feign服务中调用，传递token feign服务中调用，传递token

默认spring-boot 微服务中用feign来做服务间调用，是不会携带token传递的。为了能让服务间调用的时候带上token，需要进行配置，增强resTemplate 1、先实现请求拦截器

/** * feign配置token */ @Configuration public class FeignRequestInterceptor implements RequestInterceptor {@Override public void apply(RequestTemplate requestTemplate) { // 这里可以添加feign请求的全局参数 ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes(); if (attributes == null || attributes.getRequest() == null) { return; } HttpServletRequest request = attributes.getRequest(); requestTemplate.header("token", request.getHeader("token")); requestTemplate.header("feignClient", "ifaas-hotel-robot-platform"); } }

2.在@FeignClient接口里添加configuration = {FeignConfig.class}

@FeignClient（name="被调用的服务名", configuration={FeignRequestInterceptor .class}）

由于feign的熔断器hystrix的隔离策略的原因，feign调用线程和主线程隔离了，请求上下文不共用，导致feign拦截器中 RequestContextHolder.getRequestAttributes(）为空原因：此属性指示HystrixCommand.run()执行哪种隔离策略，是以下两种选择之一：

THREAD —它在单独的线程上执行，并发请求受线程池中线程数的限制
SEMAPHORE —它在调用线程上执行，并发请求受信号量限制

3、解决feign中RequestContextHolder.getRequestAttributes(）为null方案有两种： 3.1、修改隔离策略：默认是采用THREAD ，修改成SEMAPHORE 即可，但是不推荐这种做法，因为并发请求收到限制。
3.2、自定义feign的并发策略继承HystrixConcurrencyStrategy，然后重写wrapCallable方法。如下：

import com.netflix.hystrix.strategy.HystrixPlugins; import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy; import lombok.extern.slf4j.Slf4j; import org.springframework.context.annotation.Primary; import org.springframework.stereotype.Component; import org.springframework.web.context.request.RequestAttributes; import org.springframework.web.context.request.RequestContextHolder; import java.util.concurrent.Callable; /** * Created by YangGuanRong * date: 2022/3/8 */ @Slf4j @Primary @Component public class CustomFeignHystrixConcurrencyStrategy extends HystrixConcurrencyStrategy {public CustomFeignHystrixConcurrencyStrategy() { try {HystrixPlugins.getInstance().registerConcurrencyStrategy(this); } catch (Exception e) { log.error("Failed to register Sleuth Hystrix Concurrency Strategy", e); } }@Override public Callable wrapCallable(Callable callable) { RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes(); return new WrappedCallable<>(callable, requestAttributes); }static class WrappedCallable implements Callable { private final Callable target; private final RequestAttributes requestAttributes; public WrappedCallable(Callable target, RequestAttributes requestAttributes) { this.target = target; this.requestAttributes = requestAttributes; }/** * feign opens the fuse (hystrix): feign.hystrix.enabled=ture, and uses the default signal isolation level, * The HttpServletRequest object is independent of each other in the parent thread and the child thread and is not shared. * So the HttpServletRequest data of the parent thread used in the child thread is null, * naturally it is impossible to obtain the token information of the request header In a multithreaded environment, call before the request, set the context before the call * * feign启用了hystrix，并且feign.hystrix.enabled=ture。采用了线程隔离策略。 * HttpServletRequest 请求在对象在父线程和子线程中相互独立，且不共享 * 所以父线程的 HttpServletRequest 在子线程中为空， * 所以通常在多线程环境中，在请求调用之前设置上下文 * @return T * @throws Exception Exception */ @Override public T call() throws Exception { try { // Set true to share the parent thread's HttpServletRequest object setting RequestContextHolder.setRequestAttributes(requestAttributes, true); return target.call(); } finally { RequestContextHolder.resetRequestAttributes(); } } } }

【feign服务中调用，传递token】