SpringCloudGateway小记

目录标题

• GateWayProperties
• List<FilterDefinition> defaultFilters
• List routes
• Route
• 路由工厂
• CachingRouteLocator 实现
• 基础 RouteLocator 定义
• Gateway 总路由

GateWayProperties

public class GatewayProperties {
	/**
	 * List of Routes.
	 */
	private List<RouteDefinition> routes = new ArrayList<>();

	/**
	 * List of filter definitions that are applied to every route.
	 */
	private List<FilterDefinition> defaultFilters = new ArrayList<>();

	private List<MediaType> streamingMediaTypes = Arrays
			.asList(MediaType.TEXT_EVENT_STREAM, MediaType.APPLICATION_STREAM_JSON);

对应配置文件中：

spring:
  cloud:
    gateway:
      default-filters:
      - PrefixPath=/httpbin
      - AddResponseHeader=X-Response-Default-Foo, Default-Bar
      routes:
        - id: websocket_test
        uri: ws://localhost:9000
        order: 9000
        predicates:
        - Path=/echo
      # =====================================
      - id: default_path_to_httpbin
        uri: ${test.uri}
        order: 10000
        predicates:
        - Path=/**

List<FilterDefinition> defaultFilters

org.springframework.cloud.gateway.filter.FilterDefinition

public class FilterDefinition {
	private String name;
	private Map<String, String> args = new LinkedHashMap<>();
	public FilterDefinition(String text) {
		int eqIdx = text.indexOf('=');
		if (eqIdx <= 0) {
			setName(text);
			return;
		}
		setName(text.substring(0, eqIdx));

		String[] args = tokenizeToStringArray(text.substring(eqIdx + 1), ",");

		for (int i = 0; i < args.length; i++) {
			this.args.put(NameUtils.generateName(i), args[i]);
		}
	}
	
-------------
public final class NameUtils {
	/**
	 * Generated name prefix.
	 */
	public static final String GENERATED_NAME_PREFIX = "_genkey_";

	public static String generateName(int i) {
		return GENERATED_NAME_PREFIX + i;
	}

配置DEMO

spring: 
  cloud:
    gateway:
      default-filters:
      - PrefixPath=/httpbin
      - AddResponseHeader=X-Response-Default-Foo, Default-Bar

构造函数 参数只有一个字符串
name=value1,value2,value3,…
故每个FilterDefinition 的name与args 的Value 为外部配置,args 的Key 为自动生成 规则为 _genkey_+序号

List routes

org.springframework.cloud.gateway.route.RouteDefinition

public class RouteDefinition {
	private String id;
	private List<PredicateDefinition> predicates = new ArrayList<>();
	private List<FilterDefinition> filters = new ArrayList<>();
	private URI uri;
	private Map<String, Object> metadata = new HashMap<>();
	private int order = 0;
	public RouteDefinition() {
	}
	public RouteDefinition(String text) {
		int eqIdx = text.indexOf('=');
		if (eqIdx <= 0) {
			throw new ValidationException("Unable to parse RouteDefinition text '" + text
					+ "'" + ", must be of the form name=value");
		}
		setId(text.substring(0, eqIdx));
		String[] args = tokenizeToStringArray(text.substring(eqIdx + 1), ",");
		setUri(URI.create(args[0]));
		for (int i = 1; i < args.length; i++) {
			this.predicates.add(new PredicateDefinition(args[i]));
		}
	}

配置DEMO

spring:
  cloud:
    gateway:
      routes:
      - id: websocket_test
        uri: ws://localhost:9000
        order: 9000
        predicates:
        - Path=/echo
      # =====================================
      - id: default_path_to_httpbin
        uri: ${test.uri}
        order: 10000
        predicates:
        - Path=/**

List predicates

配置匹配表达式

public class PredicateDefinition {
	private String name;
	private Map<String, String> args = new LinkedHashMap<>();
	public PredicateDefinition() {
	}
	public PredicateDefinition(String text) {
		int eqIdx = text.indexOf('=');
		if (eqIdx <= 0) {
			throw new ValidationException("Unable to parse PredicateDefinition text '"
					+ text + "'" + ", must be of the form name=value");
		}
		setName(text.substring(0, eqIdx));
		String[] args = tokenizeToStringArray(text.substring(eqIdx + 1), ",");
		for (int i = 0; i < args.length; i++) {
			this.args.put(NameUtils.generateName(i), args[i]);
		}
	}

构造函数 参数只有一个字符串
name=value1,value2,value3,…
故每个PredicateDefinition 的name与args 的Value 为外部配置,args 的Key 为自动生成 规则为 _genkey_+序号

Route

org.springframework.cloud.gateway.route.Route
路由的基础单位
业务代码：

org.springframework.cloud.gateway.handler.RoutePredicateHandlerMapping#lookupRoute

public class Route implements Ordered {

	private final String id;

	private final URI uri;

	private final int order;
	/**
	 * 本路由的匹配规则
	 */
	private final AsyncPredicate<ServerWebExchange> predicate;
	/**
	 * 需要执行的过滤器
	 */
	private final List<GatewayFilter> gatewayFilters;

	private final Map<String, Object> metadata;

