@Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
   builder.routes()
        .route(r -> r.cookie("mycookie", "mycookievalue")
            .filters(f -> f.addRequestHeader("X-Request-Foo", "Bar"))
            .uri("https://example.org")
        )
        .build();
}

/**
 * 網(wǎng)關(guān)配置信息加載
 * 從appliccation.yml中解析前綴為spring.cloud.gateway的配置
 */
@ConfigurationProperties("spring.cloud.gateway")
@Validated
public class GatewayProperties {
    private final Log logger = LogFactory.getLog(this.getClass());

    /**
     * 路由定義列表
     * 加載配置key=spring.cloud.gateway.routes 列表
     * List of Routes
     */
    @NotNull
    @Valid
    private List<RouteDefinition> routes = new ArrayList();

    /**
     * 默認(rèn)的過(guò)濾器定義列表
     * 加載配置 key = spring.cloud.gateway.default-filters 列表
     * List of filter definitions that are applied to every route.
     */
    private List<FilterDefinition> defaultFilters = new ArrayList();

    /**
     * 網(wǎng)媒體類型列表
     * 加載配置 key = spring.cloud.gateway.streamingMediaTypes 列表
     * 默認(rèn)包含{text/event-stream,application/stream+json}
     */
    private List<MediaType> streamingMediaTypes;

    public GatewayProperties() {
        this.streamingMediaTypes = Arrays.asList(MediaType.TEXT_EVENT_STREAM, MediaType.APPLICATION_STREAM_JSON);
    }

    ...
}

/**
 * 路由定義實(shí)體信息，包含路由的定義信息
 */
@Validated
public class RouteDefinition {
    /**
     * 路由ID 編號(hào)，唯一
     */
    @NotEmpty
    private String id = UUID.randomUUID().toString();

    /**
     * 謂語(yǔ)定義數(shù)組
     * predicates 屬性，謂語(yǔ)定義數(shù)組
     * 請(qǐng)求通過(guò)   判斷是否匹配。在 Route 里，PredicateDefinition 轉(zhuǎn)換成 Predicate
     */
    @NotEmpty
    @Valid
    private List<PredicateDefinition> predicates = new ArrayList();

    /**
     * 過(guò)濾器定義數(shù)組
     * filters 屬性，過(guò)濾器定義數(shù)組。
     * 在 Route 里，F(xiàn)ilterDefinition 轉(zhuǎn)換成 GatewayFilter
     */
    @Valid
    private List<FilterDefinition> filters = new ArrayList();

    /**
     * 路由指向的URI
     */
    @NotNull
    private URI uri;

    /**
     * 順序
     */
    private int order = 0;

    ...
}

/**
 * 謂語(yǔ)定義,在 Route 里，PredicateDefinition 將轉(zhuǎn)換成 Predicate
 */
@Validated
public class PredicateDefinition {
    /**
     * 謂語(yǔ)定義名字
     * 通過(guò) name 對(duì)應(yīng)到 org.springframework.cloud.gateway.handler.predicate.RoutePredicateFactory 的實(shí)現(xiàn)類。
     * 例如: name=Query 對(duì)應(yīng)到 QueryRoutePredicateFactory
     */
    @NotNull
    private String name;

    /**
     * 參數(shù)數(shù)組
     * 例如，name=Host / args={"_genkey_0" : "iocoder.cn"} ，匹配請(qǐng)求的 hostname 為 iocoder.cn
     */
    private Map<String, String> args = new LinkedHashMap();

    ...
}

/**
 * 過(guò)濾器定義，在 Route 里，F(xiàn)ilterDefinition將轉(zhuǎn)換成 GatewayFilter
 */
@Validated
public class FilterDefinition {
    /**
     * 過(guò)濾器定義名字
     * 通過(guò) name 對(duì)應(yīng)到 org.springframework.cloud.gateway.filter.factory.GatewayFilterFactory 的實(shí)現(xiàn)類。
     * 例如，name=AddRequestParameter 對(duì)應(yīng)到 AddRequestParameterGatewayFilterFactory
     */
    @NotNull
    private String name;

