Detaillierte Erklärung und Fälle des PHP-Delegierungsmodus

<?php  
//委托模式-去除核心对象中的判决和复杂的功能性  
//使用委托模式之前，调用cd类，选择cd播放模式是复杂的选择过程  
class cd {  
    protected $cdInfo = array();   
      
    public function addSong($song) {  
        $this->cdInfo[$song] = $song;  
    }  
      
    public function playMp3($song) {  
        return $this->cdInfo[$song] . &#39;.mp3&#39;;  
    }  
      
    public function playMp4($song) {  
        return $this->cdInfo[$song] . &#39;.mp4&#39;;  
    }  
}  
$oldCd = new cd;  
$oldCd->addSong("1");  
$oldCd->addSong("2");  
$oldCd->addSong("3");  
$type = &#39;mp3&#39;;  
if ($type == &#39;mp3&#39;) {  
    $oldCd->playMp3();  
} else {  
    $oldCd->playMp4();  
}

<?php  
//委托模式-去除核心对象中的判决和复杂的功能性  
//改进cd类  
class cdDelegate {  
    protected $cdInfo = array();   
      
    public function addSong($song) {  
        $this->cdInfo[$song] = $song;  
    }  
      
    public function play($type, $song) {  
        $obj = new $type;  
        return $obj->playList($this->cdInfo, $song);  
    }  
}  
  
class mp3 {  
    public function playList($list) {  
        return $list[$song];  
    }  
}  
  
class mp4 {  
    public function playList($list) {  
        return $list[$song];  
    }  
}  
  
$newCd = new cd;  
$newCd->addSong("1");  
$newCd->addSong("2");  
$newCd->addSong("3");  
$type = &#39;mp3&#39;;  
$oldCd->play(&#39;mp3&#39;, &#39;1&#39;); //只要传递参数就能知道需要选择何种播放模式