The dependencies of some of the beans in the application context form a cycle:

Error

• rest template을 다음과 같이 사용했을 때 Error가 발생했다.
• service 인터페이스

  package kr.pe.playdata.service;
  
  import java.util.concurrent.CompletableFuture;
  
  public interface RecommandService {
      /*
          관광지 추천 서비스 인터페이스
       */
  
      public CompletableFuture<String> recommand(String keywords);
  }

• service 구현

  package kr.pe.playdata.service.impl;
  
  import kr.pe.playdata.service.RecommandService;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.scheduling.annotation.Async;
  import org.springframework.stereotype.Service;
  import org.springframework.util.LinkedMultiValueMap;
  import org.springframework.util.MultiValueMap;
  import org.springframework.web.client.RestTemplate;
  import java.util.concurrent.CompletableFuture;
  
  @Service
  public class RecommandServiceImpl implements RecommandService {
      /*
          관광지를 추천해주는 서비스 구현체
       */
  
      @Autowired
      private RestTemplate restTemplate;
  
  		@Bean
      public RestTemplate restTemplate(){
          return new RestTemplate();
      }
  
      @Async("asyncExecutor")
      public CompletableFuture<String> recommand(String keywords){
          String url = "http://127.0.0.1:5000/recommand";
          MultiValueMap<String, String> param = new LinkedMultiValueMap<String, String>();
          param.add("keywords",keywords);
          String sb = restTemplate.postForObject(url, param, String.class);
          return CompletableFuture.completedFuture(sb);
      }
  }

• Error 발생
  

Error 해결

• RestTemplate Config를 만들어 RestTemplate을 미리 Bean에 등록하였다.

  package kr.pe.playdata.config;
  
  import org.springframework.context.annotation.Bean;
  import org.springframework.context.annotation.Configuration;
  import org.springframework.web.client.RestTemplate;
  
  @Configuration
  public class RestTemplateConfig {
      /*
          rest Config
       */
  
      @Bean
      public RestTemplate restTemplate(){
          return new RestTemplate();
      }
  }

참고 사이트

Circular Dependency in Spring Boot