    /**
     * 參數(shù)數(shù)組
     * 例如 name=AddRequestParameter / args={"_genkey_0": "foo", "_genkey_1": "bar"} ，添加請(qǐng)求參數(shù) foo 為 bar
     */
    private Map<String, String> args = new LinkedHashMap();

    ...
}

@Bean
@Primary
public RouteDefinitionLocator routeDefinitionLocator(List<RouteDefinitionLocator> routeDefinitionLocators) {
    return new CompositeRouteDefinitionLocator(Flux.fromIterable(routeDefinitionLocators));
}

public class PropertiesRouteDefinitionLocator implements RouteDefinitionLocator {
    private final GatewayProperties properties;

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

    public Flux<RouteDefinition> getRouteDefinitions() {
        // 從 GatewayProperties 獲取路由配置數(shù)組。
        return Flux.fromIterable(this.properties.getRoutes());
    }
}

public class InMemoryRouteDefinitionRepository implements RouteDefinitionRepository {
    /**
        * 路由配置映射 通過(guò)此來(lái)保存route
     * key ：路由編號(hào) {@link RouteDefinition#id}
     */
    private final Map<String, RouteDefinition> routes = Collections.synchronizedMap(new LinkedHashMap());

    public InMemoryRouteDefinitionRepository() {
    }

    public Mono<Void> save(Mono<RouteDefinition> route) {
        return route.flatMap((r) -> {
            this.routes.put(r.getId(), r);
            return Mono.empty();
        });
    }

    public Mono<Void> delete(Mono<String> routeId) {
        return routeId.flatMap((id) -> {
            if (this.routes.containsKey(id)) {
                this.routes.remove(id);
                return Mono.empty();
            } else {
                return Mono.defer(() -> {
                    return Mono.error(new NotFoundException("RouteDefinition not found: " + routeId));
                });
            }
        });
    }

    public Flux<RouteDefinition> getRouteDefinitions() {
        return Flux.fromIterable(this.routes.values());
    }
}

public class DiscoveryClientRouteDefinitionLocator implements RouteDefinitionLocator {
    private static final Log log = LogFactory.getLog(DiscoveryClientRouteDefinitionLocator.class);
    private final DiscoveryClient discoveryClient;
    private final DiscoveryLocatorProperties properties;
    private final String routeIdPrefix;
    private final SimpleEvaluationContext evalCtxt;

    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() + "_";
        }

        this.evalCtxt = SimpleEvaluationContext.forReadOnlyDataBinding().withInstanceMethods().build();
    }

    public Flux<RouteDefinition> getRouteDefinitions() {
        SpelExpressionParser parser = new SpelExpressionParser();
        Expression includeExpr = parser.parseExpression(this.properties.getIncludeExpression());
        Expression urlExpr = parser.parseExpression(this.properties.getUrlExpression());
        Predicate includePredicate;
        if (this.properties.getIncludeExpression() != null && !"true".equalsIgnoreCase(this.properties.getIncludeExpression())) {
            includePredicate = (instance) -> {
                Boolean include = (Boolean)includeExpr.getValue(this.evalCtxt, instance, Boolean.class);
                return include == null ? false : include;
            };
        } else {
            includePredicate = (instance) -> {
                return true;
            };
        }
        // 獲取discoveryClient，然后發(fā)起請(qǐng)求
        Flux var10000 = Flux.fromIterable(this.discoveryClient.getServices());
        DiscoveryClient var10001 = this.discoveryClient;
        var10001.getClass();
        return var10000.map(var10001::getInstances).filter((instances) -> {
            return !instances.isEmpty();
        }).map((instances) -> {
            return (ServiceInstance)instances.get(0);
        }).filter(includePredicate).map((instance) -> {
            String serviceId = instance.getServiceId();
            RouteDefinition routeDefinition = new RouteDefinition();
            // 設(shè)置 ID
            routeDefinition.setId(this.routeIdPrefix + serviceId);
            // 設(shè)置 uri
            String uri = (String)urlExpr.getValue(this.evalCtxt, instance, String.class);
            routeDefinition.setUri(URI.create(uri));
            ServiceInstance instanceForEval = new DiscoveryClientRouteDefinitionLocator.DelegatingServiceInstance(instance, this.properties);
            Iterator var8 = this.properties.getPredicates().iterator();

