28、SpringCloud Alibaba - spring cloud gateway 的启动流程
启动过程中会加载和注册一些配置类和主要类。
1、 GatewayClassPathWarningAutoConfiguration；
1、存在DispatcherServlet 时提示移除spring-boot-starter-web依赖
2、不存在DispatcherHandler时提示添加spring-boot-starter-webflux依赖
@Configuration(proxyBeanMethods = false)
@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(proxyBeanMethods = false)
@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);
}
}
2、 GatewayReactiveLoadBalancerClientAutoConfiguration；
ReactiveLoadBalancerClientFilter 负载均衡客户端过滤器
@Bean
@ConditionalOnBean(LoadBalancerClientFactory.class)
@ConditionalOnMissingBean(ReactiveLoadBalancerClientFilter.class)
@ConditionalOnEnabledGlobalFilter
public ReactiveLoadBalancerClientFilter gatewayLoadBalancerClientFilter(LoadBalancerClientFactory clientFactory,
GatewayLoadBalancerProperties properties, LoadBalancerProperties loadBalancerProperties) {
//封装了LoadBalancerClientFactory和一些负载均衡配置信息
return new ReactiveLoadBalancerClientFilter(clientFactory, properties, loadBalancerProperties);
}
3、 LoadBalancerAutoConfiguration；
LoadBalancerClientFactory 负载均衡客户端工厂
@ConditionalOnMissingBean
@Bean
public LoadBalancerClientFactory loadBalancerClientFactory() {
LoadBalancerClientFactory clientFactory = new LoadBalancerClientFactory();
clientFactory.setConfigurations(this.configurations.getIfAvailable(Collections::emptyList));
return clientFactory;
}
4、 GatewayProperties；
网关的配置信息，从配置文件中加载 spring.cloud.gateway 相关路由、过滤器等信息
5、 RouteLocator；
1、DiscoveryClientRouteDefinitionLocator
服务发现客户端路由，例如从nacos服务端获取的服务信息
2、PropertiesRouteDefinitionLocator
获取GatewayProperties 配置文件中的路由信息
@Override
public Flux<RouteDefinition> getRouteDefinitions() {
return Flux.fromIterable(this.properties.getRoutes());
}
3、InMemoryRouteDefinitionRepository
获取内存中的路由信息
@Override
public Flux<RouteDefinition> getRouteDefinitions() {
return Flux.fromIterable(routes.values());
}
注册路由是通过 AbstractGatewayControllerEndpoint 接口
@PostMapping("/routes/{id}")
@SuppressWarnings("unchecked")
public Mono<ResponseEntity<Object>> save(@PathVariable String id, @RequestBody RouteDefinition route) {
return Mono.just(route).filter(this::validateRouteDefinition)
//保存
.flatMap(routeDefinition -> this.routeDefinitionWriter.save(Mono.just(routeDefinition).map(r -> {
r.setId(id);
log.debug("Saving route: " + route);
return r;
})).then(Mono.defer(() -> Mono.just(ResponseEntity.created(URI.create("/routes/" + id)).build()))))
.switchIfEmpty(Mono.defer(() -> Mono.just(ResponseEntity.badRequest().build())));
}
@Override
public Mono<Void> save(Mono<RouteDefinition> route) {
return route.flatMap(r -> {
if (ObjectUtils.isEmpty(r.getId())) {
return Mono.error(new IllegalArgumentException("id may not be empty"));
}
//放入内存
routes.put(r.getId(), r);
return Mono.empty();
});
}
4、CompositeRouteDefinitionLocator
组合路由信息，传入DiscoveryClientRouteDefinitionLocator、PropertiesRouteDefinitionLocator、InMemoryRouteDefinitionRepository
@Override
public Flux<RouteDefinition> getRouteDefinitions() {
//合并路由信息
return this.delegates.flatMapSequential(RouteDefinitionLocator::getRouteDefinitions)
.flatMap(routeDefinition -> {
if (routeDefinition.getId() == null) {
return randomId().map(id -> {
routeDefinition.setId(id);
if (log.isDebugEnabled()) {
log.debug("Id set on route definition: " + routeDefinition);
}
return routeDefinition;
});
}
return Mono.just(routeDefinition);
});
}
5、RouteDefinitionRouteLocator
传入CompositeRouteDefinitionLocator、gatewayFilters、predicates 等
public RouteDefinitionRouteLocator(RouteDefinitionLocator routeDefinitionLocator,
List<RoutePredicateFactory> predicates, List<GatewayFilterFactory> gatewayFilterFactories,
GatewayProperties gatewayProperties, ConfigurationService configurationService) {
this.routeDefinitionLocator = routeDefinitionLocator;
this.configurationService = configurationService;
initFactories(predicates);
gatewayFilterFactories.forEach(factory -> this.gatewayFilterFactories.put(factory.name(), factory));
this.gatewayProperties = gatewayProperties;
}
6、CompositeRouteLocator
包装RouteDefinitionRouteLocator
@Override
public Flux<RouteDefinition> getRouteDefinitions() {
//从 RouteDefinitionRouteLocator 中获取路由
