SpringCloud gateway自定义请求的 httpClient

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　　引用 的 spring cloud gateway 的版本为 2.2.5 ；

　　SpringCloud gateway 在实现服务路由并请求的具体过程是在 org.springframework.cloud.gateway.filter.NettyRoutingFilter 的过滤器中，该过滤器封装了具体的请求参数，以及根据路由规则请求的对应服务，然后根据 HttpClient 进行微服务之间的请求； 该 httpClient 类是 用netty 封装的 客户端，其包路径为 ： reactor.netty.http.client.HttpClient ;

　　查看 NettyRoutingFilter 中的 filter 实现过程：

    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {         URI requestUrl = (URI)exchange.getRequiredAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);         String scheme = requestUrl.getScheme();         if (!ServerWebExchangeUtils.isAlreadyRouted(exchange) && ("http".equals(scheme) || "https".equals(scheme))) {             ServerWebExchangeUtils.setAlreadyRouted(exchange);             ServerHttpRequest request = exchange.getRequest();             HttpMethod method = HttpMethod.valueOf(request.getMethodValue());             String url = requestUrl.toASCIIString();             HttpHeaders filtered = HttpHeadersFilter.filterRequest(this.getHeadersFilters(), exchange);             DefaultHttpHeaders httpHeaders = new DefaultHttpHeaders();             filtered.forEach(httpHeaders::set);             boolean preserveHost = (Boolean)exchange.getAttributeOrDefault(ServerWebExchangeUtils.PRESERVE_HOST_HEADER_ATTRIBUTE, false);             Route route = (Route)exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_ROUTE_ATTR);             Flux<HttpClientResponse> responseFlux = ((RequestSender)this.getHttpClient(route, exchange).headers((headers) -> {                 headers.add(httpHeaders);                 headers.remove("Host");                 if (preserveHost) {                     String host = request.getHeaders().getFirst("Host");                     headers.add("Host", host);                 }              }).request(method).uri(url)).send((req, nettyOutbound) -> {                 if (log.isTraceEnabled()) {                     nettyOutbound.withConnection((connection) -> {                         log.trace("outbound route: " + connection.channel().id().asShortText() + ", inbound: " + exchange.getLogPrefix());                     });                 }                  return nettyOutbound.send(request.getBody().map(this::getByteBuf));             }).responseConnection((res, connection) -> {                 exchange.getAttributes().put(ServerWebExchangeUtils.CLIENT_RESPONSE_ATTR, res);                 exchange.getAttributes().put(ServerWebExchangeUtils.CLIENT_RESPONSE_CONN_ATTR, connection);                 ServerHttpResponse response = exchange.getResponse();                 HttpHeaders headers = new HttpHeaders();                 res.responseHeaders().forEach((entry) -> {                     headers.add((String)entry.getKey(), (String)entry.getValue());                 });                 String contentTypeValue = headers.getFirst("Content-Type");                 if (StringUtils.hasLength(contentTypeValue)) {                     exchange.getAttributes().put("original_response_content_type", contentTypeValue);                 }                  this.setResponseStatus(res, response);                 HttpHeaders filteredResponseHeaders = HttpHeadersFilter.filter(this.getHeadersFilters(), headers, exchange, Type.RESPONSE);                 if (!filteredResponseHeaders.containsKey("Transfer-Encoding") && filteredResponseHeaders.containsKey("Content-Length")) {                     response.getHeaders().remove("Transfer-Encoding");                 }                  exchange.getAttributes().put(ServerWebExchangeUtils.CLIENT_RESPONSE_HEADER_NAMES, filteredResponseHeaders.keySet());                 response.getHeaders().putAll(filteredResponseHeaders);                 return Mono.just(res);             });             Duration responseTimeout = this.getResponseTimeout(route);             if (responseTimeout != null) {                 responseFlux = responseFlux.timeout(responseTimeout, Mono.error(new TimeoutException("Response took longer than timeout: " + responseTimeout))).onErrorMap(TimeoutException.class, (th) -> {                     return new ResponseStatusException(HttpStatus.GATEWAY_TIMEOUT, th.getMessage(), th);                 });             }              return responseFlux.then(chain.filter(exchange));         } else {             return chain.filter(exchange);         }     }