            Iterator var11;
            Entry entry;
            String value;

            while(var8.hasNext()) {
                PredicateDefinition originalx = (PredicateDefinition)var8.next();
                // 添加 path 斷言
                PredicateDefinition predicate = new PredicateDefinition();
                predicate.setName(originalx.getName());
                var11 = originalx.getArgs().entrySet().iterator();

                while(var11.hasNext()) {
                    entry = (Entry)var11.next();
                    value = this.getValueFromExpr(this.evalCtxt, parser, instanceForEval, entry);
                    predicate.addArg((String)entry.getKey(), value);
                }

                routeDefinition.getPredicates().add(predicate);
            }

            var8 = this.properties.getFilters().iterator();

            while(var8.hasNext()) {
                FilterDefinition original = (FilterDefinition)var8.next();
                // 添加path 重寫過(guò)濾器
                FilterDefinition filter = new FilterDefinition();
                filter.setName(original.getName());
                var11 = original.getArgs().entrySet().iterator();

                while(var11.hasNext()) {
                    entry = (Entry)var11.next();
                    value = this.getValueFromExpr(this.evalCtxt, parser, instanceForEval, entry);
                    filter.addArg((String)entry.getKey(), value);
                }

                routeDefinition.getFilters().add(filter);
            }

            return routeDefinition;
        });
    }

    ...
}

// 開啟Eureka
@EnableDiscoveryClient 
public class GatewaySampleApplication {
    // ... 省略其他代碼

    @Bean
    public RouteDefinitionLocator discoveryClientRouteDefinitionLocator(DiscoveryClient discoveryClient) {
        return new DiscoveryClientRouteDefinitionLocator(discoveryClient);
    }
}

public class CachingRouteDefinitionLocator implements RouteDefinitionLocator, ApplicationListener<RefreshRoutesEvent> {
    private final RouteDefinitionLocator delegate;
    private final Flux<RouteDefinition> routeDefinitions;
    // 收集Route
    private final Map<String, List> cache = new HashMap();

    public CachingRouteDefinitionLocator(RouteDefinitionLocator delegate) {
        this.delegate = delegate;
        FluxCacheBuilderMapMiss var10001 = CacheFlux.lookup(this.cache, "routeDefs", RouteDefinition.class);
        RouteDefinitionLocator var10002 = this.delegate;
        var10002.getClass();
        this.routeDefinitions = var10001.onCacheMissResume(var10002::getRouteDefinitions);
    }

    public Flux<RouteDefinition> getRouteDefinitions() {
        return this.routeDefinitions;
    }

    public Flux<RouteDefinition> refresh() {
        this.cache.clear();
        return this.routeDefinitions;
    }

    public void onApplicationEvent(RefreshRoutesEvent event) {
        this.refresh();
    }

    /** @deprecated */
    @Deprecated
    void handleRefresh() {
        this.refresh();
    }
}

public class CompositeRouteDefinitionLocator implements RouteDefinitionLocator {
    // RouteDefinitionLocator 數(shù)組
    private final Flux<RouteDefinitionLocator> delegates;

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

    // 將組合的 delegates 的路由定義全部返回。
    public Flux<RouteDefinition> getRouteDefinitions() {
        return this.delegates.flatMap(RouteDefinitionLocator::getRouteDefinitions);
    }
}

