<em>Mac</em>Book项目 2009年学校开始实施<em>Mac</em>Book项目,所有师生配备一本<em>Mac</em>Book,并同步更新了校园无线网络。学校每周进行电脑技术更新,每月发送技术支持资料,极大改变了教学及学习方式。因此2011
2021-06-01 09:32:01
傳送請求開始
----- [ChannelFeign#formRecog] ---> END HTTP (304117-byte body)
傳送請求結束
返回開始
[ChannelFeign#formRecog] <--- HTTP/1.1 200 OK (4948ms) [ChannelFeign#formRecog] content-length: 5207 [ChannelFeign#formRecog] content-type: text/json;charset=UTF-8 [ChannelFeign#formRecog] date: Mon, 08 Oct 2018 10:47:03 GMT [ChannelFeign#formRecog] x-vcap-request-id: c323f65a-12e6-4604-7393-a4bf0ca403d5 [ChannelFeign#formRecog] [ChannelFeign#formRecog] {json格式的資料} [ChannelFeign#formRecog] <--- END HTTP (5207-byte body)
返回結束
ERROR org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is feign.codec.DecodeException: Could not extract response: no suitable HttpMessageConverter found for response type [channel.domain.ChannelResponse<TableData>] 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<TableData>] 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<TableData>] and content type [text/json;charset=UTF-8]
可以看到返回的型別為[ChannelFeign#formRecog] content-type: text/json;charset=UTF-8
介面返回為JSON格式資料但卻將資料表示為了[text/json]導致Feign沒有采用JSON解析器來解析,從而無法將響應資料轉化為對應的POJO物件;
原始碼分析
feign使用者端傳送請求入口函數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(); } // 分發請求 return dispatch.get(method).invoke(args); }
decode()返回請求的解碼函數
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); } }
進入decode.decode(),提取資料
@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 + "]"); }
進入genericMessageConverter.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; }
通過斷點發現mediaType為介面返回的content-type:text/json型別。而supportedMediaType為application/json,所以返回false,找不到合適的轉換器。
替代Feign的解碼器,使json解析器同時解析[text/plain]的資料
// 建立一個新的轉換器 解析微信的 [text/plain] public class WxMessageConverter extends MappingJackson2HttpMessageConverter { public WxMessageConverter(){ List<MediaType> mediaTypes = new ArrayList<>(); mediaTypes.add(MediaType.TEXT_PLAIN); setSupportedMediaTypes(mediaTypes); } }
注入新的Decoder Feign將自動 替換
// 解決微信返回引數為[text/plain] 無法轉化為json @Bean public Decoder feignDecoder(){ WxMessageConverter wxConverter = new WxMessageConverter(); ObjectFactory<HttpMessageConverters> objectFactory = () -> new HttpMessageConverters(wxConverter); return new SpringDecoder(objectFactory); }
對返回的json字串使用fastjosn轉換
String result = channelFeign.formRecogTest(channelRequest); ChannelResponse<TableData> hello = JSONObject.parseObject(result, new TypeReference<ChannelResponse<TableData>>() { });
傳送請求時物件轉換json會自動將屬性的首字母小寫
解決方法:
//@Data public class ChannelRequest { //@JSONField(name="Header") @JsonProperty private ChannelReqHead Header; //@JSONField(name="Body") @JsonProperty private ChannelReqBody Body; // 如果get方法上不加JsonIgnore,jason化時小寫header也會出現 @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; } }
使用jsonField不起作用,不使用jsonIgnore會生成大寫和小寫
如:{“Header”:xxx,"header":xxx}
以上為個人經驗,希望能給大家一個參考,也希望大家多多支援it145.com。
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