命令模式-PHP

• 烤串
• 开关灯

烤串

烧烤店里，顾客告诉服务员需要的食物，服务器会通知师傅烤串。

这样师傅无须知道是谁点的烤串，顾客也无须知道是谁来烤串。

师傅只需要烤就完事，顾客只需要吃就完事。

师傅与顾客解耦。

<?php
// 烤串
class Barbecuer {
    public function bakeMutton() {
        echo '烤羊肉串\n';
    }
    public function bakeChickenWing() {
        echo '烤鸡翅\n';
    }
}

// 抽象命令
abstract class Command {
    protected $receiver;

    function __construct(Barbecuer $receiver) {
        $this->receiver = $receiver;
    }

    abstract public function excuteCommand();
}

// 烤羊肉
class BakeMuttonCommand extends Command {
    public function excuteCommand() {
        $this->receiver->bakeMutton();
    }
}

// 烤鸡翅
class BakeChickenWingCommand extends Command {
    public function excuteCommand() {
        $this->receiver->bakeChickenWing();
    }
}

// 服务员
class Waiter {
    private $commands = [];

    // 设置订单
    public function setOrder(Command $command) {
        if ($command instanceof bakeChickenWingCommand) {
            echo '服务员: 鸡翅没有了，请点别的烧烤\n';
        } else {
            echo '增加订单\n';
            array_push($this->commands, $commands);
        }
    }

    // 取消订单
    public function cancelOrder(Command $command) {}
    
    // 通知执行
    public function notify() {
        foreach ($this->commands as $value) {
            $value->excuteCommand();
        }
    }
}

// 客户端代码

// 开店前的准备
$boy = new Barbecuer();
$bakeMuttonCommand1 = new BakeMuttonCommand($boy);
$bakeMuttonCommand2 = new BakeMuttonCommand($boy);
$bakeChickenWingCommand1 = new BakeChickenWingCommand($boy);
$girl = new Waiter();

//开门营业
$girl->setOrder($bakeMuttonCommand1); // 增加订单
$girl->setOrder($bakeMuttonCommand2); // 增加订单
$girl->setOrder($bakeChickenWingCommand1); // 服务员: 鸡翅没有了，请点别的烧烤
$girl->notify();

开关灯

通过开关，来控制灯的状态。

<?php
// Receiver
class Bulb {
  public function turnOn() {
    echo "Bulb has been lit";
  }

  public function turnOff() {
    echo "Darkness!";
  }
}

interface Command {
  public function execute();
  public function undo();
  public function redo();
}

// Command
class TurnOn implements Command {
  protected $bulb;

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

  public function execute() {
    $this->bulb->turnOn();
  }

  public function undo() {
    $this->bulb->turnOff();
  }

  public function redo() {
    $this->execute();
  }
}

class TurnOff implements Command {
  protected $bulb;

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

  public function execute() {
    $this->bulb->turnOff();
  }

  public function undo() {
    $this->bulb->turnOn();
  }

  public function redo() {
    $this->execute();
  }
}

// Invoker
class RemoteControl {
  public function submit(Command $command) {
    $command->execute();
  }
}

// client
$bulb = new Bulb();

$turnOn = new TurnOn($bulb);
$turnOff = new TurnOff($bulb);

$remote = new RemoteControl();
$remote->submit($turnOn); // Bulb has been lit!
$remote->submit($turnOff); // Darkness!