学做网站都要学什么专业,设计工作室网站源码,大作设计app,公司做网站属于什么费用上一节做了一个很简单的示例#xff0c;微服务通过注册到eureka上#xff0c;然后网关通过服务发现访问到对应的微服务。本节将简单地对整个gateway请求转发过程做一个简单的分析。
一、核心流程 主要流程#xff1a;
Gateway Client向 Spring Cloud Gateway 发送请求请求…上一节做了一个很简单的示例微服务通过注册到eureka上然后网关通过服务发现访问到对应的微服务。本节将简单地对整个gateway请求转发过程做一个简单的分析。
一、核心流程 主要流程
Gateway Client向 Spring Cloud Gateway 发送请求请求首先会被HttpWebHandlerAdapter 进行提取组装成网关上下文然后网关的上下文会传递到DispatcherHandler 它负责将请求分发给 RoutePredicateHandlerMappingRoutePredicateHandlerMapping负责路由查找并根据路由断言判断路由是否可用如果过断言成功由FilteringWebHandler 创建过滤器链并调用通过特定于请求的 Fliter 链运行请求Filter 被虚线分隔的原因是Filter可以在发送代理请求之前pre和之后post运行逻辑执行所有pre过滤器逻辑。然后进行代理请求。发出代理请求后将运行“post”过滤器逻辑。处理完毕之后将 Response 返回到 Gateway 客户端
二、具体分析
请求过来会经过HttpWebHandlerAdapter.handle方法可以理解为这就是请求的主入口
Override
public MonoVoid handle(ServerHttpRequest request, ServerHttpResponse response) {if (this.forwardedHeaderTransformer ! null) {try {request this.forwardedHeaderTransformer.apply(request);}catch (Throwable ex) {if (logger.isDebugEnabled()) {logger.debug(Failed to apply forwarded headers to formatRequest(request), ex);}response.setStatusCode(HttpStatus.BAD_REQUEST);return response.setComplete();}}//组装上下文ServerWebExchange exchange createExchange(request, response);LogFormatUtils.traceDebug(logger, traceOn -exchange.getLogPrefix() formatRequest(exchange.getRequest()) (traceOn ? , headers formatHeaders(exchange.getRequest().getHeaders()) : ));
//委派给delegate来处理return getDelegate().handle(exchange).doOnSuccess(aVoid - logResponse(exchange)).onErrorResume(ex - handleUnresolvedError(exchange, ex)).then(Mono.defer(response::setComplete));
}这一个delegate是个啥看一下接口定义 就是一个处理器所有参数封装在上下文exchange中
public interface WebHandler {/*** Handle the web server exchange.* param exchange the current server exchange* return {code MonoVoid} to indicate when request handling is complete*/MonoVoid handle(ServerWebExchange exchange);}最终会调到DispatcherHandler
Override
public MonoVoid handle(ServerWebExchange exchange) {if (this.handlerMappings null) {return createNotFoundError();}if (CorsUtils.isPreFlightRequest(exchange.getRequest())) {return handlePreFlight(exchange);}return Flux.fromIterable(this.handlerMappings).concatMap(mapping - mapping.getHandler(exchange)).next().switchIfEmpty(createNotFoundError()).flatMap(handler - invokeHandler(exchange, handler)).flatMap(result - handleResult(exchange, result));
}handlerMappings是啥 是一个列表HandlerMapping可以根据当前请求找到对应的处理器 如果当前请求比如/hello/world在gateway服务上是一个controller对应的接口那这个就可以通过RequestMappingHandlerMapping找到一个RequestMappingHandlerAdapter。 如果当前请求是需要转发给下游微服务的则找到RoutePredicateHandlerMapping RoutePredicateHandlerMapping查找路由主要逻辑
Override
protected Mono? getHandlerInternal(ServerWebExchange exchange) {// dont handle requests on management port if set and different than server portif (this.managementPortType DIFFERENT this.managementPort ! null exchange.getRequest().getLocalAddress() ! null exchange.getRequest().getLocalAddress().getPort() this.managementPort) {return Mono.empty();}exchange.getAttributes().put(GATEWAY_HANDLER_MAPPER_ATTR, getSimpleName());return lookupRoute(exchange)// .log(route-predicate-handler-mapping, Level.FINER) //name this.flatMap((FunctionRoute, Mono?) r - {exchange.getAttributes().remove(GATEWAY_PREDICATE_ROUTE_ATTR);if (logger.isDebugEnabled()) {logger.debug(Mapping [ getExchangeDesc(exchange) ] to r);}//把找到的路由放到exchange上下文中exchange.getAttributes().put(GATEWAY_ROUTE_ATTR, r);//返回的handler实际上是webHandlerreturn 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) ]);}})));
}看下查找路由的具体方式原来是将所有的路由用predicate作一下匹配找出符合当前请求的路由
protected MonoRoute lookupRoute(ServerWebExchange exchange) {return 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 testingexchange.getAttributes().put(GATEWAY_PREDICATE_ROUTE_ATTR, r.getId());//用predicate作一下匹配找出符合当前请求的路由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.Routeempty().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()); }*/
}routeLocator包含了哪些路由Debug看一下
可以看到用了服务注册和发现后实际上一个微服务会自动注册一个路由比如上面的hello-service自动注册了一个路径为/hello-service/**的路由。这就是为什么我们yml配置文件中明明什么路由也没有配置也能自动转发hello-service的请求。 同时可以看到这个路由下面有一个ReWritePathFilter会自动去掉服务名将请求转发给下游微服务。
下一步再看看FilteringWebHandler中的处理逻辑
Override
public MonoVoid handle(ServerWebExchange exchange) {
//从上下文中取出路由路由中包含filtersRoute route exchange.getRequiredAttribute(GATEWAY_ROUTE_ATTR);ListGatewayFilter gatewayFilters route.getFilters();
//spring容器中的Global Filter也取出来ListGatewayFilter combined new ArrayList(this.globalFilters);combined.addAll(gatewayFilters);// TODO: needed or cached?//做个排序AnnotationAwareOrderComparator.sort(combined);if (logger.isDebugEnabled()) {logger.debug(Sorted gatewayFilterFactories: combined);}
//后面就是filter链式调用了return new DefaultGatewayFilterChain(combined).filter(exchange);
}可以看到代码中主要有两个逻辑 1、从上下文中取出路由路由中包含filters 2、spring容器中的Global Filter也取出来 3、合并上面的两种filter,并且排序 4、filters列表组装成责任链来进行调用 可以通过源码再来看看核心流程的那个图这样就比较清楚了。 总结了另一个稍微详细一点的图
个人看这块源码的体会整个核心流程并不复杂难点大概是reactor响应式编程如果之前没接触过这一块那么看着会有种不知道下一步往哪里的困惑所以要学习这块源码还得学习reactor。
