使用feign发送http请求解析报错的问题

错误如下

发送请求开始

-----[channelfeign#formrecog] ---> end http (304117-byte body)

发送请求结束

返回开始

[channelfeign#formrecog] <--- http/1.1 200 ok (4948ms)[channelfeign#formrecog] content-length: 5207[channelfeign#formrecog] content-type: text/json;chart=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格式的数据}[channelfeign#formrecog] <--- end http (5207-byte body)

返回结束

error org.apache.catalina.core.containerba.[tomcat].[localhost].[/].[dispatcherrvlet] : rvlet.rvice() for rvlet [dispatcherrvlet] in context with path [] threw exception [request processing failed; nested exception is feign.codec.decodeexception: could not extract respon: no suitable httpmessageconverter found for respon type [channel.domain.channelrespon<tabledata>] and content type [text/json;chart=utf-紫鸭拓草8]] with root cau
org.springframework.web.client.restclientexception: could not extract respon: no suitable httpmessageconverter found for respon type [channel.domain.channelrespon<tabledata>] and content type [text/json;chart=utf-8]
at org.springframework.web.client.httpmessageconverterextractor.extractdata(httpmessageconverterextractor.java:110) ~[spring-web-4.3.13.relea.jar:4.3.13.relea]
at org.springframework.cloud.netflix.feign.support.springdecoder.decode(springdecoder.java:59) ~[spring-cloud-netflix-core-1.3.6.relea.jar:1.3.6.relea]
at org.springframework.cloud.netflix.feign.support.responentitydecoder.decode(responentitydecoder.java:47) ~[spring-cloud-netflix-core-1.3.6.relea.jar:1.3.6.relea]
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(synchronousmethod负荆请罪的历史人物是谁handler.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 respon: no suitable httpmessageconverter found for respon type [channel.domain.channelrespon<tabledata>] and content type [text/json;chart=utf-8]

可以看到返回的类型为[channelfeign#formrecog] content-type: text/json;chart=utf-8

错误原因

接口返回为json格式数据但却将数据表示为了[text/json]导致feign没有采用json解析器来解析，从而无法将响应数据转化为对应的pojo对象；

源码分析

feign客户端发送请求入口函数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 fal;    }   } el if ("hashcode".equals(method.getname())) {    return hashcode();   } el if ("tostring".equals(method.getname())) {    return tostring();   }   // 分发请求   return dispatch.get(method).invoke(args);  }

decode()返回请求的解码函数

 object decode(respon respon) throws throwable {  try {   return decoder.decode(respon, metadata.re密松电站turntype());  } catch (feignexception e) {   throw e;  } catch (runtimeexception e) {   throw new decodeexception(e.getmessage(), e);  } }

进入decode.decode()，提取数据

@override @suppresswarnings({"unchecked", "rawtypes", "resource"}) public t extractdata(clienthttprespon respon) throws ioexception {  messagebodyclienthttpresponwrapper responwrap师说特殊句式per = new messagebodyclienthttpresponwrapper(respon);  if (!responwrapper.hasmessagebody() || responwrapper.hamptymessagebody()) {   return null;  }  mediatype contenttype = getcontenttype(responwrapper);  for (httpmessageconverter<?> messageconverter : this.messageconverters) {   if (messageconverter instanceof generichttpmessageconverter) {    generichttpmessageconverter<?> genericmessageconverter =      (generichttpmessageconverter<?>) messageconverter;    if (genericmessageconverter.canread(this.respontype, null, contenttype)) {     if (logger.isdebugenabled()) {      logger.debug("reading [" + this.respontype + "] as \"" +        contenttype + "\" using [" + messageconverter + "]");     }     return (t) genericmessageconverter.read(this.respontype, null, responwrapper);    }   }   if (this.responclass != nu中国新歌声 冠军ll) {    if (messageconverter.canread(this.responclass, contenttype)) {     if (logger.isdebugenabled()) {      logger.debug("reading [" + this.responclass.getname() + "] as \"" +        contenttype + "\" using [" + messageconverter + "]");     }     return (t) messageconverter.read((class) this.responclass, responwrapper);    }   }  }  throw new restclientexception("could not extract respon: no suitable httpmessageconverter found " +    "for respon type [" + this.respontype + "] and content type [" + contenttype + "]"); }

进入genericmessageconverter.canread(this.respontype, null, contenttype)

 protected boolean canread(mediatype mediatype) {  if (mediatype == null) {   return true;  }  for (mediatype supportedmediatype : getsupportedmediatypes()) {   if (supportedmediatype.includes(mediatype)) {    return true;   }  }  return fal; }

通过断点发现mediatype为接口返回的content-type：text/json类型。而supportedmediatype为application/json，所以返回fal，找不到合适的转换器。

解决方案一

替代feign的解码器，使json解析器同时解析[text/plain]的数据

// 创建一个新的转换器 解析微信的 [text/plain]public class wxmessageconverter extends mappingjackson2httpmessageconverter {  public wxmessageconverter(){    list<mediatype> mediatypes = new arraylist<>();    mediatypes.add(mediatype.text_plain);    tsupportedmediatypes(mediatypes);  }}

注入新的decoder feign将自动 替换

// 解决微信返回参数为[text/plain] 无法转化为json@beanpublic decoder feigndecoder(){  wxmessageconverter wxconverter = new wxmessageconverter();  objectfactory<httpmessageconverters> objectfactory = () -> new httpmessageconverters(wxconverter);  return new springdecoder(objectfactory);}

解决方案二

对返回的json字符串使用fastjosn转换

    string result = channelfeign.formrecogtest(channelrequest);    channelrespon<tabledata> hello = jsonobject.parobject(result,        new typereference<channelrespon<tabledata>>() {        });

错误2

发送请求时对象转换json会自动将属性的首字母小写

解决方法：

//@datapublic 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化时小写header也会出现  @jsonignore  public channelreqhead getheader() {    return header;  }  @jsonignore  public void theader(channelreqhead header) {    header = header;  }  @jsonignore  public channelreqbody getbody() {    return body;  }  @jsonignore  public void tbody(channelreqbody body) {    body = body;  } }

使用jsonfield不起作用，

不使用jsonignore会生成大写和小写

如：{“header”:xxx,”header”:xxx}

以上为个人经验，希望能给大家一个参考，也希望大家多多支持www.887551.com。