Spring Cloud Gateway 源码解析（2） —— 路由
2024-04-27 05:16:10
目录
基本组件
路由定位器（RouteDefinitionLocator ）
路由定义（RouteDefinition）
PredicateDefinition
FilterDefinition
CompositeRouteDefinitionLocator
路由定位器 （RouteLocator）
Route
RouteDefinitionLocator解析
PropertiesRouteDefinitionLocator
GatewayProperties
RouteDefinitionRepository
RouteDefinitionWriter
InMemoryRouteDefinitionRepository
自定义RouteDefinitionRepository
DiscoveryClientRouteDefinitionLocator
RouteLocator解析
RouteLocator
CompositeRouteLocator
CachingRouteLocator
RouteDefinitionRouteLocator
构造函数
获得 Route
自定义 RouteLocator
基本组件
路由定位器（RouteDefinitionLocator ）
RouteDefinitionLocator 负责读取路由配置（RouteDefinition ），Gateway实现了多种Locator。
public interface RouteDefinitionLocator {Flux<RouteDefinition> getRouteDefinitions();
}
- PropertiesRouteDefinitionLocator
从配置文件( 例如，YML / Properties 等 ) 读取
- RouteDefinitionRepository
从存储器( 例如，内存 / Redis / MySQL 等 )读取。
- DiscoveryClientRouteDefinitionLocator
从注册中心( 例如，Eureka / Consul / Zookeeper / Etcd 等 )读取。
- CompositeRouteDefinitionLocator
组合多种 RouteDefinitionLocator 的实现，为 RouteDefinitionRouteLocator 提供统一入口。
- CachingRouteDefinitionLocator
已经被 CachingRouteLocator 取代。
路由定义（RouteDefinition）
@Validated
public class RouteDefinition {@NotEmptyprivate String id = UUID.randomUUID().toString();@NotEmpty@Validprivate List<PredicateDefinition> predicates = new ArrayList<>();@Validprivate List<FilterDefinition> filters = new ArrayList<>();@NotNullprivate URI uri;private int order = 0;
}id属性，ID 编号，唯一。predicates属性，谓语定义数组。请求通过predicates判断是否匹配。在 Route 里，PredicateDefinition 转换成 Predicate 。filters属性，过滤器定义数组。在 Route 里，FilterDefinition 转换成 GatewayFilter 。uri属性，路由向的 URI 。order属性，顺序。当请求匹配到多个路由时，使用顺序小的。
RouteDefinition 提供 text 字符串创建对象（yaml配置中属性值），格式为：
${id}=${uri},${predicates[0]},${predicates[1]}...${predicates[n]}
public RouteDefinition(String text) ;PredicateDefinition
@Validated
public class PredicateDefinition {/*** 谓语定义名字，通过 name 对应到 org.springframework.cloud.gateway.handler.predicate.RoutePredicateFactory 的实现类*/@NotNullprivate String name;/*** 参数数组*/private Map<String, String> args = new LinkedHashMap<>();
}提供了构造函数：
/*** 根据 text 创建 PredicateDefinition** @param text 格式 ${name}=${args[0]},${args[1]}...${args[n]}* 例如 Host=iocoder.cn*/
public PredicateDefinition(String text);FilterDefinition
@Validated
public class FilterDefinition {/*** 过滤器定义名字。通过 name 对应到 org.springframework.cloud.gateway.filter.factory.GatewayFilterFactory 的实现类*/@NotNullprivate String name;/*** 参数数组*/private Map<String, String> args = new LinkedHashMap<>();
}提供了构造函数：
/*** 根据 text 创建 FilterDefinition** @param text 格式 ${name}=${args[0]},${args[1]}...${args[n]}* 例如 AddRequestParameter=foo, bar*/
public FilterDefinition(String text);CompositeRouteDefinitionLocator
组合多种 RouteDefinitionLocator 的实现，为 RouteDefinitionRouteLocator 提供统一入口
@Overridepublic Flux<RouteDefinition> getRouteDefinitions() {return this.delegates.flatMap(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);});}
路由定位器 （RouteLocator）
- RouteLocator 可以直接自定义路由(
org.springframework.cloud.gateway.route.Route) ，也可以通过 RouteDefinitionRouteLocator 获取 RouteDefinition ，并转换成 Route 。 - RoutePredicateHandlerMapping 使用 RouteLocator 获得 Route 信息。
Route
Route与RouteDefinition结构相似。同时实现了Order接口。
public class Route implements Ordered {/*** 路由编号*/private final String id;/*** 路由向的 URI*/private final URI uri;/*** 顺序*/private final int order;/*** 谓语数组*/private final Predicate<ServerWebExchange> predicate;/*** 过滤器数组*/private final List<GatewayFilter> gatewayFilters;
}Route 内置 Builder 类，根据RouteDefinition 构造对象。predicate / gatewayFilters 属性，需要调用 Builder 相关方法进行设置
public static Builder builder(RouteDefinition routeDefinition) {// @formatter:offreturn new Builder().id(routeDefinition.getId()).uri(routeDefinition.getUri()).order(routeDefinition.getOrder()).metadata(routeDefinition.getMetadata());// @formatter:on}RouteDefinitionLocator解析
PropertiesRouteDefinitionLocator
从GatewayProperties 中获取路由信息。
