Review PHP设计模式之——观测模式

观测模式：

  1 <?php
  2 class car implements SplSubject{
  3     private $carName;    //车的类型
  4     private $carState=0; //车的状态，0为关闭，1这启动车子
  5     private $carSpeed=0; //初始化车的速度表值
  6     private $Observers;  //各项车的性能观察对象
  7 
  8     public function __construct($Name){
  9         $this->carName=$Name;
 10         $this->Observers=new SplObjectStorage;
 11     }
 12 
 13     //启动
 14     public function start(){
 15         $this->carState=1;
 16         $this->notify();
 17     }
 18 
 19     //停车
 20     public function stop(){
 21         $this->carState=0;
 22         $this->carSpeed=0;
 23         $this->notify();
 24     }
 25 
 26     //加速
 27     public function accelerate($Acceleration){
 28         if(0===$this->carState){
 29             throw new Exception('Please start!');
 30         }
 31         if(!is_int($Acceleration) || $Acceleration<0){
 32             throw new Exception('The value of acceleration is invalid!');
 33         }
 34         $this->carSpeed+=$Acceleration;
 35         $this->notify();
 36     }
 37 
 38     //增加监测对象
 39     public function attach(SplObserver $observer){
 40         if(!$this->Observers->contains($observer)){
 41             $this->Observers->attach($observer);
 42         }
 43         return true;
 44     }
 45 
 46     //删除监测对象
 47     public function detach(SplObserver $observer){
 48         if(!$this->Observers->contains($observer)){
 49             return false;
 50         }
 51         $this->Observers->detach($observer);
 52         return true;
 53     }
 54 
 55     //传送对象
 56     public function notify(){
 57         foreach($this->Observers as $observer){
 58             $observer->update($this);
 59         }
 60     }
 61 
 62     public function __get($Prop){
 63         switch($Prop){
 64             case 'STATE':
 65                 return $this->carState;
 66                 break;
 67             case 'SPEED':
 68                 return $this->carSpeed;
 69                 break;
 70             case 'NAME':
 71                 return $this->carName;
 72                 break;
 73             default:
 74                 throw new Exception($Prop.'can not be read');
 75         }
 76     }
 77 
 78     public function __set($Prop,$Val){
 79         throw new Exception($Prop.'can not be set');
 80     }
 81 }
 82 
 83 class carStateObserver implements SplObserver{
 84     private $SubjectState;
 85     public function update(SplSubject $subject){
 86         switch($subject->STATE){
 87             case 0:
 88                 if(is_null($this->SubjectState)){
 89                     echo $subject->NAME.' not started'."\n";
 90                 }else{
 91                     echo $subject->NAME.' stalling of engine'."\n";
 92                 }
 93                 $this->SubjectState=0;
 94                 break;
 95             case 1:
 96                 if(1!==$this->SubjectState){
 97                     echo $subject->NAME.' is starting'."\n";
 98                     $this->SubjectState=1;
 99                 }
100                 break;
101             default:
102                 throw new Exception('Unexpected error in carStateObserver::update()');
103         }
104     }
105 }
106 
107 class carSpeedObserver implements SplObserver{
108     public function update(SplSubject $subject){
109         if(0!==$subject->STATE){
110             echo $subject->NAME.' current speed is '.$subject->SPEED.'Kmh'."\n";
111         }
112     }
113 }
114 
115 class carOverspeedObserver implements SplObserver{
116     public function update(SplSubject $subject){
117         if($subject->SPEED>130){
118             throw new Exception('The max speed is 130, you are breaking up!'."\n");
119         }
120     }
121 }
122 
123 try{
124     $driver = new car('AUDIA4');
125     $driver->attach(new carStateObserver);
126     $driver->attach(new carSpeedObserver);
127     $driver->attach(new carOverspeedObserver);
128     $driver->start();
129     $driver->accelerate(10);
130     $driver->accelerate(30);
131     $driver->stop();
132     $driver->start();
133     $driver->accelerate(50);
134     $driver->accelerate(70);
135     $driver->accelerate(100);
136     $driver->accelerate(150);
137 }
138 catch(Exception$e){
139     echo $e->getMessage();
140 }
141 ?>