2、編程方式

// org.springframework.cloud.gateway.sample.GatewaySampleApplication
@SpringBootConfiguration
@EnableAutoConfiguration
@Import(AdditionalRoutesImportSelector.class)
public class GatewaySampleApplication {

    public static final String HELLO_FROM_FAKE_ACTUATOR_METRICS_GATEWAY_REQUESTS = "hello from fake /actuator/metrics/gateway.requests";

    @Value("${test.uri:http://httpbin.org:80}")
    String uri;

    public static void main(String[] args) {
        SpringApplication.run(GatewaySampleApplication.class, args);
    }

    @Bean
    public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
        // @formatter:off
        // String uri = "http://httpbin.org:80";
        // String uri = "http://localhost:9080";
        // ① RouteLocatorBuilder 可以構(gòu)建多個(gè)路由信息。
        return builder.routes()
                // ② 指定了 Predicates，這里包含兩個(gè)：
                // 請(qǐng)求頭Host需要匹配**.abc.org，通過(guò) HostRoutePredicateFactory 產(chǎn)生。
                // 請(qǐng)求路徑需要匹配/anything/png，通過(guò) PathRoutePredicateFactory 產(chǎn)生。
                .route(r -> r.host("**.abc.org").and().path("/anything/png")
                    // ③ 指定了一個(gè) Filter，下游服務(wù)響應(yīng)后添加響應(yīng)頭X-TestHeader:foobar，
                    // 通過(guò) AddResponseHeaderGatewayFilterFactory 產(chǎn)生。
                    .filters(f ->
                            f.prefixPath("/httpbin")
                                    .addResponseHeader("X-TestHeader", "foobar"))
                     // ④ 指定路由轉(zhuǎn)發(fā)的目的地 uri。
                    .uri(uri)
                )
                .route("read_body_pred", r -> r.host("*.readbody.org")
                        .and().readBody(String.class,
                                        s -> s.trim().equalsIgnoreCase("hi"))
                    .filters(f -> f.prefixPath("/httpbin")
                            .addResponseHeader("X-TestHeader", "read_body_pred")
                    ).uri(uri)
                )
                .route("rewrite_request_obj", r -> r.host("*.rewriterequestobj.org")
                    .filters(f -> f.prefixPath("/httpbin")
                            .addResponseHeader("X-TestHeader", "rewrite_request")
                            .modifyRequestBody(String.class, Hello.class, MediaType.APPLICATION_JSON_VALUE,
                                    (exchange, s) -> {
                                        return Mono.just(new Hello(s.toUpperCase()));
                                    })
                    ).uri(uri)
                )
                .route("rewrite_request_upper", r -> r.host("*.rewriterequestupper.org")
                    .filters(f -> f.prefixPath("/httpbin")
                            .addResponseHeader("X-TestHeader", "rewrite_request_upper")
                            .modifyRequestBody(String.class, String.class,
                                    (exchange, s) -> {
                                        return Mono.just(s.toUpperCase() + s.toUpperCase());
                                    })
                    ).uri(uri)
                )
                .route("rewrite_response_upper", r -> r.host("*.rewriteresponseupper.org")
                    .filters(f -> f.prefixPath("/httpbin")
                            .addResponseHeader("X-TestHeader", "rewrite_response_upper")
                            .modifyResponseBody(String.class, String.class,
                                    (exchange, s) -> {
                                        return Mono.just(s.toUpperCase());
                                    })
                    ).uri(uri)
                )
                .route("rewrite_empty_response", r -> r.host("*.rewriteemptyresponse.org")
                    .filters(f -> f.prefixPath("/httpbin")
                            .addResponseHeader("X-TestHeader", "rewrite_empty_response")
                            .modifyResponseBody(String.class, String.class,
                                    (exchange, s) -> {
                                        if (s == null) {
                                            return Mono.just("emptybody");
                                        }
                                        return Mono.just(s.toUpperCase());
                                    })

