聊聊spring cloud gateway的RouteLocator-白红宇

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本文主要研究一下spring cloud gateway的RouteLocator

RouteLocator

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/route/RouteLocator.java

public interface RouteLocator {	Flux
    
      getRoutes();}复制代码

其有三个实现类：

RouteDefinitionRouteLocator

CompositeRouteLocator

CachingRouteLocator

GatewayAutoConfiguration

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@Configuration@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)@EnableConfigurationProperties@AutoConfigureBefore(HttpHandlerAutoConfiguration.class)@AutoConfigureAfter({GatewayLoadBalancerClientAutoConfiguration.class, GatewayClassPathWarningAutoConfiguration.class})@ConditionalOnClass(DispatcherHandler.class)public class GatewayAutoConfiguration {	//......	@Bean	public RouteLocatorBuilder routeLocatorBuilder(ConfigurableApplicationContext context) {		return new RouteLocatorBuilder(context);	}	@Bean	public RouteLocator routeDefinitionRouteLocator(GatewayProperties properties,												   List
    
      GatewayFilters,												   List
     
       predicates,												   RouteDefinitionLocator routeDefinitionLocator) {		return new RouteDefinitionRouteLocator(routeDefinitionLocator, predicates, GatewayFilters, properties);	}	@Bean	@Primary	//TODO: property to disable composite?	public RouteLocator cachedCompositeRouteLocator(List
      
        routeLocators) {		return new CachingRouteLocator(new CompositeRouteLocator(Flux.fromIterable(routeLocators)));	}	@Bean	public RoutePredicateHandlerMapping routePredicateHandlerMapping(FilteringWebHandler webHandler,																	   RouteLocator routeLocator) {		return new RoutePredicateHandlerMapping(webHandler, routeLocator);	}	@Configuration	@ConditionalOnClass(Health.class)	protected static class GatewayActuatorConfiguration {		@Bean		@ConditionalOnEnabledEndpoint		public GatewayControllerEndpoint gatewayControllerEndpoint(RouteDefinitionLocator routeDefinitionLocator, List
       
         globalFilters,																List
        
          GatewayFilters, RouteDefinitionWriter routeDefinitionWriter,																RouteLocator routeLocator) {			return new GatewayControllerEndpoint(routeDefinitionLocator, globalFilters, GatewayFilters, routeDefinitionWriter, routeLocator);		}	}	//......}复制代码

可以看到默认创建了RouteDefinitionRouteLocator，然后又基于它创建了CompositeRouteLocator，最后由CachingRouteLocator再包装一层

RouteDefinitionRouteLocator

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/route/RouteDefinitionRouteLocator.java

/** * {@link RouteLocator} that loads routes from a {@link RouteDefinitionLocator} * @author Spencer Gibb */public class RouteDefinitionRouteLocator implements RouteLocator, BeanFactoryAware, ApplicationEventPublisherAware {	protected final Log logger = LogFactory.getLog(getClass());	private final RouteDefinitionLocator routeDefinitionLocator;	private final Map
    
      predicates = new LinkedHashMap<>();	private final Map
     
       gatewayFilterFactories = new HashMap<>();	private final GatewayProperties gatewayProperties;	private final SpelExpressionParser parser = new SpelExpressionParser();	private BeanFactory beanFactory;	private ApplicationEventPublisher publisher;	public RouteDefinitionRouteLocator(RouteDefinitionLocator routeDefinitionLocator,									   List
      
        predicates,									   List
       
         gatewayFilterFactories,									   GatewayProperties gatewayProperties) {		this.routeDefinitionLocator = routeDefinitionLocator;		initFactories(predicates);		gatewayFilterFactories.forEach(factory -> this.gatewayFilterFactories.put(factory.name(), factory));		this.gatewayProperties = gatewayProperties;	}	@Autowired	private Validator validator;	@Override	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {		this.beanFactory = beanFactory;	}	@Override	public void setApplicationEventPublisher(ApplicationEventPublisher publisher) {		this.publisher = publisher;	}	private void initFactories(List
        
          predicates) {		predicates.forEach(factory -> {			String key = factory.name();			if (this.predicates.containsKey(key)) {				this.logger.warn("A RoutePredicateFactory named "+ key						+ " already exists, class: " + this.predicates.get(key)						+ ". It will be overwritten.");			}			this.predicates.put(key, factory);			if (logger.isInfoEnabled()) {				logger.info("Loaded RoutePredicateFactory [" + key + "]");			}		});	}	@Override	public Flux
         
           getRoutes() { return this.routeDefinitionLocator.getRouteDefinitions() .map(this::convertToRoute) //TODO: error handling .map(route -> { if (logger.isDebugEnabled()) { logger.debug("RouteDefinition matched: " + route.getId()); } return route; }); /* TODO: trace logging if (logger.isTraceEnabled()) { logger.trace("RouteDefinition did not match: " + routeDefinition.getId()); }*/ } //......}复制代码

