每天认识一种设计模式之工厂方法模式

<?php
// -------------------- 产品接口 --------------------
interface PaymentGateway {
    public function pay(float $amount): string;
}

// -------------------- 具体产品 --------------------
class Alipay implements PaymentGateway {
    public function pay(float $amount): string {
        return "支付宝支付成功：¥" . $amount;
    }
}

class WechatPay implements PaymentGateway {
    public function pay(float $amount): string {
        return "微信支付成功：¥" . $amount;
    }
}

// -------------------- 创建者抽象 --------------------
abstract class PaymentFactory {
    // 工厂方法（核心）
    abstract public function createPayment(): PaymentGateway;

    // 可包含通用业务逻辑
    public function processOrder(float $amount): string {
        $payment = $this->createPayment();
        return $payment->pay($amount);
    }
}

// -------------------- 具体创建者 --------------------
class AlipayFactory extends PaymentFactory {
    public function createPayment(): PaymentGateway {
        return new Alipay();
    }
}

class WechatPayFactory extends PaymentFactory {
    public function createPayment(): PaymentGateway {
        return new WechatPay();
    }
}

// -------------------- 客户端使用 --------------------
function clientCode(PaymentFactory $factory, float $amount) {
    echo $factory->processOrder($amount) . PHP_EOL;
}

// 使用支付宝
clientCode(new AlipayFactory(), 100.50);

// 使用微信支付
clientCode(new WechatPayFactory(), 200.00);

/* 输出：
支付宝支付成功：¥100.5
微信支付成功：¥200
*/