　　

　　该方法中 有一个 getHttpClient 方法获取 httpClient 客户端实例的过程，由于在  GatewayAutoConfiguration 中 定义了 springCloud gateway 使用的 httpclient 实例，其声明并自动加载的代码如下：

@Configuration(         proxyBeanMethods = false     )     @ConditionalOnClass({HttpClient.class})     protected static class NettyConfiguration {         protected final Log logger = LogFactory.getLog(this.getClass());          protected NettyConfiguration() {         }          @Bean         @ConditionalOnProperty(             name = {"spring.cloud.gateway.httpserver.wiretap"}         )         public NettyWebServerFactoryCustomizer nettyServerWiretapCustomizer(Environment environment, ServerProperties serverProperties) {             return new NettyWebServerFactoryCustomizer(environment, serverProperties) {                 public void customize(NettyReactiveWebServerFactory factory) {                     factory.addServerCustomizers(new NettyServerCustomizer[]{(httpServer) -> {                         return httpServer.wiretap(true);                     }});                     super.customize(factory);                 }             };         }          @Bean         @ConditionalOnMissingBean         public HttpClient gatewayHttpClient(HttpClientProperties properties, List<HttpClientCustomizer> customizers) {             Pool pool = properties.getPool();             ConnectionProvider connectionProvider;             if (pool.getType() == PoolType.DISABLED) {                 connectionProvider = ConnectionProvider.newConnection();             } else if (pool.getType() == PoolType.FIXED) {                 connectionProvider = ConnectionProvider.fixed(pool.getName(), pool.getMaxConnections(), pool.getAcquireTimeout(), pool.getMaxIdleTime(), pool.getMaxLifeTime());             } else {                 connectionProvider = ConnectionProvider.elastic(pool.getName(), pool.getMaxIdleTime(), pool.getMaxLifeTime());             }              HttpClient httpClient = HttpClient.create(connectionProvider).httpResponseDecoder((spec) -> {                 if (properties.getMaxHeaderSize() != null) {                     spec.maxHeaderSize((int)properties.getMaxHeaderSize().toBytes());                 }                  if (properties.getMaxInitialLineLength() != null) {                     spec.maxInitialLineLength((int)properties.getMaxInitialLineLength().toBytes());                 }                  return spec;             }).tcpConfiguration((tcpClient) -> {                 if (properties.getConnectTimeout() != null) {                     tcpClient = tcpClient.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, properties.getConnectTimeout());                 }                  Proxy proxy = properties.getProxy();                 if (StringUtils.hasText(proxy.getHost())) {                     tcpClient = tcpClient.proxy((proxySpec) -> {                         Builder builder = proxySpec.type(reactor.netty.tcp.ProxyProvider.Proxy.HTTP).host(proxy.getHost());                         PropertyMapper map = PropertyMapper.get();                         proxy.getClass();                         map.from(proxy::getPort).whenNonNull().to(builder::port);                         proxy.getClass();                         map.from(proxy::getUsername).whenHasText().to(builder::username);                         proxy.getClass();                         map.from(proxy::getPassword).whenHasText().to((password) -> {                             builder.password((s) -> {                                 return password;                             });                         });                         proxy.getClass();                         map.from(proxy::getNonProxyHostsPattern).whenHasText().to(builder::nonProxyHosts);                     });                 }                  return tcpClient;             });             Ssl ssl = properties.getSsl();             