feignを使用してhttpリクエスト解析エラーを送信

エラーは次のとおりです.

      
-----
[ChannelFeign#formRecog] ---> END HTTP (304117-byte body)
      
    
[ChannelFeign#formRecog] ] and content type [text/json;charset=UTF-8]] with root cause
org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [channel.domain.ChannelResponse] and content type [text/json;charset=UTF-8]
	at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:110) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.cloud.netflix.feign.support.SpringDecoder.decode(SpringDecoder.java:59) ~[spring-cloud-netflix-core-1.3.6.RELEASE.jar:1.3.6.RELEASE]
	at org.springframework.cloud.netflix.feign.support.ResponseEntityDecoder.decode(ResponseEntityDecoder.java:47) ~[spring-cloud-netflix-core-1.3.6.RELEASE.jar:1.3.6.RELEASE]
	at feign.SynchronousMethodHandler.decode(SynchronousMethodHandler.java:165) ~[feign-core-9.5.0.jar:?]
	at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:133) ~[feign-core-9.5.0.jar:?]
	at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:76) ~[feign-core-9.5.0.jar:?]
	at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103) ~[feign-core-9.5.0.jar:?]

org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [channel.domain.ChannelResponse] and content type [text/json;charset=UTF-8]
返されるタイプは[ChannelFeign#formRecog]content-type:text/jsonであることがわかります.charset=UTF-8
エラーの原因
インタフェースはJSON形式のデータを返すが、データを[text/json]として表すため、FeignはJSON解析器を用いて解析されず、応答データを対応するPOJOオブジェクトに変換できない.
ソース分析
Feignクライアント送信要求エントリ関数invoke()

    @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();
      }
      //     
      return dispatch.get(method).invoke(args);
    }

decode()は要求の復号関数を返す

  Object decode(Response response) throws Throwable {
    try {
      return decoder.decode(response, metadata.returnType());
    } catch (FeignException e) {
      throw e;
    } catch (RuntimeException e) {
      throw new DecodeException(e.getMessage(), e);
    }
  }

decodeに入ります.decode()、データの抽出

@Override
	@SuppressWarnings({"unchecked", "rawtypes", "resource"})
	public T extractData(ClientHttpResponse response) throws IOException {
		MessageBodyClientHttpResponseWrapper responseWrapper = new MessageBodyClientHttpResponseWrapper(response);
		if (!responseWrapper.hasMessageBody() || responseWrapper.hasEmptyMessageBody()) {
			return null;
		}
		MediaType contentType = getContentType(responseWrapper);

		for (HttpMessageConverter> messageConverter : this.messageConverters) {
			if (messageConverter instanceof GenericHttpMessageConverter) {
				GenericHttpMessageConverter> genericMessageConverter =
						(GenericHttpMessageConverter>) messageConverter;
				if (genericMessageConverter.canRead(this.responseType, null, contentType)) {
					if (logger.isDebugEnabled()) {
						logger.debug("Reading [" + this.responseType + "] as \"" +
								contentType + "\" using [" + messageConverter + "]");
					}
					return (T) genericMessageConverter.read(this.responseType, null, responseWrapper);
				}
			}
			if (this.responseClass != null) {
				if (messageConverter.canRead(this.responseClass, contentType)) {
					if (logger.isDebugEnabled()) {
						logger.debug("Reading [" + this.responseClass.getName() + "] as \"" +
								contentType + "\" using [" + messageConverter + "]");
					}
					return (T) messageConverter.read((Class) this.responseClass, responseWrapper);
				}
			}
		}

		throw new RestClientException("Could not extract response: no suitable HttpMessageConverter found " +
				"for response type [" + this.responseType + "] and content type [" + contentType + "]");
	}

GenericMessageConverterに入ります.canRead(this.responseType, null, contentType) 

	protected boolean canRead(MediaType mediaType) {
		if (mediaType == null) {
			return true;
		}
		for (MediaType supportedMediaType : getSupportedMediaTypes()) {
			if (supportedMediaType.includes(mediaType)) {
				return true;
			}
		}
		return false;
	}

ブレークポイントからmediaTypeがインタフェースから返されるcontent-type:text/jsonタイプであることが分かった.一方、supportedMediaTypeはアプリケーション/jsonなのでfalseに戻り、適切なコンバータが見つかりません. 
ソリューション1
Feignのデコーダの代わりにjson解析器に[text/plain]のデータを同時に解析させる

//                 [text/plain] 
public class WxMessageConverter extends MappingJackson2HttpMessageConverter {
    public WxMessageConverter(){
        List mediaTypes = new ArrayList<>();
        mediaTypes.add(MediaType.TEXT_PLAIN);
        setSupportedMediaTypes(mediaTypes);
    }
}

 

    Decoder Feign      
//          [text/plain]      json
@Bean
public Decoder feignDecoder(){
    WxMessageConverter wxConverter = new WxMessageConverter();
    ObjectFactory objectFactory = () -> new HttpMessageConverters(wxConverter);
    return new SpringDecoder(objectFactory);
}

参考:Buynow_Zhaoブログhttps://blog.csdn.net/a610786189/article/details/80508353?utm_source=copy
ソリューション2
返されるjson文字列にfastjosn変換を使用

        String result = channelFeign.formRecogTest(channelRequest);
        ChannelResponse hello = JSONObject.parseObject(result,
                new TypeReference>() {
                });

エラー2
リクエスト送信時にオブジェクト変換jsonは自動的にプロパティの頭文字を小文字にします
解決方法:

//@Data
public class ChannelRequest {
    //@JSONField(name="Header")
    @JsonProperty
    private ChannelReqHead Header;
    //@JSONField(name="Body")
    @JsonProperty
    private ChannelReqBody Body;
    
    //   get     JsonIgnore，jason    header    
    @JsonIgnore
    public ChannelReqHead getHeader() {
        return Header;
    }
    @JsonIgnore
    public void setHeader(ChannelReqHead header) {
        Header = header;
    }
    @JsonIgnore
    public ChannelReqBody getBody() {
        return Body;
    }
    @JsonIgnore
    public void setBody(ChannelReqBody body) {
        Body = body;
    }
    
}

jsonFieldを使っても機能しないので、
jsonIgnoreを使用しないと大文字と小文字が生成されます
例:{"Header":xxx,"header":xxx}