《Head First设计模式》读书笔记（一）

最新推荐文章于 2025-01-08 21:58:45 发布

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#设计模式 #读书 #null #php

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本文通过PHP代码示例介绍了策略模式和观察者模式的应用。策略模式允许算法独立于使用它的客户端而变化，通过定义一系列算法，并将每个算法封装起来。观察者模式则是一种对象行为模式，它定义了对象间的一种一对多依赖关系，当一个对象的状态发生改变时，所有依赖于它的对象都会得到通知并被自动更新。

用php来实现书中的示例和习题，昨天完成策略模式和观察者模式，代码如下：

代码

<?php
    interface FlyBehavior
    {
        function fly();
    }
    interface QuackBehavior
    {
        function quack();
    }
    class FlyWithWings implements FlyBehavior
    {
        public function fly()
        {
            print("fly with wings/n");
        }
    }
    class FlyNoWay implements FlyBehavior
    {
        public function fly()
        {
            print("fly no way/n");
        }
    }
    class Quack implements QuackBehavior
    {
        public function quack()
        {
            print("quack,gua,gua/n");
        }
    }
    abstract class Duck
    {
        protected $flyBehavior = null;
        protected $quackBehaviro = null;
        public function __construct(FlyBehavior $flyBehavior = null, QuackBehavior $quackBehavior = null)
        {
            $this->setFlyBehavior($flyBehavior);
            $this->setQuackBehavior($quackBehavior);
        }
        public function fly()
        {
            $this->flyBehavior->fly();
        }
        public function quack()
        {
            $this->quackBehavior->quack();
        }
        public function getFlyBehavior()
        {
            return $flyBehavior;
        }
        public function setFlyBehavior(FlyBehavior $fly)
        {
            $this->flyBehavior = $fly;
        }
        public function getQuackBehavior()
        {
            return $quackBehavior;
        }
        public function setQuackBehavior(QuackBehavior $quack)
        {
            $this->quackBehavior = $quack;
        }
        abstract public function display();
    }
    class RedheadDuck extends Duck
    {
        public function __construct(FlyBehavior $flyBehavior = null, QuackBehavior $quackBehavior = null)
        {
            parent::__construct($flyBehavior, $quackBehavior);
        }
        public function display()
        {
            print("damn it! RedheadDuck display()/n");
        }
    }
    $duck = new RedheadDuck();
    $duck->setFlyBehavior(new FlyWithWings());
    $duck->setQuackBehavior(new Quack());
    $duck->fly();
    $duck->quack();
    $duck->display();
?>

代码

<?php
    abstract class Character
    {
        protected $weapon = null;
        public function __construct(WeaponBehavior $weapon = null)
        {
            $this->setWeapon($weapon);
        }
        public function setWeapon(WeaponBehavior $weapon)
        {
            $this->weapon = $weapon;
        }
        public function getWeapon()
        {
            return $this->weapon;
        }
        public function useWeapon()
        {
            $this->weapon->useWeapon();
        }
    }
    class Knight extends Character
    {
    }
    class Queen extends Character
    {
    }
    interface WeaponBehavior
    {
        function useWeapon();
    }
    class KnifeWeapon implements WeaponBehavior
    {
        public function useWeapon()
        {
            print("Knife used/n");
        }
    }
    $man = new Knight();
    $man->setWeapon(new KnifeWeapon());
    $man->useWeapon();
?>

代码

<?php
    interface Observable
    {
        function addObserver(Observer $observer);
        function removeObserver(Observer $observer);
        function notifyServers();
    }
    interface Observer
    {
        function update(WeatherData $weatherData);
    }
    class WeatherData implements Observable
    {
        private $observers = array();
        private $temperature = 0;
        private $humidity = 0;
        private $pressure = 0;
        public function getTemperature()
        {
            return $this->temperature;
        }
        public function setTemperature($temp)
        {
            $this->temperature = $temp;
        }
        public function getHumidity()
        {
            return $this->humidity;
        }
        public function setHumidity($humidity)
        {
            $this->humidity = $humidity;
        }
        public function getPressure()
        {
            return $this->pressure;
        }
        public function setPressure($pressure)
        {
            $this->pressure = $pressure;
        }
        public function setMeasurements($temperature, $humidity, $pressure)
        {
            $this->setTemperature($temperature);
            $this->setHumidity($humidity);
            $this->setPressure($pressure);
            $this->measureChanged();
        }
        public function measureChanged()
        {
            $this->notifyServers();
        }
        public function addObserver(Observer $observer)
        {
            $this->observers[] = $observer;
        }
        public function removeObserver(Observer $observer)
        {
            $result = array();
            foreach ($this->observers as $obj) {
                if ($obj !== $observer) {
                    $result[] = $obj;
                }
            }
            unset($this->observers);
            $this->observers = $result;
        }
        public function notifyServers()
        {
            foreach ($this->observers as $observer) {
                $observer->update($this);
            }
        }
        public function getObservers()
        {
            return $this->observers;
        }
    }
    interface Displayable
    {
        function display();
    }
    abstract class BaseDisplay implements Observer, Displayable
    {
        private $weatherData = null;
        public function __construct(Observable $weatherData = null)
        {
            $this->weatherData = $weatherData;
            if ($weatherData != null) {
                $this->weatherData->addObserver($this);
            }
        }
        public function update(WeatherData $weatherData)
        {
        }
        public function display()
        {
        }
    }
    class CurrentConditionDisplay extends BaseDisplay
    {
        private $weatherData = null;
        private $temperature = 0;
        private $humidity = 0;
        private $pressure = 0;
        public function __construct(Observable $weatherData = null)
        {
            $this->weatherData = $weatherData;
            if ($weatherData != null) {
                $this->weatherData->addObserver($this);
            }
        }
        public function update(WeatherData $weatherData)
        {
            $this->temperature = $weatherData->getTemperature();
            $this->humidity = $weatherData->getHumidity();
            $this->pressure = $weatherData->getPressure();
            $this->display();
        }
        public function display()
        {
            print("temp: " . $this->temperature . ", humi: " . $this->humidity . ", pressure: " . $this->pressure . "/n");
        }
    }
    class GeneralDisplay extends BaseDisplay
    {

        public function update(WeatherData $weatherData)
        {
            $this->display();
        }
        public function display()
        {
            print("GeneralDisplay().display/n");
        }
    }
    $weatherData = new WeatherData();

    $display = new CurrentConditionDisplay($weatherData);
    $display2 = new GeneralDisplay($weatherData);
    $weatherData->setMeasurements(20,30,40);
    $weatherData->removeObserver($display2);
    print("after.../n");
    $weatherData->setMeasurements(33,44,55);
?>