public class PropertiesRouteDefinitionLocator implements RouteDefinitionLocator {private final GatewayProperties properties;public PropertiesRouteDefinitionLocator(GatewayProperties properties) {this.properties = properties;}@Overridepublic Flux<RouteDefinition> getRouteDefinitions() {return Flux.fromIterable(this.properties.getRoutes());}}GatewayProperties
GatewayProperties ，从配置文件读取 ：
- 路由配置
通过 spring.cloud.gateway.routes 配置
- 默认过滤器配置。当 RouteDefinition => Route 时，会将过滤器配置添加到每个 Route 。
通过 spring.cloud.gateway.default-filters 配置
@ConfigurationProperties("spring.cloud.gateway")
@Validated
public class GatewayProperties {/*** List of Routes.*/@NotNull@Validprivate List<RouteDefinition> routes = new ArrayList<>();/*** List of filter definitions that are applied to every route.*/private List<FilterDefinition> defaultFilters = new ArrayList<>();
}RouteDefinitionRepository
public interface RouteDefinitionRepositoryextends RouteDefinitionLocator, RouteDefinitionWriter {}类继承关系如下：
RouteDefinitionWriter
RouteDefinitionWriter ，路由配置写入接口。该接口定义了保存与删除两个方法
public interface RouteDefinitionWriter {/*** 保存路由配置** @param route 路由配置* @return Mono<Void>*/Mono<Void> save(Mono<RouteDefinition> route);/*** 删除路由配置** @param routeId 路由编号* @return Mono<Void>*/Mono<Void> delete(Mono<String> routeId);
}InMemoryRouteDefinitionRepository
基于内存为存储器的 RouteDefinitionLocator
public class InMemoryRouteDefinitionRepository implements RouteDefinitionRepository {private final Map<String, RouteDefinition> routes = synchronizedMap(new LinkedHashMap<String, RouteDefinition>());@Overridepublic Flux<RouteDefinition> getRouteDefinitions() {return Flux.fromIterable(routes.values());}
}路由信息构造：
@Overridepublic Mono<Void> save(Mono<RouteDefinition> route) {return route.flatMap(r -> {if (StringUtils.isEmpty(r.getId())) {return Mono.error(new IllegalArgumentException("id may not be empty"));}routes.put(r.getId(), r);return Mono.empty();});}@Overridepublic Mono<Void> delete(Mono<String> routeId) {return routeId.flatMap(id -> {if (routes.containsKey(id)) {routes.remove(id);return Mono.empty();}return Mono.defer(() -> Mono.error(new NotFoundException("RouteDefinition not found: " + routeId)));});}自定义RouteDefinitionRepository
可以自定义RouteDefinitionRepository，如果没有自定义，才使用内存存储。
// GatewayAutoConfiguration.java
@Bean
@ConditionalOnMissingBean(RouteDefinitionRepository.class)
public InMemoryRouteDefinitionRepository inMemoryRouteDefinitionRepository() {return new InMemoryRouteDefinitionRepository();
}DiscoveryClientRouteDefinitionLocator
DiscoveryClientRouteDefinitionLocator 通过调用 org.springframework.cloud.client.discovery.DiscoveryClient 获取注册在注册中心的服务列表，生成对应的 RouteDefinition 数组。
public class DiscoveryClientRouteDefinitionLocator implements RouteDefinitionLocator {private final DiscoveryLocatorProperties properties;private final String routeIdPrefix;private final SimpleEvaluationContext evalCtxt;private Flux<List<ServiceInstance>> serviceInstances;}
@Overridepublic Flux<RouteDefinition> getRouteDefinitions() {SpelExpressionParser parser = new SpelExpressionParser();Expression includeExpr = parser.parseExpression(properties.getIncludeExpression());Expression urlExpr = parser.parseExpression(properties.getUrlExpression());//构造服务实例是否可用predicate。Predicate<ServiceInstance> includePredicate;if (properties.getIncludeExpression() == null|| "true".equalsIgnoreCase(properties.getIncludeExpression())) {includePredicate = instance -> true;}else {includePredicate = instance -> {Boolean include = includeExpr.getValue(evalCtxt, instance, Boolean.class);if (include == null) {return false;}return include;};}return serviceInstances.filter(instances -> !instances.isEmpty())//返回可用实例.map(instances -> instances.get(0)).filter(includePredicate).map(instance -> {
//构建definitionRouteDefinition routeDefinition = buildRouteDefinition(urlExpr,instance);final ServiceInstance instanceForEval = new DelegatingServiceInstance(instance, properties);
//拷贝PredicateDefinition for (PredicateDefinition original : this.properties.getPredicates()) {PredicateDefinition predicate = new PredicateDefinition();predicate.setName(original.getName());for (Map.Entry<String, String> entry : original.getArgs().entrySet()) {