return this.delegates.flatMapSequential(RouteDefinitionLocator::getRouteDefinitions)
.flatMap(routeDefinition -> {
if (routeDefinition.getId() == null) {
return randomId().map(id -> {
routeDefinition.setId(id);
if (log.isDebugEnabled()) {
log.debug("Id set on route definition: " + routeDefinition);
}
return routeDefinition;
});
}
return Mono.just(routeDefinition);
});
}
7、CachingRouteLocator
包装CompositeRouteLocator
@Override
public void onApplicationEvent(RefreshRoutesEvent event) {
try {
fetch().collect(Collectors.toList()).subscribe(
list -> Flux.fromIterable(list).materialize().collect(Collectors.toList()).subscribe(signals -> {
//发布 RefreshRoutesResultEvent 事件
applicationEventPublisher.publishEvent(new RefreshRoutesResultEvent(this));
//放入缓存
cache.put(CACHE_KEY, signals);
}, this::handleRefreshError), this::handleRefreshError);
}
catch (Throwable e) {
handleRefreshError(e);
}
}
6、 RouteRefreshListener；
路由刷新监听器，接收ContextRefreshedEvent、RefreshScopeRefreshedEvent、InstanceRegisteredEvent、ParentHeartbeatEvent、HeartbeatEvent，并发布 RefreshRoutesEvent 事件
public void onApplicationEvent(ApplicationEvent event) {
if (event instanceof ContextRefreshedEvent) {
ContextRefreshedEvent refreshedEvent = (ContextRefreshedEvent) event;
if (!WebServerApplicationContext.hasServerNamespace(refreshedEvent.getApplicationContext(), "management")) {
reset();
}
}
else if (event instanceof RefreshScopeRefreshedEvent || event instanceof InstanceRegisteredEvent) {
reset();
}
else if (event instanceof ParentHeartbeatEvent) {
ParentHeartbeatEvent e = (ParentHeartbeatEvent) event;
resetIfNeeded(e.getValue());
}
else if (event instanceof HeartbeatEvent) {
HeartbeatEvent e = (HeartbeatEvent) event;
resetIfNeeded(e.getValue());
}
}
private void reset() {
this.publisher.publishEvent(new RefreshRoutesEvent(this));
}
7、 FilteringWebHandler；
请求处理器，将 GlobalFilter 转换成 GatewayFilter，处理请求的filter 链
public FilteringWebHandler(List<GlobalFilter> globalFilters) {
this.globalFilters = loadFilters(globalFilters);
}
private static List<GatewayFilter> loadFilters(List<GlobalFilter> filters) {
return filters.stream().map(filter -> {
GatewayFilterAdapter gatewayFilter = new GatewayFilterAdapter(filter);
if (filter instanceof Ordered) {
int order = ((Ordered) filter).getOrder();
return new OrderedGatewayFilter(gatewayFilter, order);
}
return gatewayFilter;
}).collect(Collectors.toList());
}
8、 RoutePredicateHandlerMapping；
路由的处理器映射器，包含了webHandler、routeLocator等，用于查找出对应路由
public RoutePredicateHandlerMapping(FilteringWebHandler webHandler, RouteLocator routeLocator,
GlobalCorsProperties globalCorsProperties, Environment environment) {
this.webHandler = webHandler;
this.routeLocator = routeLocator;
this.managementPort = getPortProperty(environment, "management.server.");
this.managementPortType = getManagementPortType(environment);
setOrder(1);
setCorsConfigurations(globalCorsProperties.getCorsConfigurations());
}
9、 DispatcherHandler；
初始化HandlerMapping、HandlerAdapter、HandlerResultHandler
@Override
public void setApplicationContext(ApplicationContext applicationContext) {
initStrategies(applicationContext);
}
protected void initStrategies(ApplicationContext context) {
//找出 HandlerMapping.class
Map<String, HandlerMapping> mappingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(
context, HandlerMapping.class, true, false);
ArrayList<HandlerMapping> mappings = new ArrayList<>(mappingBeans.values());
AnnotationAwareOrderComparator.sort(mappings);
this.handlerMappings = Collections.unmodifiableList(mappings);
//找出 HandlerAdapter.class
Map<String, HandlerAdapter> adapterBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(
context, HandlerAdapter.class, true, false);
this.handlerAdapters = new ArrayList<>(adapterBeans.values());
AnnotationAwareOrderComparator.sort(this.handlerAdapters);
//找出 HandlerResultHandler.class
Map<String, HandlerResultHandler> beans = BeanFactoryUtils.beansOfTypeIncludingAncestors(
context, HandlerResultHandler.class, true, false);
this.resultHandlers = new ArrayList<>(beans.values());
AnnotationAwareOrderComparator.sort(this.resultHandlers);
}