if (ssl.getKeyStore() != null && ssl.getKeyStore().length() > 0 || ssl.getTrustedX509CertificatesForTrustManager().length > 0 || ssl.isUseInsecureTrustManager()) {                 httpClient = httpClient.secure((sslContextSpec) -> {                     SslContextBuilder sslContextBuilder = SslContextBuilder.forClient();                     X509Certificate[] trustedX509Certificates = ssl.getTrustedX509CertificatesForTrustManager();                     if (trustedX509Certificates.length > 0) {                         sslContextBuilder = sslContextBuilder.trustManager(trustedX509Certificates);                     } else if (ssl.isUseInsecureTrustManager()) {                         sslContextBuilder = sslContextBuilder.trustManager(InsecureTrustManagerFactory.INSTANCE);                     }                      try {                         sslContextBuilder = sslContextBuilder.keyManager(ssl.getKeyManagerFactory());                     } catch (Exception var6) {                         this.logger.error(var6);                     }                      sslContextSpec.sslContext(sslContextBuilder).defaultConfiguration(ssl.getDefaultConfigurationType()).handshakeTimeout(ssl.getHandshakeTimeout()).closeNotifyFlushTimeout(ssl.getCloseNotifyFlushTimeout()).closeNotifyReadTimeout(ssl.getCloseNotifyReadTimeout());                 });             }              if (properties.isWiretap()) {                 httpClient = httpClient.wiretap(true);             }              if (!CollectionUtils.isEmpty(customizers)) {                 customizers.sort(AnnotationAwareOrderComparator.INSTANCE);                  HttpClientCustomizer customizer;                 for(Iterator var7 = customizers.iterator(); var7.hasNext(); httpClient = customizer.customize(httpClient)) {                     customizer = (HttpClientCustomizer)var7.next();                 }             }              return httpClient;         }          @Bean         public HttpClientProperties httpClientProperties() {             return new HttpClientProperties();         }          @Bean         public NettyRoutingFilter routingFilter(HttpClient httpClient, ObjectProvider<List<HttpHeadersFilter>> headersFilters, HttpClientProperties properties) {             return new NettyRoutingFilter(httpClient, headersFilters, properties);         }          @Bean         public NettyWriteResponseFilter nettyWriteResponseFilter(GatewayProperties properties) {             return new NettyWriteResponseFilter(properties.getStreamingMediaTypes());         }          @Bean         public ReactorNettyWebSocketClient reactorNettyWebSocketClient(HttpClientProperties properties, HttpClient httpClient) {             ReactorNettyWebSocketClient webSocketClient = new ReactorNettyWebSocketClient(httpClient);             if (properties.getWebsocket().getMaxFramePayloadLength() != null) {                 webSocketClient.setMaxFramePayloadLength(properties.getWebsocket().getMaxFramePayloadLength());             }              webSocketClient.setHandlePing(properties.getWebsocket().isProxyPing());             return webSocketClient;         }          @Bean         public ReactorNettyRequestUpgradeStrategy reactorNettyRequestUpgradeStrategy(HttpClientProperties httpClientProperties) {             ReactorNettyRequestUpgradeStrategy requestUpgradeStrategy = new ReactorNettyRequestUpgradeStrategy();             Websocket websocket = httpClientProperties.getWebsocket();             PropertyMapper map = PropertyMapper.get();             websocket.getClass();             map.from(websocket::getMaxFramePayloadLength).whenNonNull().to(requestUpgradeStrategy::setMaxFramePayloadLength);             websocket.getClass();             map.from(websocket::isProxyPing).to(requestUpgradeStrategy::setHandlePing);             return requestUpgradeStrategy;         }     }

