Spring-Cloud-Gateway源码分析系列 | Spring-Cloud-Gateway之RouteDefinition初始化加载

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RouteDefinition路由定义,Spring-Cloud-Gateway通过RouteDefinition来转换生成具体的路由信息。RouteDefinition的信息是怎么加载初始化到网关系统中的,接下来阅读Spring-Cloud-Gateway的RouteDefinitionLocator(路由定义信息加载器)接口,学习RouteDefinition初始化加载

首先查看RouteDefinitionLocator源码

    /**
     * 路由定义信息的定位器,
     * 负责读取路由配置( org.springframework.cloud.gateway.route.RouteDefinition
     * 子类实现类
     *  1.CachingRouteDefinitionLocator -RouteDefinitionLocator包装类, 缓存目标RouteDefinitionLocator 为routeDefinitions提供缓存功能
     *  2.CompositeRouteDefinitionLocator -RouteDefinitionLocator包装类,组合多种 RouteDefinitionLocator 的实现,为 routeDefinitions提供统一入口
     *  3.PropertiesRouteDefinitionLocator-从配置文件(GatewayProperties 例如,YML / Properties 等 ) 读取RouteDefinition
     *  4.DiscoveryClientRouteDefinitionLocator-从注册中心( 例如,Eureka / Consul / Zookeeper / Etcd 等 )读取RouteDefinition
     *  5.RouteDefinitionRepository-从存储器( 例如,内存 / Redis / MySQL 等 )读取RouteDefinition
     * @author Spencer Gibb
     */
    public interface RouteDefinitionLocator {

        /**
         * 获取RouteDefinition
         * @return
         */
        Flux<RouteDefinition> getRouteDefinitions();
    }

RouteDefinitionLocator接口有且仅有一个方法getRouteDefinitions,此方法获取RouteDefinition的核心方法,返回Flux

RouteDefinitionLocator 类图如下:

    graph TD
    RouteDefinitionLocator-->CachingRouteDefinitionLocator
    RouteDefinitionLocator-->CompositeRouteDefinitionLocator
    RouteDefinitionLocator-->PropertiesRouteDefinitionLocator
    RouteDefinitionLocator-->DiscoveryClientRouteDefinitionLocator
    RouteDefinitionLocator-->RouteDefinitionRepository

子类功能描述:

  • CachingRouteDefinitionLocator:RouteDefinitionLocator包装类, 缓存目标RouteDefinitionLocator 为routeDefinitions提供缓存功能
  • CompositeRouteDefinitionLocator -RouteDefinitionLocator包装类,组合多种 RouteDefinitionLocator 的实现,为 routeDefinitions提供统一入口
  • PropertiesRouteDefinitionLocator-从配置文件(GatewayProperties 例如,YML / Properties 等 ) 读取RouteDefinition
  • RouteDefinitionRepository-从存储器( 例如,内存 / Redis / MySQL 等 )读取RouteDefinition
  • DiscoveryClientRouteDefinitionLocator-从注册中心( 例如,Eureka / Consul / Zookeeper / Etcd 等
    接下来详细看子类的源码分析主要实现功能
  • PropertiesRouteDefinitionLocator
    /**
     * 从Properties(GatewayProperties)中加载RouteDefinition信息
     * @author Spencer Gibb
     */
    public class PropertiesRouteDefinitionLocator implements RouteDefinitionLocator {

        /**
         * 从appliccation.yml中解析前缀为spring.cloud.gateway的配置
         */
        private final GatewayProperties properties;

        public PropertiesRouteDefinitionLocator(GatewayProperties properties) {
            this.properties = properties;
        }

        @Override
        public Flux<RouteDefinition> getRouteDefinitions() {
            return Flux.fromIterable(this.properties.getRoutes());
        }
    }

PropertiesRouteDefinitionLocator很简单从GatewayProperties实例获取RouteDefinition信息

    - GatewayProperties 在GatewayProperties初始化加载文中已详细描述
    - Flux 响应式编程
  • CachingRouteDefinitionLocator

    /**
     * RouteDefinitionLocator 包装实现类,实现了路由定义的本地缓存功能
     * @author Spencer Gibb
     */
    public class CachingRouteDefinitionLocator implements RouteDefinitionLocator {

        /**
         * 实际路由定义定位器
         */
        private final RouteDefinitionLocator delegate;

        private final Flux<RouteDefinition> routeDefinitions;
        /**
         * 路由定义的本地缓存
         */
        private final Map<String, List> cache = new HashMap<>();

        public CachingRouteDefinitionLocator(RouteDefinitionLocator delegate) {
            this.delegate = delegate;
            routeDefinitions = CacheFlux.lookup(cache, "routeDefs", RouteDefinition.class)
                    .onCacheMissResume(() -> this.delegate.getRouteDefinitions());