路由工厂

org.springframework.cloud.gateway.route.RouteLocator

/**
 * @author Spencer Gibb
 */
// TODO: rename to Routes?
public interface RouteLocator {

	Flux<Route> getRoutes();

}

默认的 SpringCloudGateWay 的 路由工厂使用

org.springframework.cloud.gateway.route.CachingRouteLocator

CachingRouteLocator 实现

org.springframework.cloud.gateway.config.GatewayAutoConfiguration#cachedCompositeRouteLocator

	public CachingRouteLocator(RouteLocator delegate) {
		this.delegate = delegate;
		routes = CacheFlux.lookup(cache, CACHE_KEY, Route.class)
				.onCacheMissResume(this::fetch);
	}

才用组合委托设计实现

基础 RouteLocator 定义

Bean 定义模式

 @Bean
    open fun additionalRouteLocator(builder: RouteLocatorBuilder) = builder.routes {
        route(id = "test-kotlin") {
            host("kotlin.abc.org") and path("/image/png")
            filters {
                prefixPath("/httpbin")
                addResponseHeader("X-TestHeader", "foobar")
            }
            uri(uri)
        }
    }

@Bean
public RouteLocator routes(RouteLocatorBuilder builder) {
    return builder.routes()
        .route("circuitbreaker_route", r -> r.path("/consumingServiceEndpoint")
            .filters(f -> f.circuitBreaker(c -> c.name("myCircuitBreaker").fallbackUri("forward:/inCaseOfFailureUseThis").addStatusCode("INTERNAL_SERVER_ERROR"))
                .rewritePath("/consumingServiceEndpoint", "/backingServiceEndpoint")).uri("lb://backing-service:8088")
        .build();
}

使用YAML 配置文件

spring:
  cloud:
    gateway:
      default-filters:
      - PrefixPath=/
      - AddResponseHeader=X-Response-Default-Foo, Default-Bar

      routes:
      - id: websocket_test
        uri: ws://localhost:9000
        order: 9000
        predicates:
        - Path=/echo

配置文件读取上GateWayProperties

配置文件实例化 RouteLocator

RouteDefinition 定义 RouteLocator

	public List<RouteDefinition> getRoutes() {
		return routes;
	}

org.springframework.cloud.gateway.config.PropertiesRouteDefinitionLocator

public class PropertiesRouteDefinitionLocator implements RouteDefinitionLocator {

	private final GatewayProperties properties;

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

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

}

在此加载 RouteLocator 的定义文件 (RouteDefinition)

org.springframework.cloud.gateway.route.RouteDefinitionRouteLocator#getRoutes

	@Override
	public Flux<Route> getRoutes() {
		Flux<Route> routes = this.routeDefinitionLocator.getRouteDefinitions()
				.map(this::convertToRoute);

	private Route convertToRoute(RouteDefinition routeDefinition) {
		AsyncPredicate<ServerWebExchange> predicate = combinePredicates(routeDefinition);
		List<GatewayFilter> gatewayFilters = getFilters(routeDefinition);

		return Route.async(routeDefinition).asyncPredicate(predicate)
				.replaceFilters(gatewayFilters).build();
	}

RouteDefinition 转换为 Router

Gateway 总路由

GateWay 映射

org.springframework.cloud.gateway.handler.RoutePredicateHandlerMapping

@Override
	protected Mono<?> getHandlerInternal(ServerWebExchange exchange) {
		// don't handle requests on management port if set and different than server port
		if (this.managementPortType == DIFFERENT && this.managementPort != null
				&& exchange.getRequest().getURI().getPort() == this.managementPort) {
			return Mono.empty();
		}
		exchange.getAttributes().put(GATEWAY_HANDLER_MAPPER_ATTR, getSimpleName());

		return lookupRoute(exchange)
				// .log("route-predicate-handler-mapping", Level.FINER) //name this
				.flatMap((Function<Route, Mono<?>>) r -> {
					exchange.getAttributes().remove(GATEWAY_PREDICATE_ROUTE_ATTR);
					if (logger.isDebugEnabled()) {
						logger.debug(
								"Mapping [" + getExchangeDesc(exchange) + "] to " + r);
					}

					exchange.getAttributes().put(GATEWAY_ROUTE_ATTR, r);
					return Mono.just(webHandler);
				}).switchIfEmpty(Mono.empty().then(Mono.fromRunnable(() -> {
					exchange.getAttributes().remove(GATEWAY_PREDICATE_ROUTE_ATTR);
					if (logger.isTraceEnabled()) {
						logger.trace("No RouteDefinition found for ["
								+ getExchangeDesc(exchange) + "]");
					}
				})));
	}

路由转发与过滤器

org.springframework.web.reactive.DispatcherHandler#handle
使用SpringWebFlux

	@Override
	public Mono<Void> handle(ServerWebExchange exchange) {
		if (this.handlerMappings == null) {
			return createNotFoundError();
		}
		return Flux.fromIterable(this.handlerMappings)
				.concatMap(mapping -> mapping.getHandler(exchange))
				.next()
				.switchIfEmpty(createNotFoundError())
				.flatMap(handler -> invokeHandler(exchange, handler))
				.flatMap(result -> handleResult(exchange, result));
	}