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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。