Spring Cloud之Finchley版学习（十四）-Feign使用Hystrix

Feign默认已经整合了Hystrix，本节详细探讨Feign使用Hystrix的具体细节。

服务降级

• 加配置，默认Feign是不启用Hystrix的，需要添加如下配置启用Hystrix，这样所有的Feign Client都会受到Hystrix保护！
  

  feign:
    hystrix:
      enabled: true

• 提供Fallback：
  

  @FeignClient(name = "microservice-provider-user", fallback = UserFeignClientFallback.class)
  public interface UserFeignClient {
    @GetMapping("/users/{id}")
    User findById(@PathVariable("id") Long id);
  }
  
  @Component
  class UserFeignClientFallback implements UserFeignClient {
    @Override
    public User findById(Long id) {
      return new User(id, "默认用户", "默认用户", 0, new BigDecimal(1));
    }
  }

获得造成fallback的原因

@FeignClient(name = "microservice-provider-user", fallbackFactory = UserFeignClientFallbackFactory.class)
public interface UserFeignClient {
  @GetMapping("/users/{id}")
  User findById(@PathVariable("id") Long id);
}

@Component
@Slf4j
class UserFeignClientFallbackFactory implements FallbackFactory<UserFeignClient> {
  @Override
  public UserFeignClient create(Throwable throwable) {
    return new UserFeignClient() {
      @Override
      public User findById(Long id) {
        log.error("进入回退逻辑", throwable);
        return new User(id, "默认用户", "默认用户", 0, new BigDecimal(1));
      }
    };
  }
}

Feign启用/禁用Hystrix

全局启用

feign.hystrix.enabled: true

全局禁用

feign.hystrix.enabled: false

或直接省略不写。

局部启用

利用Feign配置的自定义，为指定Feign Client指定如下配置类即可，Feign配置自定义详见：跟我学Spring Cloud（Finchley版）-10-Feign深入

public class FeignDisableHystrixConfiguration {
    @Bean
	@Scope("prototype")
	public HystrixFeign.Builder feignBuilder() {
		return HystrixFeign.builder();
	}
}

局部禁用

public class FeignDisableHystrixConfiguration {
    @Bean
	@Scope("prototype")
	public Feign.Builder feignBuilder() {
		return Feign.builder();
	}
}