                    ).uri(uri)
                )
                .route("rewrite_response_fail_supplier", r -> r.host("*.rewriteresponsewithfailsupplier.org")
                    .filters(f -> f.prefixPath("/httpbin")
                            .addResponseHeader("X-TestHeader", "rewrite_response_fail_supplier")
                            .modifyResponseBody(String.class, String.class,
                                    (exchange, s) -> {
                                        if (s == null) {
                                            return Mono.error(new IllegalArgumentException("this should not happen"));
                                        }
                                        return Mono.just(s.toUpperCase());
                                    })
                    ).uri(uri)
                )
                .route("rewrite_response_obj", r -> r.host("*.rewriteresponseobj.org")
                    .filters(f -> f.prefixPath("/httpbin")
                            .addResponseHeader("X-TestHeader", "rewrite_response_obj")
                            .modifyResponseBody(Map.class, String.class, MediaType.TEXT_PLAIN_VALUE,
                                    (exchange, map) -> {
                                        Object data = map.get("data");
                                        return Mono.just(data.toString());
                                    })
                            .setResponseHeader("Content-Type", MediaType.TEXT_PLAIN_VALUE)
                    ).uri(uri)
                )
                .route(r -> r.path("/image/webp")
                    .filters(f ->
                            f.prefixPath("/httpbin")
                                    .addResponseHeader("X-AnotherHeader", "baz"))
                    .uri(uri)
                )
                .route(r -> r.order(-1)
                    .host("**.throttle.org").and().path("/get")
                    .filters(f -> f.prefixPath("/httpbin")
                                    .filter(new ThrottleGatewayFilter()
                                    .setCapacity(1)
                                    .setRefillTokens(1)
                                    .setRefillPeriod(10)
                                    .setRefillUnit(TimeUnit.SECONDS)))
                    .uri(uri)
                )
                // ⑤ 創(chuàng)建RouteLocator實(shí)例
                .build();
        // @formatter:on
    }

    @Bean
    public RouterFunction<ServerResponse> testFunRouterFunction() {
        RouterFunction<ServerResponse> route = RouterFunctions.route(RequestPredicates.path("/testfun"),
                request -> ServerResponse.ok().body(BodyInserters.fromValue("hello")));
        return route;
    }

    @Bean
    public RouterFunction<ServerResponse> testWhenMetricPathIsNotMeet() {
        RouterFunction<ServerResponse> route = RouterFunctions
                .route(RequestPredicates.path("/actuator/metrics/gateway.requests"), request -> ServerResponse.ok()
                        .body(BodyInserters.fromValue(HELLO_FROM_FAKE_ACTUATOR_METRICS_GATEWAY_REQUESTS)));
        return route;
    }

    static class Hello {
        String message;

        Hello() {
        }

        Hello(String message) {
            this.message = message;
        }

        public String getMessage() {
            return message;
        }

        public void setMessage(String message) {
            this.message = message;
        }
    }

}

• ① 使用 Builder 模式構(gòu)建 Route

• ② 創(chuàng)建 Predicates

• ③ 創(chuàng)建 Filter

• ④ 需要轉(zhuǎn)發(fā)的目的地 uri

• ⑤ 創(chuàng)建 RouteLocator 實(shí)例

// org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder.Builder#build
public RouteLocator build() {
    return () -> {
        return Flux.fromIterable(this.routes).map((routeBuilder) -> {
            return routeBuilder.build(); // ①
        });
    };
}

// RouteLocator 是 Route 集合
public interface RouteLocator {
    Flux<Route> getRoutes();
}

上面 build 方法返回的是 RouteLocator 對(duì)象，它是 Route 的集合所以上面 ① 中的 build 方法就是對(duì)應(yīng)的 Route。

public Route build() {
    Assert.notNull(this.id, "id can not be null");
    Assert.notNull(this.uri, "uri can not be null");
    AsyncPredicate<ServerWebExchange> predicate = this.getPredicate();
    Assert.notNull(predicate, "predicate can not be null");
    return new Route(this.id, this.uri, this.order, predicate, this.gatewayFilters);
}

