详解PHP设计模式之委托模式

<?php 
//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
namespace Tools;
/*
委托模式
去除核心对象中的判决和复杂功能性
*/

//委托接口
interface Delegate{
public function playList($list,$song);
}
//mp3处理类
class mp3 implements Delegate{
public function playList($list,$song){
return $list[$song].&#39;.mp3&#39;;
}
}
//mp4处理类
class mp4 implements Delegate{
public function playList($list, $song)
{
return $list[$song].&#39;.mp4&#39;;
}
}
class cdDelegate{
protected $cdInfo = array();

public function addSong($song){
$this->cdInfo[$song] = $song;
}

public function play($type,$song){
$name = &#39;\Tools\\&#39;.$type;
$obj = new $name;
return $obj->playList($this->cdInfo,$song);
}
}
$newCd = new cdDelegate();
$newCd->addSong("1");
$newCd->addSong("2");
$newCd->addSong("3");
echo $newCd->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