书中的例子都比较浅显易懂，不过由于是外国佬写的，所以例子的习惯不是很附合中国特色，可能偶尔看起来有些别扭，还有语言习惯也不是中国风。当然看过这本书之后，你才能深刻理解设计模式到底能为你解决哪些问题，不能为你解决哪些问题（比如不能代替你的编码）。
我将书中部分代码改成PHP，看下代码再配合概念应该是比较容易理解了。
策略模式
复制代码代码如下:
<?php
/**
* 策略模式
* 定义了算法族，分别封装起来，让它们之间可以互相替换，
* 此模式让算法的变化独立于使用算法的客户。
*/
//飞行行为接口
interface FlyBehavior {
public function fly();
}
//呱呱叫行为接口
interface QuackBehavior {
public function quack();
}
//翅膀飞行
class FlyWithWings implements FlyBehavior {
public function fly() {
echo "I'm flying!! ";
}
}
//不会飞
class FlyNoWay implements FlyBehavior {
public function fly() {
echo "I can't fly! ";
}
}
class FlyRocketPowered implements FlyBehavior {
public function fly() {
echo "I'm flying with a rocket! ";
}
}
class Qquack implements QuackBehavior {
public function quack() {
echo "Quack ";
}
}
class Squeak implements QuackBehavior {
public function quack() {
echo "Squeak ";
}
}
class MuteQuack implements QuackBehavior {
public function quack() {
echo "<< Silence >> ";
}
}
abstract class Duck {
protected $quack_obj;
protected $fly_obj;
public abstract function display();
public function performQuack() {
$this->quack_obj->quack();
}
public function performFly() {
$this->fly_obj->fly();
}
public function swim() {
echo "All ducks float, even decoys! ";
}
public function setFlyBehavior(FlyBehavior $fb) {
$this->fly_obj = $fb;
}
public function setQuackBehavior(QuackBehavior $qb) {
$this->quack_obj = $qb;
}
}
class ModelDuck extends Duck {
public function __construct() {
$this->fly_obj = new FlyNoWay();
$this->quack_obj = new MuteQuack();
}
public function display() {
echo "I'm a model duck! ";
}
}
$model = new ModelDuck();
$model->performFly();
$model->performQuack();
//提供新的能力
$model->setFlyBehavior(new FlyRocketPowered());
$model->setQuackBehavior(new Squeak());
$model->performFly();
$model->performQuack();
?>
单件模式
复制代码代码如下:
<?php
/**
* 单件模式
* 确保一个类只有一个实例，并提供一个全局访问点。
*/
class MyClass {
private static $uniqueInstance;
private function __construct() {
}
public static function getInstance() {
if (self::$uniqueInstance == null) {
self::$uniqueInstance = new MyClass();
}
return self::$uniqueInstance;
}
}
$myClass = MyClass::getInstance();
var_dump($myClass);
$myClass = MyClass::getInstance();
var_dump($myClass);
?>
工厂方法模式
复制代码代码如下:
<?php
abstract class PizzaStore {
public function orderPizza($type) {
$pizza = $this->createPizza($type);
$pizza->prepare();
$pizza->bake();
$pizza->cut();
$pizza->box();
return $pizza;
}
public abstract function createPizza($type);
}
class NYPizzaStore extends PizzaStore {
public function createPizza($type) {
if ($type == "cheese") {
return new NYStyleCheesePizza();
} elseif ($type == "veggie") {
return new NYStyleVeggiePizza();
} elseif ($type == "clam") {
return new NYStyleClamPizza();
} elseif ($type == "papperoni") {
return new NYStylePapperoniPizza();
} else {
return null;
}
}
}
class ChicagoPizzaStore extends PizzaStore {
public function createPizza($type) {
if ($type == "cheese") {
return new ChicagoStyleCheesePizza();
} elseif ($type == "veggie") {
return new ChicagoStyleVeggiePizza();
} elseif ($type == "clam") {
return new ChicagoStyleClamPizza();
} elseif ($type == "papperoni") {
return new ChicagoStylePapperoniPizza();
} else {
return null;
}
}
}
abstract class Pizza {
public $name;
public $dough;
public $sauce;
public $toppings = array();
public function prepare() {
echo "Preparing " . $this->name . " ";
echo "Yossing dough... ";
echo "Adding sauce... ";
echo "Adding toppings: ";
for ($i = 0; $i < count($this->toppings); $i++) {
echo " " . $this->toppings[$i] . " ";
}
}
public function bake() {
echo "Bake for 25 minutes at 350 ";
}
public function cut() {
echo "Cutting the pizza into diagonal slices ";
}
public function box() {
echo "Place pizza in official PizzaStore box ";
}
public function getName() {
return $this->name;
}
}
class NYStyleCheesePizza extends Pizza {
public function __construct() {
$this->name = "NY Style Sauce and cheese Pizza";
$this->dough = "Thin Crust Dough";
