命令模式

将一个请求封装为一个对象，从而是你可用不同的请求对客户进行参数化，对请求排队或记录请求日志，以及支持可撤销的操作<br />也被称为事务模式<br />举个例子：<br />饭店吃饭，顾客是命令的下达者，服务员是命令的接收者，菜单是整个命令，厨师是命令的执行者<br />这个模式解决了，修改菜单命令的时候，只需要跟服务员说就行了，实现了顾客厨师的解耦，可以实现一个命令接收者，多个命令，（下单，拿酒，上菜），或者把一条命令转达给多个执行者（热菜，凉菜）这个才是命令模式的发挥作用的地方<br />创建执行者，放入命令列表，接收者调用命令 就ok了<br />![image.png](https://cdn.nlark.com/yuque/0/2021/png/22438777/1635477896085-72fa4da1-eebd-4bae-ac21-aee539f1a552.png#clientId=u436079fb-0799-4&from=paste&height=382&id=u4f0fae58&margin=%5Bobject%20Object%5D&name=image.png&originHeight=382&originWidth=817&originalType=binary&ratio=1&size=44009&status=done&style=none&taskId=u4430bdf0-4749-4ac6-aa04-f3acaab3ba6&width=817)

<?php

//命令的请求类
class Invoker
{
    //命令类
    public $command = array();

    //添加命令
    public function addVoker($command)
    {
        $this->command[] = $command;
    }

    //执行命令
    public function exec()
    {
        //命令类的执行方法
        foreach ($this->command as $value) {
            $value->execute();
        }
    }
}

//命令抽象类
abstract class Command
{
    //执行类
    protected $receiver = array();

    //添加执行类
    public function AddCommand($receiver)
    {
        $this->receiver[] = $receiver;
    }

    abstract public function execute();
}

//命令实现类
class ConcreteCommand extends Command
{
    public function execute()
    {
        foreach ($this->receiver as $value) {
            $value->action();
        }
    }
}

//最终的执行类
class ReceiverA
{
    //名字
    public $name;

    public function __construct($name)
    {
        $this->name = $name;
    }

    public function action()
    {
        echo $this->name . '命令执行了！', PHP_EOL;
    }
}

//最终的执行类
class ReceiverB
{
    //名字
    public $name;

    public function __construct($name)
    {
        $this->name = $name;
    }

    public function action()
    {
        echo $this->name . '命令撤销了！', PHP_EOL;
    }
}

//先实例化执行类
$ReceiverA1=new ReceiverA('宫保鸡丁');
$ReceiverA2=new ReceiverA('京酱肉丝');
$ReceiverA3=new ReceiverA('水煮肉片');
$ReceiverB=new ReceiverB('京酱肉丝');

//添加命令
$ConcreteCommand=new ConcreteCommand();
$ConcreteCommand->AddCommand($ReceiverA1);
$ConcreteCommand->AddCommand($ReceiverA2);
$ConcreteCommand->AddCommand($ReceiverA3);

$ConcreteCommand1=new ConcreteCommand();
$ConcreteCommand1->AddCommand($ReceiverB);

//请求类
$Invoker= new Invoker();
$Invoker->addVoker($ConcreteCommand);
$Invoker->addVoker($ConcreteCommand1);
$Invoker->exec();