Dynamic Payment Processor Selection in Laravel Using the Factory Pattern

在之前的文章中，我们探索了 Laravel 中处理付款处理的两种不同方法：

• 硬编码服务绑定
• 上下文绑定。

虽然这两种方法都很有效，但在根据运行时条件（例如用户输入、配置设置）动态选择支付处理器时它们都有其局限性。

在第三部分也是最后一部分中，我们将研究一种更灵活的方法：使用工厂模式。这种设计模式允许我们根据上下文选择适当的 PaymentProcessorInterface 实现（例如，根据请求在 Stripe 或 PayPal 之间进行选择）。

实施工厂模式

工厂模式提供了一个可扩展的解决方案，可以在运行时动态解析不同的实现。以下是逐步设置的方法。

第1步：创建工厂接口

首先，让我们定义一个 PaymentProcessorFactoryInterface，它概述了如何解析不同的支付处理器。

<?php namespace App\Contracts;

interface PaymentProcessorFactoryInterface
{
    public function getProcessor(string $provider): PaymentProcessorInterface;
}

此接口确保我们创建的任何工厂都将具有 getProcessor 方法，负责根据提供的参数（例如“stripe”或“paypal”）返回适当的支付处理器。

第 2 步：创建工厂实现

接下来，我们将实现工厂，根据提供商的输入解析适当的支付处理器。

<?php namespace App\Services;

use App\Contracts\PaymentProcessorInterface;
use App\Contracts\PaymentProcessorFactoryInterface;
use App\Services\StripePaymentProcessor;
use App\Services\PayPalPaymentProcessor;

class PaymentProcessorFactory implements PaymentProcessorFactoryInterface
{
    public function getProcessor(string $provider): PaymentProcessorInterface
    {
        switch ($provider) {
            case 'stripe':
                return new StripePaymentProcessor(); // Can be resolved via the container if needed
            case 'paypal':
                return new PayPalPaymentProcessor(); // Can also be resolved via the container
            default:
                throw new \Exception("Unsupported payment provider: $provider");
        }
    }
}

该工厂根据运行时提供的输入动态选择正确的支付处理器。在此示例中，我们直接返回 StripePaymentProcessor 和 PayPalPaymentProcessor 的新实例。如果需要，这些类也可以从 Laravel 的服务容器中解析，以便更好的管理。

第 3 步：实施 Stripe 和 PayPal 处理器

确保您拥有实现 PaymentProcessorInterface 的 StripePaymentProcessor 和 PayPalPaymentProcessor 类。

示例：StripePaymentProcessor

<?php namespace App\Services;

use App\Contracts\PaymentProcessorInterface;

class StripePaymentProcessor implements PaymentProcessorInterface
{
    public function createPayment(float $amount, string $currency, array $paymentDetails): array
    {
        // Stripe-specific implementation
    }

    public function processPayment(array $paymentData): array
    {
        // Stripe-specific implementation
    }

    public function refundPayment(string $transactionId, float $amount): bool
    {
        // Stripe-specific implementation
    }
}

示例：PayPalPaymentProcessor

类似地，实现 PayPalPaymentProcessor 类，遵循与 StripePaymentProcessor 相同的模式。

第四步：在服务容器中绑定工厂

为了确保工厂在整个 Laravel 应用程序中可用，您需要将 PaymentProcessorFactory 绑定到 Laravel 的服务容器。您可以在 AppServiceProvider 中执行此操作。

在AppProvidersAppServiceProvider.php中，在register方法中添加以下内容：

public function register()
{
    $this->app->singleton(\App\Contracts\PaymentProcessorFactoryInterface::class, \App\Services\PaymentProcessorFactory::class);
}

此绑定告诉 Laravel 在请求 PaymentProcessorFactoryInterface 时使用 PaymentProcessorFactory，确保整个应用程序中只有一个工厂实例。

第 5 步：在控制器中使用工厂

现在工厂已经设置完毕，您可以将其注入控制器中，以根据运行时数据（例如请求输入）动态选择适当的支付处理器。

示例：PaymentController

<?php namespace App\Http\Controllers;

use App\Contracts\PaymentProcessorFactoryInterface;
use Illuminate\Http\Request;

class PaymentController extends Controller
{
    protected $paymentProcessorFactory;

    public function __construct(PaymentProcessorFactoryInterface $paymentProcessorFactory)
    {
        $this->paymentProcessorFactory = $paymentProcessorFactory;
    }

    public function makePayment(Request $request)
    {
        $provider = $request->input('provider'); // E.g., 'stripe' or 'paypal'
        $amount = $request->input('amount');
        $currency = $request->input('currency');
        $paymentDetails = $request->input('details');

        // Get the appropriate payment processor based on the provider
        $paymentProcessor = $this->paymentProcessorFactory->getProcessor($provider);

        // Use the selected payment processor to create a payment
        $response = $paymentProcessor->createPayment($amount, $currency, $paymentDetails);

        return response()->json($response);
    }
}

在此控制器中，我们通过依赖注入注入 PaymentProcessorFactoryInterface。当请求付款时，我们根据请求确定付款提供商（例如 Stripe 或 PayPal），将其传递给工厂，并动态解析适当的付款处理器。

第 6 步：处理不同的支付提供商

在此设置中，控制器现在可以通过简单地切换请求中的提供商名称来动态处理不同的支付提供商。当您需要处理多个支付网关而无需重复逻辑或将代码与特定实现紧密耦合时，此方法特别强大。

结论

在 Laravel 11 中使用工厂模式提供了一种高度灵活的方法来在运行时选择不同的支付处理器。以下是我们所涉及步骤的摘要：

• Factory Interface and Implementation: Created a factory that dynamically resolves the correct payment processor based on a string input.
• Processor Implementations: Ensured that both StripePaymentProcessor and PayPalPaymentProcessor classes implement PaymentProcessorInterface.
• Service Container Binding: Bound the factory in the service container to allow easy injection throughout the application. Dynamic Selection in Controllers: Used the factory inside a controller to dynamically select and use the appropriate payment processor based on runtime data.

Software Design Principles and Design Patterns

We started this 3 parts tutorial using a single payment processor, with a hardcoded selection, then we were using an in code("compile time") configuration by using Laravel Service Container Binding, then in this part we kept refactoring with design principles and design patterns in mind, which allowed us to refactor the code, achieving:

• Dynamic Flexibility: The Factory Pattern allows for the selection of different payment processors at runtime, making your application more flexible and scalable.
• Loose Coupling: By injecting the factory, your controllers are loosely coupled to the payment processors, making it easier to add or replace payment gateways in the future.
• Maintainability: This approach provides a cleaner and more maintainable codebase, especially when dealing with multiple payment options.

With this setup, we now have a powerful, flexible system for handling payments in Laravel. If we need to support additional processors, we can easily extend the factory to support and modify the logic for selecting providers, and handle different business logic scenarios.

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