摘要：public interface PaymentService { void pay(double amount);}@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Qualifierp
还在用冗长的if-else或switch语句管理多个服务实现？
相信不少Spring Boot开发者都遇到过这样的场景：需要根据不同条件动态选择不同的服务实现。
如果告诉你可以完全摆脱条件判断，让Spring自动选择合适的实现——只需要一个注解，你是否感兴趣？
本文将详细介绍这种优雅的实现方式。
if (paymentType.equals("Paypal")) { return new PaypalPaymentService;} else if (paymentType.equals("Stripe")) { return new StripePaymentService;}❌ 这种写法存在明显问题：代码冗余、难以维护、扩展性差。
接下来看看如何优化。
最近我们翻译了Spring Boot和Spring AI的中文文档：
Spring Boot 3.4：https://doc.spring4all.com/spring-boot/3.4.6/
Spring Boot 3.5：https://doc.spring4all.com/spring-boot/3.5.0/
Spring AI 1.0.0：https://doc.spring4all.com/spring-ai/reference/
public interface PaymentService { void pay(double amount);}@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Qualifierpublic @interface PaymentType { String value;}@PaymentType("PAYPAL")@Servicepublic class PaypalPaymentService implements PaymentService { public void pay(double amount) { System.out.println("使用PayPal支付：$" + amount); }}@PaymentType("Stripe")@Servicepublic class StripePaymentService implements PaymentService { public void pay(double amount) { System.out.println("使用Stripe支付：$" + amount); }}@Componentpublic class PaymentServiceFactory { private final Map serviceMap = new HashMap; @Autowired public PaymentServiceFactory(List services) { for (PaymentService service : services) { PaymentType Annotation = service.getClass.getAnnotation(PaymentType.class); if (annotation != null) { serviceMap.put(annotation.value, service); } } } public PaymentService getService(String type) { return serviceMap.get(type); }}@RestControllerpublic class PaymentController { private final PaymentServiceFactory paymentServiceFactory; @Autowired public PaymentController(PaymentServiceFactory paymentServiceFactory) { this.paymentServiceFactory = paymentServiceFactory; } @PostMapping("/pay") public String makePayment(@RequestParam String method, @RequestParam double amount) { PaymentService service = paymentServiceFactory.getService(method.toUpperCase); if (service == null) { return "暂不支持该支付方式"; } service.pay(amount); return "支付成功"; }}将@PaymentType与@Profile("prod")结合使用，Spring会根据当前激活的配置文件自动选择对应的实现。
来源：码农看看
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