        }

    }   

RouteDefinitionLocator包装类,缓存目标RouteDefinitionLocator 为routeDefinitions提供缓存功能

  • DiscoveryClientRouteDefinitionLocator
    public class DiscoveryClientRouteDefinitionLocator implements RouteDefinitionLocator {
        /**
         * 注册中心客户端
         */
        private final DiscoveryClient discoveryClient;
        /**
         * 本地配置信息
         */
        private final DiscoveryLocatorProperties properties;
        /**
         * 路由ID前缀
         */
        private final String routeIdPrefix;

        public DiscoveryClientRouteDefinitionLocator(DiscoveryClient discoveryClient, DiscoveryLocatorProperties properties) {
            this.discoveryClient = discoveryClient;
            this.properties = properties;
            if (StringUtils.hasText(properties.getRouteIdPrefix())) {
                this.routeIdPrefix = properties.getRouteIdPrefix();
            } else {
                this.routeIdPrefix = this.discoveryClient.getClass().getSimpleName() + "_";
            }
        }

        /**
         * 通过注册中心查找服务组装路由定义信息
         * @return
         */
        @Override
        public Flux<RouteDefinition> getRouteDefinitions() {
         ...代码在根据注册中心查找路由详细解析

        }
    }   

DiscoveryClientRouteDefinitionLocator通过调用 DiscoveryClient 获取注册在注册中心的服务列表,生成对应的 RouteDefinition 数组

  • CompositeRouteDefinitionLocator
    /**
     * 组合多个 RouteDefinitionLocator 的实现,为 routeDefinitions提供统一入口
     * @author Spencer Gibb
     */
    public class CompositeRouteDefinitionLocator implements RouteDefinitionLocator {

        /**
         * 所有路由定义定位器实例集合
         */
        private final Flux<RouteDefinitionLocator> delegates;

        public CompositeRouteDefinitionLocator(Flux<RouteDefinitionLocator> delegates) {
            this.delegates = delegates;
        }

        @Override
        public Flux<RouteDefinition> getRouteDefinitions() {
            //将各个RouteDefinitionLocator的getRouteDefinitions合并返回统一的Flux<RouteDefinition>
            return this.delegates.flatMap(RouteDefinitionLocator::getRouteDefinitions);
        }
    }

CompositeRouteDefinitionLocator 的主要作用就是将各个定位器合并提供统一的getRouteDefinitions方法入口

通过子类实现具体功能可以很清晰的看到定位器加载RouteDefinition整个流程

    graph TD
    PropertiesRouteDefinitionLocator-->|配置文件加载初始化| CompositeRouteDefinitionLocator
    RouteDefinitionRepository-->|存储器中加载初始化| CompositeRouteDefinitionLocator
    DiscoveryClientRouteDefinitionLocator-->|注册中心加载初始化| CompositeRouteDefinitionLocator

最终提供通过CompositeRouteDefinitionLocator提供统一的
getRouteDefinitions方法

RouteDefinitionLocator实例的初始化在GatewayAutoConfiguration中已经完成

GatewayDiscoveryClientAutoConfiguration


    @Configuration
    @ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
    @AutoConfigureBefore(GatewayAutoConfiguration.class)
    @ConditionalOnClass({DispatcherHandler.class, DiscoveryClient.class})
    @EnableConfigurationProperties
    public class GatewayDiscoveryClientAutoConfiguration {

        //初始化注册中心路由定义定位器
        @Bean
        @ConditionalOnBean(DiscoveryClient.class)
        @ConditionalOnProperty(name = "spring.cloud.gateway.discovery.locator.enabled")
        public DiscoveryClientRouteDefinitionLocator discoveryClientRouteDefinitionLocator(
                DiscoveryClient discoveryClient, DiscoveryLocatorProperties properties) {
            return new DiscoveryClientRouteDefinitionLocator(discoveryClient, properties);
        }

GatewayAutoConfiguration

       //初始化配置路由定义加载器
        @Bean
        @ConditionalOnMissingBean
        public PropertiesRouteDefinitionLocator propertiesRouteDefinitionLocator(GatewayProperties properties) {
            return new PropertiesRouteDefinitionLocator(properties);
        }

        //初始化存储路由定义加载器
        @Bean
        @ConditionalOnMissingBean(RouteDefinitionRepository.class)
        public InMemoryRouteDefinitionRepository inMemoryRouteDefinitionRepository() {
            return new InMemoryRouteDefinitionRepository();
        }

         //初始化聚合路由定义加载器
        @Bean
        @Primary
        public RouteDefinitionLocator routeDefinitionLocator(List<RouteDefinitionLocator> routeDefinitionLocators) {
            return new CompositeRouteDefinitionLocator(Flux.fromIterable(routeDefinitionLocators));
        }

在Spring-Cloud-Gateway初始化完成后需要的路由定义加载器已全部实例化完成,这样就为路由的加载创建完成了必要的条件。

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