$this->sauce = "Marinara Sauce";
$this->toppings[] = "Grated Reggiano Cheese";
}
}
class NYStyleVeggiePizza extends Pizza {
public function __construct() {
$this->name = "NY Style Sauce and veggie Pizza";
$this->dough = "Thin Crust Dough";
$this->sauce = "Marinara Sauce";
$this->toppings[] = "Grated Reggiano veggie";
}
}
class NYStyleClamPizza extends Pizza {
public function __construct() {
$this->name = "NY Style Sauce and clam Pizza";
$this->dough = "Thin Crust Dough";
$this->sauce = "Marinara Sauce";
$this->toppings[] = "Grated Reggiano clam";
}
}
class NYStylePapperoniPizza extends Pizza {
public function __construct() {
$this->name = "NY Style Sauce and papperoni Pizza";
$this->dough = "Thin Crust Dough";
$this->sauce = "Marinara Sauce";
$this->toppings[] = "Grated Reggiano papperoni";
}
}
class ChicagoStyleCheesePizza extends Pizza {
public function __construct() {
$this->name = "Chicago Style Deep Dish Cheese Pizza";
$this->dough = "Extra Thick Crust Dough";
$this->sauce = "Plum Tomato Sauce";
$this->toppings[] = "Shredded Mozzarella Cheese";
}
public function cut() {
echo "Cutting the pizza into square slices ";
}
}
$myStore = new NYPizzaStore();
$chicagoStore = new ChicagoPizzaStore();
$pizza = $myStore->orderPizza("cheese");
echo "Ethan ordered a " . $pizza->getName() . " ";
$pizza = $chicagoStore->orderPizza("cheese");
echo "Ethan ordered a " . $pizza->getName() . " ";
?>
工厂模式
复制代码代码如下:
<?php
abstract class PizzaStore {
public function orderPizza($type) {
$pizza = $this->createPizza($type);
$pizza->prepare();
$pizza->bake();
$pizza->cut();
$pizza->box();
return $pizza;
}
public abstract function createPizza($type);
}
class NYPizzaStore extends PizzaStore {
public function createPizza($type) {
$pizza = null;
$ingredientFactory = new NYPizzaIngredientFactory();
if ($type == "cheese") {
$pizza = new CheesePizza($ingredientFactory);
$pizza->setName('New York Style Cheese Pizza');
} elseif ($type == "veggie") {
$pizza = new VeggiePizza($ingredientFactory);
$pizza->setName('New York Style Veggie Pizza');
} elseif ($type == "clam") {
$pizza = new ClamPizza($ingredientFactory);
$pizza->setName('New York Style Clam Pizza');
} elseif ($type == "papperoni") {
$pizza = new PapperoniPizza($ingredientFactory);
$pizza->setName('New York Style Papperoni Pizza');
}
return $pizza;
}
}
class ChicagoPizzaStore extends PizzaStore {
public function createPizza($type) {
if ($type == "cheese") {
return new ChicagoStyleCheesePizza();
} elseif ($type == "veggie") {
return new ChicagoStyleVeggiePizza();
} elseif ($type == "clam") {
return new ChicagoStyleClamPizza();
} elseif ($type == "papperoni") {
return new ChicagoStylePapperoniPizza();
} else {
return null;
}
}
}
interface PizzaIngredientFactory {
public function createDough();
public function createSauce();
public function createCheese();
public function createVeggies();
public function createPepperoni();
public function createClam();
}
class NYPizzaIngredientFactory implements PizzaIngredientFactory {
public function createDough() {
return new ThinCrustDough();
}
public function createSauce() {
return new MarinaraSauce();
}
public function createCheese() {
return new ReggianoCheese();
}
public function createVeggies() {
$veggies = array(
new Garlic(),
new Onion(),
new Mushroom(),
new RedPepper(),
);
return $veggies;
}
public function createPepperoni() {
return new SlicedPepperoni();
}
public function createClam() {
return new FreshClams();
}
}
class ChicagoPizzaIngredientFactory implements PizzaIngredientFactory {
public function createDough() {
return new ThickCrustDough();
}
public function createSauce() {
return new PlumTomatoSauce();
}
public function createCheese() {
return new Mozzarella();
}
public function createVeggies() {
$veggies = array(
new BlackOlives(),
new Spinach(),
new EggPlant(),
);
return $veggies;
}
public function createPepperoni() {
return new SlicedPepperoni();
}
public function createClam() {
return new FrozenClams();
}
}
