Home Backend Development PHP Tutorial Detailed explanation of the delegation pattern of PHP design patterns

Detailed explanation of the delegation pattern of PHP design patterns

Jan 05, 2018 pm 05:55 PM
php model Design Patterns

委托是对一个类的功能进行扩展和复用的方法。它的做法是:写一个附加的类提供附加的功能,并使用原来的类的实例提供原有的功能,接下来通过本文给大家介绍PHP委托设计模式实例详解,感兴趣的朋友一起学习吧。希望对大家有所帮助。

模式定义

委托是对一个类的功能进行扩展和复用的方法。它的做法是:写一个附加的类提供附加的功能,并使用原来的类的实例提供原有的功能。

假设我们有一个 TeamLead 类,将其既定任务委托给一个关联辅助对象 JuniorDeveloper 来完成:本来 TeamLead 处理 writeCode 方法,Usage 调用 TeamLead 的该方法,但现在 TeamLead 将 writeCode 的实现委托给 JuniorDeveloper 的 writeBadCode 来实现,但 Usage 并没有感知在执行 writeBadCode 方法。

设计了一个cd类,类中有mp3播放模式,和mp4播放模式
改进前,使用cd类的播放模式,需要在实例化的类中去判断选择什么方式的播放模式
改进后,播放模式当做一个参数传入playList函数中,就自动能找到对应需要播放的方法。

一,未改进前

<?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(); 
}
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二、通过委托模式,改进后的cd类

<?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
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详解PHP设计模式之备忘录模式

详解PHP设计模式之建造者模式

PHP设计模式之迭代器模式详解

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