在 Feign RequestInterceptor / RequestTemplate 中访问 URITemplate 或 RequestLine 值

Question

我正在针对具有硬 api 速率限制的云应用程序开发应用程序。为了让我的团队了解我们在这些限制方面有多接近，我想以一种有意义的方式统计从我们的应用发出的所有 API 调用。

我们使用 Feign 作为访问层，我希望能够使用 RequestInterceptor 来统计我们调用的不同 API 端点：

RequestInterceptor ri = rq -> addStatistics(rq.url());

现在这不起作用，因为生成的 URL 之后几乎总是计数为“1”，因为它们已经包含所有解析的路径变量，所以我得到计数​​

1 - /something/id1valueverycryptic/get
1 - /something/anothercrypticidkey/get

等等。

我希望以某种方式访问​​ @ResuqestLine 映射值 (GET /something/{id}/get) 或至少 uri 模板预解析 (/somethine/{id}/get)

有没有办法做到这一点？

谢谢！

Answer 1

也许您可以尝试使用自定义 feign InvocationHandlerFactory。

我已经设法使用如下代码记录 RequestInterceptor：

• 更改 EnableFeignClients 并添加 defaultConfiguration

  @EnableFeignClients(defaultConfiguration = FeignConfig.class)
  

• 添加默认的 feign 配置

  @Configuration
  public class FeignConfig {
  
  @Bean
  @ConditionalOnMissingBean
  public Retryer feignRetryer() {
      return Retryer.NEVER_RETRY;
  }
  
  @Bean
  @Scope("prototype")
  @ConditionalOnMissingBean
  public Feign.Builder feignBuilder(Retryer retryer) {
      return Feign.builder()
              .retryer(retryer)
              .invocationHandlerFactory((target, dispatch) -> new CountingFeignInvocationHandler(target, dispatch));
  }
  
  }
  

• 创建您的调用处理程序（基于 feign.ReflectiveFeign.FeignInvocationHandler 的代码）

  public class CountingFeignInvocationHandler implements InvocationHandler {
  
      private final Target target;
      private final Map<Method, MethodHandler> dispatch;
  
      public CountingFeignInvocationHandler(Target target, Map<Method, MethodHandler> dispatch) {
          this.target = checkNotNull(target, "target");
          this.dispatch = checkNotNull(dispatch, "dispatch for %s", target);
      }
  
      @Override
      public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
          if ("equals".equals(method.getName())) {
              try {
                  Object otherHandler =
                          args.length > 0 && args[0] != null ? Proxy.getInvocationHandler(args[0]) : null;
                  return equals(otherHandler);
              } catch (IllegalArgumentException e) {
                  return false;
              }
          } else if ("hashCode".equals(method.getName())) {
              return hashCode();
          } else if ("toString".equals(method.getName())) {
              return toString();
          }
  
          RequestLine requestLine = method.getAnnotation(RequestLine.class);
          addStatistics(requestLine.value());
  
          return dispatch.get(method).invoke(args);
      }
  
      @Override
      public boolean equals(Object obj) {
          if (obj instanceof CountingFeignInvocationHandler) {
              CountingFeignInvocationHandler other = (CountingFeignInvocationHandler) obj;
              return target.equals(other.target);
          }
          return false;
      }
  
      @Override
      public int hashCode() {
          return target.hashCode();
      }
  
      @Override
      public String toString() {
          return target.toString();
      }
  }
  

请小心检查您是否假装配置不是更复杂，在这种情况下根据需要扩展类。

Answer 2

    If you are using spring-cloud-starter-openfeign ,  You could do something like below 
    
    add the a primary contract bean 
    @Bean("YourContract")
    @Primary
        public Contract springpringContract() {
            return (targetType) -> {
    
                List<MethodMetadata> parseAndValidatateMetadata = new SpringMvcContract().parseAndValidatateMetadata(targetType);
                parseAndValidatateMetadata.forEach(metadata -> {
                    RequestTemplate template = metadata.template();
                    template.header("unresolved_uri", template.path().replace("{", "[").replace("}", "]"));
    
                });
                return parseAndValidatateMetadata;
            };
        }
    
    Add the contract to the feign client builder 
    @Bean
     public <T> T feignBuilder(Class<T> feignInterface, String targetURL) {
            return Feign.builder().client(getClient())
                    .contract(contract)
                    .
                    .
    }
    
    Once you are done with the above you should be able to access the unresolved path in the RequestTemplate

@component
public class FeignRequestFilter  implements RequestInterceptor {
    @Override
        public void apply(RequestTemplate template) {
            String unresolvedUri = template.headers().getOrDefault("unresolved_uri", Collections.singleton(template.path()))
                    .iterator().next();
    }
}