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设计模式php实现

2026-02-15 20:37:55PHP

设计模式在PHP中的实现

设计模式是解决常见软件设计问题的可重用方案。在PHP中实现设计模式可以提高代码的可维护性、可扩展性和复用性。以下是几种常见设计模式及其PHP实现示例。

单例模式（Singleton）

单例模式确保一个类只有一个实例，并提供一个全局访问点。

class Singleton {
    private static $instance;

    private function __construct() {}

    public static function getInstance() {
        if (null === static::$instance) {
            static::$instance = new static();
        }
        return static::$instance;
    }

    private function __clone() {}
    private function __wakeup() {}
}

工厂模式（Factory）

工厂模式定义一个用于创建对象的接口，让子类决定实例化哪一个类。

interface Product {
    public function getName();
}

class ConcreteProductA implements Product {
    public function getName() {
        return 'Product A';
    }
}

class ConcreteProductB implements Product {
    public function getName() {
        return 'Product B';
    }
}

class ProductFactory {
    public static function createProduct($type) {
        switch ($type) {
            case 'A':
                return new ConcreteProductA();
            case 'B':
                return new ConcreteProductB();
            default:
                throw new Exception('Invalid product type');
        }
    }
}

观察者模式（Observer）

观察者模式定义对象间的一对多依赖关系，当一个对象状态改变时，所有依赖它的对象都会得到通知。

interface Observer {
    public function update($data);
}

interface Subject {
    public function attach(Observer $observer);
    public function detach(Observer $observer);
    public function notify();
}

class ConcreteSubject implements Subject {
    private $observers = [];
    private $data;

    public function attach(Observer $observer) {
        $this->observers[] = $observer;
    }

    public function detach(Observer $observer) {
        $key = array_search($observer, $this->observers, true);
        if ($key !== false) {
            unset($this->observers[$key]);
        }
    }

    public function notify() {
        foreach ($this->observers as $observer) {
            $observer->update($this->data);
        }
    }

    public function setData($data) {
        $this->data = $data;
        $this->notify();
    }
}

class ConcreteObserver implements Observer {
    public function update($data) {
        echo "Received update with data: " . $data . "\n";
    }
}

策略模式（Strategy）

策略模式定义一系列算法，将每个算法封装起来，并使它们可以互相替换。

interface PaymentStrategy {
    public function pay($amount);
}

class CreditCardPayment implements PaymentStrategy {
    public function pay($amount) {
        echo "Paying $amount via Credit Card\n";
    }
}

class PayPalPayment implements PaymentStrategy {
    public function pay($amount) {
        echo "Paying $amount via PayPal\n";
    }
}

class ShoppingCart {
    private $paymentStrategy;

    public function setPaymentStrategy(PaymentStrategy $strategy) {
        $this->paymentStrategy = $strategy;
    }

    public function checkout($amount) {
        $this->paymentStrategy->pay($amount);
    }
}

适配器模式（Adapter）

适配器模式将一个类的接口转换成客户希望的另一个接口。

interface Target {
    public function request();
}

class Adaptee {
    public function specificRequest() {
        return "Specific request";
    }
}

class Adapter implements Target {
    private $adaptee;

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

    public function request() {
        return $this->adaptee->specificRequest();
    }
}

装饰器模式（Decorator）

装饰器模式动态地给一个对象添加一些额外的职责。

设计模式php实现

interface Component {
    public function operation();
}

class ConcreteComponent implements Component {
    public function operation() {
        return "ConcreteComponent";
    }
}

abstract class Decorator implements Component {
    protected $component;

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

    public function operation() {
        return $this->component->operation();
    }
}

class ConcreteDecoratorA extends Decorator {
    public function operation() {
        return "DecoratorA(" . parent::operation() . ")";
    }
}

class ConcreteDecoratorB extends Decorator {
    public function operation() {
        return "DecoratorB(" . parent::operation() . ")";
    }
}