eureka+zuul+ribbon体系中的自定义调用链demo

    // 在zuul转发或者feign调用前写入动态路由策略,指定转发到有该tag-value的服务 
    RibbonFilterContextHolder.getCurrentContext()
            .add("${tagName}", ${tagValue});
    
    // 客户端服务配置
    eureka:
      instance:
        metadata-map:
          tagName1: tagValue1
          tagName2: tagValue2

public abstract class ServiceLancherHandler {
    protected boolean handle(String serviceId) {
        String serviceLancher = getServiceLancher(serviceId);
        if (StringUtils.isEmpty(serviceLancher)){
            return false;
        }
        RibbonFilterContextHolder.clearCurrentContext();
        RibbonFilterContextHolder.getCurrentContext()
                .add("lancher", serviceLancher);
        return true;
    }
    /**
        子类通过实现该方法可自定义访问策略
    */
    abstract String getServiceLancher(String serviceId);
}

    // 配置指定tag的职责链,
    // 例如可定义先从header中寻找,
    // 再从redis中寻找,再从数据库中寻找,
    //可自行实现ServiceLancherHandler,本demo只实现了从header中寻找
	@Bean
	ServiceLancherHandlerChain serviceLancherHandlerChain(){
		ServiceLancherHandlerChain chain = new ServiceLancherHandlerChain();
		chain.addHandler(new RequestHeaderServiceLancherHandler());
		return chain;
	}
	
	// AbFilter extends ZuulFilter
	// 继承zuulfilter,实现自定义zuul前置拦截器,在服务转发前指定路由策略
	// 在自定义的zuulfilter中,获取到第一层转发服务id后,调用指定tag的职责链方法
    public Object run() throws ZuulException {
        String serviceId = getServiceId();
        if(StringUtils.isBlank(serviceId)){
            return null;
        }
        serviceLancherHandlerChain.handle(serviceId);
        return null;
    }

    FeignRibbonFilterInterceptor.class
    // 拦截 FeignClient 在feign远程调用前指定调用指定tag的职责链方法,调用后清除
    @Pointcut("@within(org.springframework.cloud.openfeign.FeignClient)")
    // PS 需实现 RequestInterceptor,将需要的requestHead在feign进行服务间调用时转发到下一级服务,否则服务间调用将损失前端过来的header
    FeignHeadersInterceptor.class
    ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
    HttpServletRequest request = servletRequestAttributes.getRequest();
    Map<String, String> headers = HeaderUtil.getHeaders(request);
    if (headers!=null && headers.size() > 0) {
        Iterator<Entry<String, String>> iterator = headers.entrySet().iterator();
        while (iterator.hasNext()) {
            Entry<String, String> entry = iterator.next();
            template.header(entry.getKey(), entry.getValue());
        }
    }
    // 可根据实际业务需求对转发的header进行增减