abstract class Pizza {
public $name;
public $dough;
public $sauce;
public $veggies = array();
public $cheese;
public $pepperoni;
public $clam;
public abstract function prepare();
public function bake() {
echo "Bake for 25 minutes at 350 ";
}
public function cut() {
echo "Cutting the pizza into diagonal slices ";
}
public function box() {
echo "Place pizza in official PizzaStore box ";
}
public function getName() {
return $this->name;
}
public function setName($name) {
$this->name = $name;
}
public function __toString() {
}
}
class CheesePizza extends Pizza {
public $ingredientFactory;
public function __construct(PizzaIngredientFactory $ingredientFactory) {
$this->ingredientFactory = $ingredientFactory;
}
public function prepare() {
echo "Preparing " . $this->name . " ";
$this->dough = $this->ingredientFactory->createDough();
$this->sauce = $this->ingredientFactory->createSauce();
$this->cheese = $this->ingredientFactory->createCheese();
}
}
class ClamPizza extends Pizza {
public $ingredientFactory;
public function __construct(PizzaIngredientFactory $ingredientFactory) {
$this->ingredientFactory = $ingredientFactory;
}
public function prepare() {
echo "Preparing " . $this->name . " ";
$this->dough = $this->ingredientFactory->createDough();
$this->sauce = $this->ingredientFactory->createSauce();
$this->cheese = $this->ingredientFactory->createCheese();
$clam = $this->ingredientFactory->createClam();
}
}
$nyPizzaStore = new NYPizzaStore();
$nyPizzaStore->orderPizza('cheese');
?>
观察者模式
复制代码代码如下:
<?php
/**
* 观察者模式
* 定义了对象之间的一对多依赖，当一个对象改变状态时，
* 它的所有依赖者都会收到通知并自动更新。
*/
interface Subject {
public function registerObserver(Observer $o);
public function removeObserver(Observer $o);
public function notifyObservers();
}
interface Observer {
public function update($temperature, $humidity, $pressure);
}
interface DisplayElement {
public function display();
}
class WeatherData implements Subject {
private $observers = array();
private $temperature;
private $humidity;
private $pressure;
public function __construct() {
$this->observers = array();
}
public function registerObserver(Observer $o) {
$this->observers[] = $o;
}
public function removeObserver(Observer $o) {
if (($key = array_search($o, $this->observers)) !== false) {
unset($this->observers[$key]);
}
}
public function notifyObservers() {
foreach ($this->observers as $observer) {
$observer->update($this->temperature, $this->humidity, $this->pressure);
}
}
public function measurementsChanged() {
$this->notifyObservers();
}
public function setMeasurements($temperature, $humidity, $pressure) {
$this->temperature = $temperature;
$this->humidity = $humidity;
$this->pressure = $pressure;
$this->measurementsChanged();
}
}
class CurrentConditionsDisplay implements Observer, DisplayElement {
private $temperature;
private $humidity;
private $weatherData;
public function __construct(Subject $weatherData) {
$this->weatherData = $weatherData;
$weatherData->registerObserver($this);
}
public function update($temperature, $humidity, $pressure) {
$this->temperature = $temperature;
$this->humidity = $humidity;
$this->display();
}
public function display() {
echo "温度：" . $this->temperature . "; 湿度：" . $this->humidity . "% ";
}
}
class StatistionsDisplay implements Observer, DisplayElement {
private $temperature;
private $humidity;
private $pressure;
private $weatherData;
public function __construct(Subject $weatherData) {
$this->weatherData = $weatherData;
$weatherData->registerObserver($this);
}
public function update($temperature, $humidity, $pressure) {
$this->temperature = $temperature;
$this->humidity = $humidity;
$this->pressure = $pressure;
$this->display();
}
public function display() {
echo "温度：" . $this->temperature . "; 湿度：" . $this->humidity . "%; 气压：" . $this->pressure . " ";
}
}
$weatherData = new WeatherData();
$currentDisplay = new CurrentConditionsDisplay($weatherData);
$statistionDisplay = new StatistionsDisplay($weatherData);
