要想了解spring cloud gateway的源碼，要熟悉spring webflux，我的上篇文章介紹了spring webflux。

1.gateway 和zuul對比

I am the author of spring cloud gateway. Zuul is built on servlet 2.5 (works with 3.x), using blocking APIs. It doesn't support any long lived connections, like websockets. Gateway is built on Spring Framework 5, Project Reactor and Spring Boot 2 using non-blocking APIs. Websockets are supported and it's a much better developer experience since it's tightly integrated with Spring.

簡單的來說：

　　1.zuul是基于servlet 2.5，兼容servlet3.0，使用的是阻塞API，不支持長連接如websocket

　　2.Gateway基于spring5，Reactor和Spring boot2使用了非阻塞API，支持websocket，和spring完美集成，對開發(fā)者友好。

　　另外

　　3.zuul2支持非阻塞API，但沒有和spring cloud集成，且已經(jīng)停止維護(hù)，不在考慮之列。

2.架構(gòu)圖

3.自動配置解析core spring.factories

# Auto Configure org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ org.springframework.cloud.gateway.config.GatewayClassPathWarningAutoConfiguration,\ org.springframework.cloud.gateway.config.GatewayAutoConfiguration,\ org.springframework.cloud.gateway.config.GatewayLoadBalancerClientAutoConfiguration,\ org.springframework.cloud.gateway.config.GatewayNoLoadBalancerClientAutoConfiguration,\ org.springframework.cloud.gateway.config.GatewayMetricsAutoConfiguration,\ org.springframework.cloud.gateway.config.GatewayRedisAutoConfiguration,\ org.springframework.cloud.gateway.discovery.GatewayDiscoveryClientAutoConfiguration org.springframework.boot.env.EnvironmentPostProcessor=\ org.springframework.cloud.gateway.config.GatewayEnvironmentPostProcessor

3.1?GatewayClassPathWarningAutoConfiguration檢查前端控制器

@Configuration@ConditionalOnClass(name = "org.springframework.web.servlet.DispatcherServlet")protected static class SpringMvcFoundOnClasspathConfiguration {public SpringMvcFoundOnClasspathConfiguration() {log.warn(BORDER+ "Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway at this time. "+ "Please remove spring-boot-starter-web dependency." + BORDER);}}@Configuration@ConditionalOnMissingClass("org.springframework.web.reactive.DispatcherHandler")protected static class WebfluxMissingFromClasspathConfiguration {public WebfluxMissingFromClasspathConfiguration() {log.warn(BORDER + "Spring Webflux is missing from the classpath, "+ "which is required for Spring Cloud Gateway at this time. "+ "Please add spring-boot-starter-webflux dependency." + BORDER);}}

1.若存在springmvc的前端控制器org.springframework.web.servlet.DispatcherServlet，則報(bào)警,原因是使用非阻塞的API

2.若不存在spring webflux的前端控制器org.springframework.web.reactive.DispatcherHandler，則報(bào)警,原因是需要使用非阻塞的API

3.2 網(wǎng)關(guān)自動配置GatewayAutoConfiguration

3.2.1?RoutePredicateHandlerMapping

@Beanpublic RoutePredicateHandlerMapping routePredicateHandlerMapping(FilteringWebHandler webHandler, RouteLocator routeLocator,GlobalCorsProperties globalCorsProperties, Environment environment) {return new RoutePredicateHandlerMapping(webHandler, routeLocator,globalCorsProperties, environment);}

RoutePredicateHandlerMapping繼承自AbstractHandlerMapping，在此步進(jìn)行路徑查找

@Overrideprotected Mono<?> getHandlerInternal(ServerWebExchange exchange) {// don't handle requests on the management port if setif (managmentPort != null&& exchange.getRequest().getURI().getPort() == managmentPort.intValue()) {return Mono.empty();}exchange.getAttributes().put(GATEWAY_HANDLER_MAPPER_ATTR, getSimpleName());return lookupRoute(exchange)// .log("route-predicate-handler-mapping", Level.FINER) //name this.flatMap((Function<Route, Mono<?>>) r -> {exchange.getAttributes().remove(GATEWAY_PREDICATE_ROUTE_ATTR);if (logger.isDebugEnabled()) {logger.debug("Mapping [" + getExchangeDesc(exchange) + "] to " + r);} exchange.getAttributes().put(GATEWAY_ROUTE_ATTR, r); //2return Mono.just(webHandler);}).switchIfEmpty(Mono.empty().then(Mono.fromRunnable(() -> {exchange.getAttributes().remove(GATEWAY_PREDICATE_ROUTE_ATTR);if (logger.isTraceEnabled()) {logger.trace("No RouteDefinition found for ["+ getExchangeDesc(exchange) + "]");}})));}protected Mono<Route> lookupRoute(ServerWebExchange exchange) {//1return this.routeLocator.getRoutes()// individually filter routes so that filterWhen error delaying is not a// problem.concatMap(route -> Mono.just(route).filterWhen(r -> {// add the current route we are testing exchange.getAttributes().put(GATEWAY_PREDICATE_ROUTE_ATTR, r.getId());return r.getPredicate().apply(exchange);})// instead of immediately stopping main flux due to error, log and// swallow it.doOnError(e -> logger.error("Error applying predicate for route: " + route.getId(),e)).onErrorResume(e -> Mono.empty()))// .defaultIfEmpty() put a static Route not found// or .switchIfEmpty()// .switchIfEmpty(Mono.<Route>empty().log("noroute")) .next()// TODO: error handling.map(route -> {if (logger.isDebugEnabled()) {logger.debug("Route matched: " + route.getId());}validateRoute(route, exchange);return route;});/** TODO: trace logging if (logger.isTraceEnabled()) {* logger.trace("RouteDefinition did not match: " + routeDefinition.getId()); }*/}

?1.通過RouteLocator返回Route

?

?關(guān)于Route的定義

private Route(String id, URI uri, int order,AsyncPredicate<ServerWebExchange> predicate,List<GatewayFilter> gatewayFilters) {this.id = id;this.uri = uri;this.order = order;this.predicate = predicate;this.gatewayFilters = gatewayFilters;}

可以看出url和gatewayFilter進(jìn)行了綁定

?2.將Route放入ServerWebExchange的屬性中。

3.2.2?FilteringWebHandler

@Beanpublic FilteringWebHandler filteringWebHandler(List<GlobalFilter> globalFilters) {return new FilteringWebHandler(globalFilters);}

?

?

參考文獻(xiàn)：

【1】https://stackoverflow.com/questions/47092048/how-spring-cloud-gateway-is-different-from-zuul

【2】https://blog.csdn.net/xuejike/article/details/81290695

轉(zhuǎn)載于:https://www.cnblogs.com/davidwang456/p/10402768.html

總結(jié)

以上是生活随笔為你收集整理的api网关揭秘--spring cloud gateway源码解析的全部內(nèi)容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網(wǎng)站內(nèi)容還不錯，歡迎將生活随笔推薦給好友。