这个类名有点绕，如同注释里头说的，它是一个routeLocator，从routeDefinitionLocator获取Route信息

这里注入的routeDefinitionLocator是CompositeRouteDefinitionLocator，它组合了InMemoryRouteDefinitionRepository、PropertiesRouteDefinitionLocator、DiscoveryClientRouteDefinitionLocator三个RouteDefinitionLocator。

PropertiesRouteDefinitionLocator是直接使用GatewayProperties的getRoutes()获取，其是通过spring.cloud.gateway.routes配置得来。

convertToRoute

private Route convertToRoute(RouteDefinition routeDefinition) {		Predicate
    
      predicate = combinePredicates(routeDefinition);		List
     
       gatewayFilters = getFilters(routeDefinition);		return Route.builder(routeDefinition)				.predicate(predicate)				.replaceFilters(gatewayFilters)				.build();	}复制代码

RouteDefinitionRouteLocator的getRoutes方法，从routeDefinitionLocator.getRouteDefinitions()，然后使用convertToRoute方法进行转换，该方法主要用到了combinePredicates、getFilters两个方法

combinePredicates

private Predicate
    
      combinePredicates(RouteDefinition routeDefinition) {		List
     
       predicates = routeDefinition.getPredicates();		Predicate
      
        predicate = lookup(routeDefinition, predicates.get(0));		for (PredicateDefinition andPredicate : predicates.subList(1, predicates.size())) {			Predicate
       
         found = lookup(routeDefinition, andPredicate);			predicate = predicate.and(found);		}		return predicate;	}	private Predicate
        
          lookup(RouteDefinition route, PredicateDefinition predicate) {		RoutePredicateFactory

这里利用工厂方法，根据config去apply出来Predicate 而combinePredicates主要是对找出来的predicate进行and操作

getFilters

private List
    
      getFilters(RouteDefinition routeDefinition) {		List
     
       filters = new ArrayList<>();		//TODO: support option to apply defaults after route specific filters?		if (!this.gatewayProperties.getDefaultFilters().isEmpty()) {			filters.addAll(loadGatewayFilters("defaultFilters",					this.gatewayProperties.getDefaultFilters()));		}		if (!routeDefinition.getFilters().isEmpty()) {			filters.addAll(loadGatewayFilters(routeDefinition.getId(), routeDefinition.getFilters()));		}		AnnotationAwareOrderComparator.sort(filters);		return filters;	}	private List
      
        loadGatewayFilters(String id, List
       
         filterDefinitions) {		List
        
          filters = filterDefinitions.stream()				.map(definition -> {					GatewayFilterFactory factory = this.gatewayFilterFactories.get(definition.getName());					if (factory == null) {                        throw new IllegalArgumentException("Unable to find GatewayFilterFactory with name " + definition.getName());					}					Map
         
           args = definition.getArgs(); if (logger.isDebugEnabled()) { logger.debug("RouteDefinition " + id + " applying filter " + args + " to " + definition.getName()); } Map
          
            properties = factory.shortcutType().normalize(args, factory, this.parser, this.beanFactory); Object configuration = factory.newConfig(); ConfigurationUtils.bind(configuration, properties, factory.shortcutFieldPrefix(), definition.getName(), validator); GatewayFilter gatewayFilter = factory.apply(configuration); if (this.publisher != null) { this.publisher.publishEvent(new FilterArgsEvent(this, id, properties)); } return gatewayFilter; }) .collect(Collectors.toList()); ArrayList
           
             ordered = new ArrayList<>(filters.size()); for (int i = 0; i < filters.size(); i++) { GatewayFilter gatewayFilter = filters.get(i); if (gatewayFilter instanceof Ordered) { ordered.add(gatewayFilter); } else { ordered.add(new OrderedGatewayFilter(gatewayFilter, i + 1)); } } return ordered; }复制代码

getFilters主要是利用loadGatewayFilters获取filter，返回使用AnnotationAwareOrderComparator进行排序 loadGatewayFilters也是利用工厂方法，使用GatewayFilterFactory根据config去apply出来具体的GatewayFilter实例

小结

RouteLocator接口用于获取路由信息，其有三个实现类

RouteDefinitionRouteLocator

CompositeRouteLocator

CachingRouteLocator

最终使用的是CachingRouteLocator，它包装了CompositeRouteLocator，而CompositeRouteLocator则组合了RouteDefinitionRouteLocator。

RouteDefinitionRouteLocator与RouteDefinitionLocator比较容易混淆，前者是一个RouteLocator，后者是一个RouteDefinitionLocator，前者的RouteDefinitionRouteLocator主要从后者获取路由定义信息。

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