$weatherData->setMeasurements(10, 20, 30);
$weatherData->removeObserver($currentDisplay);
$weatherData->setMeasurements(30, 40, 50);
?>
命令模式
复制代码代码如下:
<?php
class Light {
public function __construct() {
}
public function on() {
echo "Light On ";
}
public function off() {
echo "Light Off ";
}
}
interface Command {
public function execute();
}
class LightOnCommand implements Command {
public $light;
public function __construct(Light $light) {
$this->light = $light;
}
public function execute() {
$this->light->on();
}
}
class SimpleRemoteControl {
public $slot;
public function __construct() {
}
public function setCommand(Command $command) {
$this->slot = $command;
}
public function buttonWasPressed() {
$this->slot->execute();
}
}
class RemoteControlTest {
public static function main() {
$remote = new SimpleRemoteControl();
$light = new Light();
$lightOn = new LightOnCommand($light);
$remote->setCommand($lightOn);
$remote->buttonWasPressed();
}
}
RemoteControlTest::main();
?>
装饰者模式
复制代码代码如下:
<?php
/**
* 装饰着模式
* 动态地将责任附加到对象上，若要扩展功能，装饰者提供了比继承更有弹性的替代方案。
*/
abstract class Beverage {
public $description = "Unknown Beverage";
public function getDescription() {
return $this->description;
}
public abstract function cost();
}
abstract class CondimentDecorator extends Beverage {
//JAVA代码里这里是个抽象类，PHP不允许这么做
public function getDescription() {
return $this->description;
}
}
class Espresso extends Beverage {
public function __construct() {
$this->description = "Espresso";
}
public function cost() {
return 1.99;
}
}
class HouseBlend extends Beverage {
public function __construct() {
$this->description = "HouseBlend";
}
public function cost() {
return .89;
}
}
class DarkRoast extends Beverage {
public function __construct() {
$this->description = "DarkRoast";
}
public function cost() {
return .99;
}
}
class Mocha extends CondimentDecorator {
public $beverage;
public function __construct(Beverage $beverage) {
$this->beverage = $beverage;
}
public function getDescription() {
return $this->beverage->getDescription() . ", Mocha";
}
public function cost() {
return .20 + $this->beverage->cost();
}
}
class Whip extends CondimentDecorator {
public $beverage;
public function __construct(Beverage $beverage) {
$this->beverage = $beverage;
}
public function getDescription() {
return $this->beverage->getDescription() . ", Whip";
}
public function cost() {
return .10 + $this->beverage->cost();
}
}
class Soy extends CondimentDecorator {
public $beverage;
public function __construct(Beverage $beverage) {
$this->beverage = $beverage;
}
public function getDescription() {
return $this->beverage->getDescription() . ", Soy";
}
public function cost() {
return .15 + $this->beverage->cost();
}
}
$beverage = new Espresso();
echo $beverage->getDescription() . " ";
$beverage2 = new DarkRoast();
$beverage2 = new Mocha($beverage2);
$beverage2 = new Mocha($beverage2);
$beverage2 = new Whip($beverage2);
echo $beverage2->getDescription() . " $" . $beverage2->cost() . " ";
$beverage3 = new HouseBlend();
$beverage3 = new Soy($beverage3);
$beverage3 = new Mocha($beverage3);
$beverage3 = new Whip($beverage3);
echo $beverage3->getDescription() . " $" . $beverage3->cost() . " ";
?>
状态模式
复制代码代码如下:
<?php
class GumballMachine {
const SOLD_OUT = 0;
const NO_QUARTER = 1;
const HAS_QUARTER = 2;
const SOLD = 3;
public $state = self::SOLD_OUT;
public $count = 0;
public function __construct($count) {
$this->count = $count;
if ($count > 0) {
$this->state = self::NO_QUARTER;
}
}
public function insertQuarter() {
if ($this->state == self::HAS_QUARTER) {
echo "You can't insert another quarter! ";
} else if ($this->state == self::NO_QUARTER) {
$this->state = self::HAS_QUARTER;
echo "You inserted a quarter! ";
} else if ($this->state == self::SOLD_OUT) {
echo "You can't insert a quarter, the machine is sold out! ";
} else if ($this->state == self::SOLD) {
echo "Please wait, we're already giving you a gumball! ";
}
}
}
$obj = new GumballMachine(0);
print_r($obj)
?>