Spring Cloud Gateway实现灰度发布方案

　　@Slf4j

　　@Component

　　public class GrayReactiveLoadBalancerClientFilter implements GlobalFilter, Ordered {

　　private static final int LOAD_BALANCER_CLIENT_FILTER_ORDER = 10150;

　　private final LoadBalancerClientFactory clientFactory;

　　public GrayReactiveLoadBalancerClientFilter(LoadBalancerClientFactory clientFactory) {

　　this.clientFactory = clientFactory;

　　}

　　@Override

　　public Mono filter(ServerWebExchange exchange, GatewayFilterChain chain) {

　　URI url = (URI) exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);

　　String schemePrefix = (String) exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR);

　　if (url != null && ("grayLb".equals(url.getScheme()) || "grayLb".equals(schemePrefix))) {

　　ServerWebExchangeUtils.addOriginalRequestUrl(exchange, url);

　　if (log.isTraceEnabled()) {

　　log.trace(ReactiveLoadBalancerClientFilter.class.getSimpleName() + " url before: " + url);

　　}

　　return this.choose(exchange).doOnNext((response) -> {

　　if (!response.hasServer()) {

　　throw NotFoundException.create(true, "Unable to find instance for " + url.getHost());

　　} else {

　　URI uri = exchange.getRequest().getURI();

　　String overrideScheme = null;

　　if (schemePrefix != null) {

　　overrideScheme = url.getScheme();

　　}

　　DelegatingServiceInstance serviceInstance = new DelegatingServiceInstance((ServiceInstance) response.getServer(), overrideScheme);

　　URI requestUrl = this.reconstructURI(serviceInstance, uri);

　　if (log.isTraceEnabled()) {

　　log.trace("LoadBalancerClientFilter url chosen: " + requestUrl);

　　}

　　exchange.getAttributes().put(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR, requestUrl);

　　}

　　}).then(chain.filter(exchange));

　　} else {

　　return chain.filter(exchange);

　　}

　　}

　　private Mono> choose(ServerWebExchange exchange) {

　　URI uri = (URI) exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);

　　GrayRoundRobinLoadBalancer loadBalancer = new GrayRoundRobinLoadBalancer(clientFactory.getLazyProvider(uri.getHost(), ServiceInstanceListSupplier.class), uri.getHost());

　　return loadBalancer.choose(this.createRequest(exchange));

　　}

　　private Request createRequest(ServerWebExchange exchange) {

　　HttpHeaders headers = exchange.getRequest().getHeaders();

　　return new DefaultRequest<>(headers);

　　}

　　protected URI reconstructURI(ServiceInstance serviceInstance, URI original) {

　　return LoadBalancerUriTools.reconstructURI(serviceInstance, original);

　　}

　　@Override

　　public int getOrder() {

　　return LOAD_BALANCER_CLIENT_FILTER_ORDER;

　　}

　　}