SpringCloud gateway自定义请求的 httpClient

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。

原文链接：
https://www.cnblogs.com/zjdxr-up/p/16530423.html