
{
  function attach(SplObserver $observer);
  function detach(SplObserver $observer);
  function notify();
}
interface SqlObserver
{
  function update(SplSubject $subject);
}

class Subject implements SplSubject
{
  private $observers;
  public function attach(SplObserver $observer)
  {
    if (!in_array($observer, $this->observers)) {
      $this->observers[] = $observer;
    }
  }
  public function detach(SplObserver $observer)
  {
    if (false != ($index = array_search($observer, $this->observers))) {
      unset($this->observers[$index]);
    }
  }
  public function post()
  {
    //post相关code
    $this->notify();
  }
  private function notify()
  {
    foreach ($this->observers as $observer) {
      $observer->update($this);
    }
  }
  public function setCount($count)
  {
    echo "数据量加" . $count;
  }
  public function setIntegral($integral)
  {
     echo "积分量加" . $integral;
  }
}
class Observer1 implements SplObserver
{
  public function update($subject)
  {
    $subject-> setCount(1);
  }
}
class Observer2 implements SplObserver
{
  public function update($subject)
  {
    $subject-> setIntegral(10);
  }
}
class Client
{
  public function test()
  {
    $subject = new Subject();
    $subject->attach(new Observer1());
    $subject->attach(new Observer2());
    $subject->post();//输出：数据量加1 积分量加10
  }
}