1.  添加拦截器

//在创建完成Feign.Builder对象后，添加一个拦截器到Feign.Builder中
//该拦截器可添加自定义请求参数，每次feign接口调用被触发时，都会经过该拦截器
class BeanPostProcessor implements BeanPostProcessor {

    private Logger logger = LoggerFactory.getLogger(this.getClass());

    @Autowired
    @Qualifier("com.xxx.RequestInterceptor")
    private RequestInterceptor requestInterceptor;

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        
        //判断当前对象是否为Feign.Builder
        if (bean instanceof Feign.Builder) {
            Feign.Builder feignBuilder = (Feign.Builder) bean;
            feignBuilder.requestInterceptor(this.requestInterceptor);
        }

        return bean;
    }
}

2. 拦截器

//feign 拦截器
class RequestInterceptor implements feign.RequestInterceptor {

        @Override
        public void apply(RequestTemplate template) {
            //在feign请求头中加入自定义参数
            template.header("key", "value");
        }
    }