下面這個(gè)就是我們最重要的 Route 數(shù)據(jù)模型了，我們來(lái)看下是如何設(shè)計(jì)的吧。

public class Route implements Ordered {
    // id，標(biāo)識(shí)符，區(qū)別于其他 Route。
    private final String id;
    // destination uri，路由指向的目的地 uri，即客戶端請(qǐng)求最終被轉(zhuǎn)發(fā)的目的地。
    private final URI uri;
    // order，用于多個(gè) Route 之間的排序，數(shù)值越小排序越靠前，匹配優(yōu)先級(jí)越高。
    private final int order;
    // predicate，謂語(yǔ)，表示匹配該 Route 的前置條件，即滿足相應(yīng)的條件才會(huì)被路由到目的地 uri。
    private final AsyncPredicate<ServerWebExchange> predicate;
    // gateway filters，過(guò)濾器用于處理切面邏輯，如路由轉(zhuǎn)發(fā)前修改請(qǐng)求頭等。
    private final List<GatewayFilter> gatewayFilters;

    ...
}

到這里，外部化配置的 Route、Predicate、Filter 會(huì)被映射成 RouteDefinition、FilterDefinition、PredicateDefinition，而編碼方式會(huì)被映射成 Route、AsyncPredicate 、GatewayFilter。

有時(shí)候我們可能又有外部化配置又有編碼方式的配置，那么這時(shí)候就需要有一個(gè)轉(zhuǎn)換。那接下來(lái)就看一下 Gateway 是如何轉(zhuǎn)換的。

四、RouteDefinitionRouteLocator

這里將 RouteDefinitionRouteLocator 單獨(dú)作為一小節(jié)來(lái)說(shuō)，RouteDefinitionRouteLocator 將外部化配置的 RouteDefinition、FilterDefinition、PredicateDefinition 轉(zhuǎn)換成 Route、AsyncPredicate、GatewayFilter。

上一篇我們講到的核心配置類 GatewayAutoConfiguration，給我提供了分析的入口，代碼如下：

// ① GatewayProperties 
// ② RouteDefinitionLocator 
@Bean
public RouteLocator routeDefinitionRouteLocator(GatewayProperties properties, List<GatewayFilterFactory> GatewayFilters, List<RoutePredicateFactory> predicates, RouteDefinitionLocator routeDefinitionLocator, @Qualifier("webFluxConversionService") ConversionService conversionService) {
    // ③ 這里進(jìn)行轉(zhuǎn)換
    return new RouteDefinitionRouteLocator(routeDefinitionLocator, predicates, GatewayFilters, properties, conversionService);
}

1、①、② 在上面外部化配置講過(guò)，這里就不重復(fù)闡述了。

2、③ 外部化配置進(jìn)行轉(zhuǎn)換，RouteDefinitionRouteLocator 是 RouteLocator 的實(shí)現(xiàn)

public class RouteDefinitionRouteLocator implements RouteLocator, BeanFactoryAware, ApplicationEventPublisherAware {
    protected final Log logger = LogFactory.getLog(this.getClass());
    public static final String DEFAULT_FILTERS = "defaultFilters";
    // RouteDefinition Locator，一個(gè) RouteDefinitionLocator 對(duì)象。
    private final RouteDefinitionLocator routeDefinitionLocator;
    private final ConversionService conversionService;
    /**
        * predicates factories，Predicate 工廠列表，會(huì)被映射成 key 為 name, value 為 factory 的 Map。
     * 可以猜想出 gateway 是如何根據(jù) PredicateDefinition 中定義的 name 來(lái)匹配到相對(duì)應(yīng)的 factory 了。
     * key ：{@link RoutePredicateFactory#name()}
     */
    private final Map<String, RoutePredicateFactory> predicates = new LinkedHashMap();
    /**
     * filter factories，Gateway Filter 工廠列表，同樣會(huì)被映射成 key 為 name, value 為 factory 的 Map。
       * key ：{@link GatewayFilterFactory#name()}
        */
    private final Map<String, GatewayFilterFactory> gatewayFilterFactories = new HashMap();
    // gateway properties，外部化配置類。
    private final GatewayProperties gatewayProperties;
    private final SpelExpressionParser parser = new SpelExpressionParser();
    private BeanFactory beanFactory;
    private ApplicationEventPublisher publisher;
    @Autowired
    private Validator validator;