　　上面 代码中的 gatewayHttpClient 为 spring cloud gateway 使用的 HttpClient 实例，在spring cloud gateway 进行服务请求时，会自动配置使用该 实例。

　　如果需要自定义的 HttpClient 实例，如在 httpClient 中自定义 ip 白名单校验，https 请求证书预置，或是添加特殊认证请求头等，这种场景下需要在代码中显示的定义 gatewayHttpClient 实例，代码如下：

    @Configuration     public class GatewayAutoConfiguration {          @Bean         @ConditionalOnMissingBean         public HttpClient gatewayHttpClient(HttpClientProperties properties, List<HttpClientCustomizer> customizers) {             Pool pool = properties.getPool();             ConnectionProvider connectionProvider;             if (pool.getType() == PoolType.DISABLED) {                 connectionProvider = ConnectionProvider.newConnection();             } else if (pool.getType() == PoolType.FIXED) {                 connectionProvider = ConnectionProvider.fixed(pool.getName(), pool.getMaxConnections(), pool.getAcquireTimeout(), pool.getMaxIdleTime(), pool.getMaxLifeTime());             } else {                 connectionProvider = ConnectionProvider.elastic(pool.getName(), pool.getMaxIdleTime(), pool.getMaxLifeTime());             }              HttpClient httpClient = HttpClient.create(connectionProvider).httpResponseDecoder((spec) -> {                 if (properties.getMaxHeaderSize() != null) {                     spec.maxHeaderSize((int)properties.getMaxHeaderSize().toBytes());                 }                  if (properties.getMaxInitialLineLength() != null) {                     spec.maxInitialLineLength((int)properties.getMaxInitialLineLength().toBytes());                 }                  return spec;             }).tcpConfiguration((tcpClient) -> {                 if (properties.getConnectTimeout() != null) {                     tcpClient = tcpClient.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, properties.getConnectTimeout());                 }                  Proxy proxy = properties.getProxy();                 if (StringUtils.hasText(proxy.getHost())) {                     tcpClient = tcpClient.proxy((proxySpec) -> {                         Builder builder = proxySpec.type(reactor.netty.tcp.ProxyProvider.Proxy.HTTP).host(proxy.getHost());                         PropertyMapper map = PropertyMapper.get();                         proxy.getClass();                         map.from(proxy::getPort).whenNonNull().to(builder::port);                         proxy.getClass();                         map.from(proxy::getUsername).whenHasText().to(builder::username);                         proxy.getClass();                         map.from(proxy::getPassword).whenHasText().to((password) -> {                             builder.password((s) -> {                                 return password;                             });                         });                         proxy.getClass();                         map.from(proxy::getNonProxyHostsPattern).whenHasText().to(builder::nonProxyHosts);                     });                 }                  return tcpClient;             });             Ssl ssl = properties.getSsl();             if (ssl.getKeyStore() != null && ssl.getKeyStore().length() > 0 || ssl.getTrustedX509CertificatesForTrustManager().length > 0 || ssl.isUseInsecureTrustManager()) {                 httpClient = httpClient.secure((sslContextSpec) -> {                     SslContextBuilder sslContextBuilder = SslContextBuilder.forClient();                     X509Certificate[] trustedX509Certificates = ssl.getTrustedX509CertificatesForTrustManager();                     if (trustedX509Certificates.length > 0) {                         sslContextBuilder = sslContextBuilder.trustManager(trustedX509Certificates);                     } else if (ssl.isUseInsecureTrustManager()) {                         sslContextBuilder = sslContextBuilder.trustManager(InsecureTrustManagerFactory.INSTANCE);                     }                      try {                         sslContextBuilder = sslContextBuilder.keyManager(ssl.getKeyManagerFactory());                     } catch (Exception var6) {                         this.logger.error(var6);                     }                      sslContextSpec.sslContext(sslContextBuilder).defaultConfiguration(ssl.getDefaultConfigurationType()).handshakeTimeout(ssl.getHandshakeTimeout()).closeNotifyFlushTimeout(ssl.getCloseNotifyFlushTimeout()).closeNotifyReadTimeout(ssl.getCloseNotifyReadTimeout());                 });             }              if (properties.isWiretap()) {                 httpClient = httpClient.wiretap(true);             }              if (!CollectionUtils.isEmpty(customizers)) {                 customizers.sort(AnnotationAwareOrderComparator.INSTANCE);                  HttpClientCustomizer customizer;                 for(Iterator var7 = customizers.iterator(); var7.hasNext(); httpClient = customizer.customize(httpClient)) {                     customizer = (HttpClientCustomizer)var7.next();                 }             }              return httpClient;         }              }    

　　　这样服务在启动的时候就会优先加载自定的 httpClient 实例。