Feign call fails. JSON parse error illegal character ((ctrl-char, code 31)) only regular white space (R

background ：feign No call , Report errors , I've been sleepy for almost a month ！！！ Abominable , It took two days to solve , I tried Baidu once , It's no use , Almost crying , Now let's talk about the solution process .

① At first, I opened the log to further check the error information , Need to be in feign Use the log level in the configuration file , Log level is FULL, And add the log level in the configuration file .

② And then I found that there was a mistake 404 not found, At first, I thought that the parameters were not enough , Called as three parameters , Pass two parameters when calling , After adding it, it still reports an error , Then I found that the annotation was used incorrectly , It used to be @PathVariable（ Copied without change ）, Use @RequestParam Post error change （ A low-level mistake ）.

③ Report errors ：nested exception is com.fasterxml.jackson.core.JsonParseException: Illegal character ((CTRL-CHAR, code 31)): only regular white space ( , , ) is allowed between tokens
at [Source: (ByteArrayInputStream); line: 1, column: 2].

④ then feign Call interface , Use String receive , Print out the string , I found the code ？？？

It was also found that binary data came back ？？

Then began the crazy Baidu , I tried countless times , What configurations are added to various , You can't get rid of compression and so on , There is nothing like adding filters .

Finally, I found the answer in a big brother's article , Like me, he found garbled codes when he printed them , The question is gzip The received data is compressed , So random code , I still tried the useless configuration he said , The result is useful to me ！！！！！（ His next method that really works for her doesn't work for me , Also add interceptors ）

Online problem solving -feign Call error （Illegal character ((CTRL-CHAR, code 31)): only regular white space ( , , ) ）_im_ayday The blog of -CSDN Blog _feign Call error handling

answer ： Add... To the configuration file feign.compression.response.useGzipDecoder by true that will do .

⑤ The mess is gone , I found only Chinese garbled , by ！！！！！！ It's been a long time for me again , Baidu has tried all its schemes , I also saw feign Log all parameters , It seems no problem , People are almost crying , Finally found a solution .

@Configuration
public class FeignConfig implements RequestInterceptor {
    @Autowired
    private ObjectFactory<HttpMessageConverters> messageConverters;

    @Bean
    public Encoder feignFormEncoder() {
        return new SpringFormEncoder(new SpringEncoder(messageConverters));
    }

    @Bean
    public Decoder feignDecoder() {
        return new ResponseEntityDecoder(new SpringDecoder( () -> {
            FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter() {
                @Override
                public Object read(Type type, Class<?> contextClass, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
                    Object result=null;
                    if ("java.lang.String".equals(type.getTypeName())) {
                        result= StreamUtils.copyToString(inputMessage.getBody(), Charset.forName("utf8"));
                    } else {
                        result=super.read(type, contextClass, inputMessage);
                    }
                    return result;
                }
            };
            return new HttpMessageConverters(fastConverter);
        }));
    }

    @Override
    public void apply(RequestTemplate requestTemplate) {
        try {
            ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes) RequestContextHolder
                    .getRequestAttributes();
            if (null != servletRequestAttributes) {
                HttpServletRequest request = servletRequestAttributes.getRequest();
                //  Get all header file information key
                Enumeration<String> headerNames = request.getHeaderNames();
                if (null != headerNames) {
                    while (headerNames.hasMoreElements()) {
                        //  Get the header file key and value
                        String headerName = headerNames.nextElement();
                        String headerValue = request.getHeader(headerName);
                        //  skip content-length, Or you might report too many bites written problem 
                        if ("content-length".equalsIgnoreCase(headerName)) {
                            continue;
                        }
                        //  Add token data to header file , When used feign When called , Will be passed to the next microservice 
                        requestTemplate.header(headerName, headerValue);
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Bean
    public Logger.Level feignLoggerLevel() {
        return Logger.Level.FULL;
    }

}

Reference resources ：Feign The statement - You know

answer ： Add a decoder , Turn into utf8 That's all right. .