PHP 设计模式：工厂模式与策略模式实现

设计模式让代码更灵活、可维护。

1. 工厂模式

interface Logger {

    public function log(string $message): void;

}



class FileLogger implements Logger {

    public function log(string $message): void {

        file_put_contents('/tmp/app.log', $message . PHP_EOL, FILE_APPEND);

    }

}



class LoggerFactory {

    public static function create(string $type): Logger {

        return match ($type) {

            'file' => new FileLogger(),

            'database' => new DatabaseLogger(),

            default => throw new InvalidArgumentException('未知类型')

        };

    }

}

// 使用

$logger = LoggerFactory::create('file');

$logger->log('系统启动');

2. 策略模式

interface PaymentStrategy {

    public function pay(float $amount): bool;

}



class AlipayStrategy implements PaymentStrategy {

    public function pay(float $amount): bool {

        echo "使用支付宝支付 {$amount} 元";

        return true;

    }

}



class PaymentContext {

    private PaymentStrategy $strategy;

    public function setStrategy(PaymentStrategy $strategy): void {

        $this->strategy = $strategy;

    }

    public function executePay(float $amount): bool {

        return $this->strategy->pay($amount);

    }

}



// 使用

$context = new PaymentContext();

$context->setStrategy(new AlipayStrategy());

$context->executePay(99.99);