Mediator_中介者模式_PHP语言描述

中介者模式，我的理解是，你的项目中存在许多级别平等的同事类实例，并且这些实例之间都需要有不同程度的各种交互操作活动。这个时候可以使用中介者模式来降低各同事类的耦合程度，每个同事类都只关心自己需要做什么，把耦合交互的工作交给中介类来完成。这里用了一个模拟电脑播放CD的例子来讲述这个问题。

这是一个标准定义中得中介者模式用例，在实际应用着，可能不需要所有的同事类都继承于一个父类，也不一定中介者类必须持有所有的同事用类。更多的时候中介者实例可能会用Singleton单例模式来设计。

1<?php
2 //抽象的同事类
3 abstract class Colleague{
4  private $mediator;
5  
6  public function __construct($mediator){
7   if($mediator instanceof Mediator)
8   {
9    $this->mediator = $mediator;
10   }
11   else {
12    trigger_error("Input Object isn't Mediator Class Object!",E_USER_ERROR);
13   }
14  }
15  
16  public function getMediator(){
17   return $this->mediator;
18  }
19 }
20 
21 //CD驱动器类
22 class CDDriver extends Colleague{
23  public function __construct($mediator){
24   parent::__construct($mediator);
25  }
26  
27  //数据变量
28  private $data;
29  
30  //获取光驱读取出来的数据
31  public function getData(){
32   return $this->data;
33  }
34  
35  //读取光盘
36  public function readCD(){
37   $this->data = "设计模式,值得好好研究";
38   //通知主板，自己的状态发生了改变
39   $this->getMediator()->changed($this);
40  }
41  
42 }
43 
44 //CPU类
45 class CPU extends Colleague{
46  public function __construct($mediator){
47   parent::__construct($mediator);
48  }
49  //视频数据
50  private $videoData;
51  //声音数据
52  private $soundData;
53  
54  public function getVideoData(){
55   return $this->videoData;
56  }
57  
58  public function getSoundData(){
59   return $this->soundData;
60  }
61  
62  public function executeData($data){
63   $dataArr = explode(",", $data);
64   $this->videoData = $dataArr[0];
65   $this->soundData = $dataArr[1];
66   $this->getMediator()->changed($this);
67  }
68 }
69 
70 //显卡类
71 class VideoCard extends Colleague{
72  public function __construct($mediator){
73   parent::__construct($mediator);
74  }
75  public function showData($data){
76   echo '您现在观看的是:'.$data;
77  }
78 }
79 
80 //声卡类
81 class SoundCard extends Colleague{
82  public function __construct($mediator){
83   parent::__construct($mediator);
84  }
85  public function showData($data){
86   echo '画外音:'.$data;
87  }
88 }
89 
90 //定义中介者模式接口
91 interface Mediator{
92  public function changed($colleague);
93 }
94 
95 class MotherBoard implements Mediator{
96  //定于中介对象需要掌握的所有需要交互的同事类
97  private $cdDriver,$cpu,$videoCard,$soundCard;
98  
99  public function setCdDriver($cdDriver){
100   $this->cdDriver = $cdDriver;
101  }
102  
103  public function setCPU($cpu){
104   $this->cpu = $cpu;
105  }
106  
107  public function setVideoCard($videoCard){
108   $this->videoCard = $videoCard;
109  }
110  
111  public function setSoundCard($soundCard){
112   $this->soundCard = $soundCard;
113  }
114  
115  public function changed($colleague){
116   if($colleague instanceof CDDriver){
117    $this->opeCDDriverReadData($colleague);
118   }
119   else if($colleague instanceof CPU){
120    $this->opeCPU($colleague);
121   }
122  }
123  
124  private function opeCDDriverReadData($cd){
125   $data = $cd->getData();
126   $this->cpu->executeData($data);
127  }
128  
129  private function opeCPU($cpu){
130   $videoData = $cpu->getVideoData();
131   $soundData = $cpu->getSoundData();
132   $this->videoCard->showData($videoData);
133   echo '<br>';
134   $this->soundCard->showData($soundData);
135  }
136 }
137 
138 //创建中介对象：主板
139 $mediator = new MotherBoard();
140 //创建各同事类:CD驱动，CPU,显卡,声卡
141 $cd = new CDDriver($mediator);
142 $cpu = new CPU($mediator);
143 $videoCard = new VideoCard($mediator);
144 $soundCard = new SoundCard($mediator);
145 //让中介类知道所有需要交互的同事类
146 $mediator->setCdDriver($cd);
147 $mediator->setCPU($cpu);
148 $mediator->setSoundCard($soundCard);
149 $mediator->setVideoCard($videoCard);
150 
151 $cd->readCD();
152?>