//计算表达式值。String value = getValueFromExpr(evalCtxt, parser,instanceForEval, entry);predicate.addArg(entry.getKey(), value);}routeDefinition.getPredicates().add(predicate);}
//拷贝FilterDefinition for (FilterDefinition original : this.properties.getFilters()) {FilterDefinition filter = new FilterDefinition();filter.setName(original.getName());for (Map.Entry<String, String> entry : original.getArgs().entrySet()) {
//计算表达式值。String value = getValueFromExpr(evalCtxt, parser,instanceForEval, entry);filter.addArg(entry.getKey(), value);}routeDefinition.getFilters().add(filter);}return routeDefinition;});}
RouteLocator解析
RouteLocator
路由定位器接口，定义获得路由数组的方法
public interface RouteLocator {Flux<Route> getRoutes();
}
CompositeRouteLocator
组合多种 RouteLocator 的实现类，为 RoutePredicateHandlerMapping 提供统一入口访问路由
public class CompositeRouteLocator implements RouteLocator {private final Flux<RouteLocator> delegates;public CompositeRouteLocator(Flux<RouteLocator> delegates) {this.delegates = delegates;}@Overridepublic Flux<Route> getRoutes() {return this.delegates.flatMap(RouteLocator::getRoutes);}}CachingRouteLocator
CachingRouteLocator ，缓存路由的 RouteLocator 实现类。RoutePredicateHandlerMapping 调用 CachingRouteLocator 的 RouteLocator#getRoutes() 方法，获取路由。
public class CachingRouteLocatorimplements Ordered, RouteLocator, ApplicationListener<RefreshRoutesEvent> {private static final String CACHE_KEY = "routes";private final RouteLocator delegate;private final Flux<Route> routes;private final Map<String, List> cache = new ConcurrentHashMap<>();public CachingRouteLocator(RouteLocator delegate) {this.delegate = delegate;routes = CacheFlux.lookup(cache, CACHE_KEY, Route.class).onCacheMissResume(this::fetch);}
}RouteDefinitionRouteLocator
RouteDefinitionRouteLocator ，基于 RouteDefinitionLocator 的 RouteLocator 实现类。RouteDefinitionRouteLocator 从 RouteDefinitionLocator 获取 RouteDefinition ，转换成 Route
public class RouteDefinitionRouteLocatorimplements RouteLocator, BeanFactoryAware, ApplicationEventPublisherAware {/*** Default filters name.*/public static final String DEFAULT_FILTERS = "defaultFilters";protected final Log logger = LogFactory.getLog(getClass());private final RouteDefinitionLocator routeDefinitionLocator;private final ConfigurationService configurationService;private final Map<String, RoutePredicateFactory> predicates = new LinkedHashMap<>();private final Map<String, GatewayFilterFactory> gatewayFilterFactories = new HashMap<>();private final GatewayProperties gatewayProperties;
}构造函数
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;}获得 Route
@Overridepublic Flux<Route> getRoutes() {//routeDefinitionLocator获取RouteDefinitions，转换成RouteFlux<Route> routes = this.routeDefinitionLocator.getRouteDefinitions().map(this::convertToRoute);//错误是否抛出异常if (!gatewayProperties.isFailOnRouteDefinitionError()) {// instead of letting error bubble up, continueroutes = routes.onErrorContinue((error, obj) -> {if (logger.isWarnEnabled()) {logger.warn("RouteDefinition id " + ((RouteDefinition) obj).getId()+ " will be ignored. Definition has invalid configs, "+ error.getMessage());}});}return routes.map(route -> {if (logger.isDebugEnabled()) {logger.debug("RouteDefinition matched: " + route.getId());}return route;});}//合并predicate，合并filters，构造一个route。private Route convertToRoute(RouteDefinition routeDefinition) {AsyncPredicate<ServerWebExchange> predicate = combinePredicates(routeDefinition);List<GatewayFilter> gatewayFilters = getFilters(routeDefinition);return Route.async(routeDefinition).asyncPredicate(predicate).replaceFilters(gatewayFilters).build();}
自定义 RouteLocator
RouteLocatorBuilder用于自定义RouteLocator
public class RouteLocatorBuilder { public Builder routes() {return new Builder(context);}
}public static class Builder {private List<Route.AsyncBuilder> routes = new ArrayList<>();private ConfigurableApplicationContext context;public Builder(ConfigurableApplicationContext context) {this.context = context;}
}- RouteSpec：route builder。
- UriSpec：可以添加一个Uri
- PredicateSpec：可以应用到一个Uri的Predicate。
- BooleanOpSpec：逻辑操作Predicate。
- GatewayFilterSpec：GatewayFilter
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