问题

当我们使用Feign去调其它微服务时，如果我们使用的shiro或者其它需要通过Cookie或者Session来实现鉴权的，可能会出现Feign丢失Session的问题。Feign默认不会带请求头访问

解决方案

实现RequestInterceptor接口，并重写apply方法以实现header转发

@Configuration
public class FeignConfig implements RequestInterceptor {

    @Bean
    public Retryer feignRetryer() {
        return new Retryer.Default(100, SECONDS.toMillis(1), 5);
    }

    @Override
    public void apply(RequestTemplate requestTemplate) {

        RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
        if (requestAttributes == null) {
            return;
        }

        HttpServletRequest request = ((ServletRequestAttributes) requestAttributes).getRequest();
        Enumeration<String> headerNames = request.getHeaderNames();
        if (headerNames != null) {
            while (headerNames.hasMoreElements()) {
                String name = headerNames.nextElement();
                Enumeration<String> values = request.getHeaders(name);
                while (values.hasMoreElements()) {
                    String value = values.nextElement();
                    requestTemplate.header(name, value);
                }
            }
        }

    }
}