Spring 引导启动器 - RestTemplate

Question

我目前正在尝试编写 Spring 启动启动器，它将使用 API 网关自动验证我们的微服务，并将访问令牌包含在所有传出请求的标头中（朝向网关）。
我正在创建一个 RestTemplate bean 并为其提供我们的自定义拦截器，但我的问题是，通过这样做，我阻止其他团队（将使用此启动器）使用他们自己的 RestTemplate 配置，因为他们必须定义相同bean 导致多个 bean 存在。

@Bean
public RestTemplate restTemplate(){
  RestTemplate restTemplate = new RestTemplate();
  List<ClientHttpRequestInterceptor> interceptors = restTemplate.getInterceptors();
  if (interceptors.isEmpty()){
    interceptors = new ArrayList<>();
  }
  interceptors.add(clientCredentialsAuthInterceptor());
  restTemplate.setInterceptors(interceptors);
  return restTemplate;
}

是否有另一种方法可以拦截所有传出请求或使 RestTemplate 进一步可配置？

Answer 1

未经测试，但它可能会给你一个起点：

// Create an interface that users of your dependency 
// can implement which provides interceptors
public interface RestTemplateAuthInterceptorProvider {

  // This interface provides interceptors, so they can add as many as they want
  List<ClientHttpRequestInterceptor> provideInterceptor();
}

import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
// define a conditional default implementation of your interceptor provider
@Bean
@ConditionalOnMissingBean(RestTemplateAuthInterceptorProvider.class)
public RestTemplateAuthInterceptorProvider restTemplateAuthInterceptorProvider() {
  return () -> ... // implement your auth interceptor and return
}

// In your actual rest template creation use method argument injection
// If other teams implement the RestTemplateAuthInterceptorProvider interface
// conditional case above will be false and your implementation will not interfere
// If they dont implement RestTemplateAuthInterceptorProvider
// your default implementation will be here
@Bean
public RestTemplate restTemplate(RestTemplateAuthInterceptorProvider provider) {
  RestTemplate restTemplate = new RestTemplate();
  List<ClientHttpRequestInterceptor> interceptors = restTemplate.getInterceptors();
  if (interceptors == null){
    interceptors = new ArrayList<>();
  }
  interceptors.addAll(provider.provideInterceptor()); // from argument 
  restTemplate.setInterceptors(interceptors);
  return restTemplate;
}

编辑：另一种 hacky 方法是操作已经定义的 RestTemplate bean

@Component
@ConditionalOnBean(RestTemplate.class)
public class RestTemplateBeanCustomizer {

  private List<RestTemplate> restTemplateBeans;

  // This injects all restTemplate bean definitions to your bean as a list
  @Autowired
  public RestTemplateBeanCustomizer(List<RestTemplate> restTemplateBeans) {
    this.restTemplateBeans = restTemplateBeans;
  }

  @PostConstruct
  public void customizeRestTemplateBeans() {
      for (RestTemplate restTemplate : restTemplateBeans) {
        // Add your interceptors message handlers etc
        // restTemplate.set...
      }
  }
}