1. 问题起因

• 需要将业务数据放入HttpServletRequest的请求头里面。
• 被调用的模块，rest接口设计是以HttpServletRequest作为 参数的。
• 于是夫，秉信feign的接口设计必须和提供者参数一样。
• 消费者调用feign接口，报一堆奇奇怪怪的错误。报错Jackson中的错误…

2. 问题分析

1. feign接口是不支持HttpServletRequest作为参数的
2. feign和hystrix整合开启了feign对hystrix的熔断，导致feign的拦截器获取不到请求

3. 问题解决

• 问题1解决, 使用feign的拦截器，将请求拦截下

  package top.bitqian.config;import feign.RequestInterceptor;
  import feign.RequestTemplate;
  import org.springframework.context.annotation.Configuration;
  import org.springframework.web.context.request.RequestContextHolder;
  import org.springframework.web.context.request.ServletRequestAttributes;import javax.servlet.http.HttpServletRequest;
  import java.util.Enumeration;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import java.util.Objects;/*** @author echo lovely* @date 2021/2/1 20:45*/
  @Configuration
  public class FeignConfig implements RequestInterceptor {/*** 复写feign请求对象* @param requestTemplate hhh*/@Overridepublic void apply(RequestTemplate requestTemplate) {//获取请求头Map<String,String> headers = getHeaders(Objects.requireNonNull(getHttpServletRequest()));for(String headerName : headers.keySet()){requestTemplate.header(headerName, getHeaders(getHttpServletRequest()).get(headerName));}}//获取请求对象private HttpServletRequest getHttpServletRequest() {try {return ((ServletRequestAttributes) Objects.requireNonNull(RequestContextHolder.getRequestAttributes())).getRequest();} catch (Exception e) {e.printStackTrace();return null;}}//拿到请求头信息private Map<String, String> getHeaders(HttpServletRequest request) {Map<String, String> map = new LinkedHashMap<>();Enumeration<String> enumeration = request.getHeaderNames();while (enumeration.hasMoreElements()) {String key = enumeration.nextElement();String value = request.getHeader(key);map.put(key, value);}return map;}}

这样feign接口中，就不用写HttpServletRequest 请求了，请求会通过feign发送到提供者。

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• 问题二解决：造成原因，feing.hystrix.enabled=true， 开启了熔断

• 解决，将上面配置更换为：

  hystrix:command:default:execution:isolation:strategy: SEMAPHORE
  

参考：
https://www.jianshu.com/p/3b34234c4623

https://blog.csdn.net/cgd_8523/article/details/100575915

https://blog.csdn.net/liu_ares/article/details/100371441