springboot+策略模式+依赖注入

在Spring Boot中使用策略模式和依赖注入可以通过以下步骤实现：

1. 创建策略接口和多个实现类，例如：

public interface PaymentStrategy {
    void pay(double amount);
}

@Component
public class CreditCardPaymentStrategy implements PaymentStrategy {
    @Override
    public void pay(double amount) {
        System.out.println("Paid " + amount + " using credit card.");
    }
}

@Component
public class PayPalPaymentStrategy implements PaymentStrategy {
    @Override
    public void pay(double amount) {
        System.out.println("Paid " + amount + " using PayPal.");
    }
}

2. 创建一个策略工厂类，用于根据不同的条件返回不同的策略实现类，例如：

@Component
public class PaymentStrategyFactory {
    private final CreditCardPaymentStrategy creditCardPaymentStrategy;
    private final PayPalPaymentStrategy payPalPaymentStrategy;

    @Autowired
    public PaymentStrategyFactory(CreditCardPaymentStrategy creditCardPaymentStrategy, PayPalPaymentStrategy payPalPaymentStrategy) {
        this.creditCardPaymentStrategy = creditCardPaymentStrategy;
        this.payPalPaymentStrategy = payPalPaymentStrategy;
    }

    public PaymentStrategy getPaymentStrategy(String paymentMethod) {
        if ("creditCard".equalsIgnoreCase(paymentMethod)) {
            return creditCardPaymentStrategy;
        } else if ("payPal".equalsIgnoreCase(paymentMethod)) {
            return payPalPaymentStrategy;
        } else {
            throw new IllegalArgumentException("Invalid payment method: " + paymentMethod);
        }
    }
}

3. 在需要使用策略的地方，注入策略工厂，并根据条件获取对应的策略实现类，例如：

@RestController
public class PaymentController {
    private final PaymentStrategyFactory paymentStrategyFactory;

    @Autowired
    public PaymentController(PaymentStrategyFactory paymentStrategyFactory) {
        this.paymentStrategyFactory = paymentStrategyFactory;
    }

    @PostMapping("/pay")
    public void pay(@RequestParam String paymentMethod, @RequestParam double amount) {
        PaymentStrategy paymentStrategy = paymentStrategyFactory.getPaymentStrategy(paymentMethod);
        paymentStrategy.pay(amount);
    }
}

在上述代码中，我们使用了Spring Boot的依赖注入功能，将策略实现类注入到策略工厂中，并将策略工厂注入到控制器中。在控制器中，我们根据请求参数获取对应的策略实现类，并调用其方法完成支付操作。