007-spring cloud gateway-GatewayAutoConfiguration核心配置-RouteDefinition初始化加载

一、RouteDefinitionLocator

　　在Spring-Cloud-Gateway的GatewayAutoConfiguration初始化加载中会加载RouteDefinitionLocator（路由定义信息加载器）信息。

//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));
    }

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
*/ public interface RouteDefinitionLocator { /** * 获取RouteDefinition */ Flux<RouteDefinition> getRouteDefinitions(); }

RouteDefinitionLocator接口只有一个方法getRouteDefinitions，此方法获取RouteDefinition的核心方法，返回Flux<RouteDefinition>

1.1、PropertiesRouteDefinitionLocator--从配置文件读取定义定位器

// 从Properties（GatewayProperties）中加载RouteDefinition信息
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());
    }
}

• GatewayProperties 在GatewayProperties初始化加载，参看：
• Flux 响应式编程

1.2、CachingRouteDefinitionLocator--缓存路由定义定位器

// RouteDefinitionLocator 包装实现类，实现了路由定义的本地缓存功能
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());

    }
}

1.3、DiscoveryClientRouteDefinitionLocator--配置中心路由定义定位器

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
    @Override
    public Flux<RouteDefinition> getRouteDefinitions() {
     //...
    }
}

1.4、CompositeRouteDefinitionLocator--各个定位器合并提供统一的getRouteDefinitions方法入口

// 组合多个 RouteDefinitionLocator 的实现，为 routeDefinitions提供统一入口
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);
    }
}

综合上述

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

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

其中GatewayDiscoveryClientAutoConfiguration如下

@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);
    }
}