    public RouteDefinitionRouteLocator(RouteDefinitionLocator routeDefinitionLocator, List<RoutePredicateFactory> predicates, List<GatewayFilterFactory> gatewayFilterFactories, GatewayProperties gatewayProperties, ConversionService conversionService) {
        // 設(shè)置 RouteDefinitionLocator
        this.routeDefinitionLocator = routeDefinitionLocator;
        this.conversionService = conversionService;
        // ① 初始化 RoutePredicateFactory
        this.initFactories(predicates);
        // ② 初始化 gatewayFilterFactories
        gatewayFilterFactories.forEach((factory) -> {
            GatewayFilterFactory var10000 = (GatewayFilterFactory)this.gatewayFilterFactories.put(factory.name(), factory);
        });
        // 設(shè)置 GatewayProperties
        this.gatewayProperties = gatewayProperties;
    }

    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
    }

    public void setApplicationEventPublisher(ApplicationEventPublisher publisher) {
        this.publisher = publisher;
    }

    // ③ 實(shí)現(xiàn) RouteLocator 的 getRoutes() 方法 獲取 route
    public Flux<Route> getRoutes() {
        // 調(diào)用 convertToRoute 方法將 RouteDefinition 轉(zhuǎn)換成 Route。
        return this.routeDefinitionLocator.getRouteDefinitions().map(this::convertToRoute).map((route) -> {
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("RouteDefinition matched: " + route.getId());
            }

            return route;
        });
    }

    ...
}

2.1 ① 初始化 RoutePredicateFactory

private void initFactories(List<RoutePredicateFactory> 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 (this.logger.isInfoEnabled()) {
            this.logger.info("Loaded RoutePredicateFactory [" + key + "]");
        }

    });
}

2.2 ② 初始化 gatewayFilterFactories

// FilterDefinition 轉(zhuǎn)換成 GatewayFilter
private List<GatewayFilter> getFilters(RouteDefinition routeDefinition) {
    List<GatewayFilter> filters = new ArrayList();
    // ① 處理 GatewayProperties 中定義的默認(rèn)的 FilterDefinition，轉(zhuǎn)換成 GatewayFilter。
    if (!this.gatewayProperties.getDefaultFilters().isEmpty()) {
        filters.addAll(this.loadGatewayFilters("defaultFilters", this.gatewayProperties.getDefaultFilters()));
    }
    // ② 將 RouteDefinition 中定義的 FilterDefinition 轉(zhuǎn)換成 GatewayFilter。
    if (!routeDefinition.getFilters().isEmpty()) {
        filters.addAll(this.loadGatewayFilters(routeDefinition.getId(), routeDefinition.getFilters()));
    }
    // ③ 對(duì) GatewayFilter 進(jìn)行排序，排序的詳細(xì)邏輯請(qǐng)查閱 spring 中的 Ordered 接口。
    AnnotationAwareOrderComparator.sort(filters);
    return filters;
}

2.3 ③ 實(shí)現(xiàn) RouteLocator 的 getRoutes() 方法 獲取 Route，真正轉(zhuǎn)換的方法

public Flux<Route> getRoutes() {
    // 調(diào)用 convertToRoute 方法將 RouteDefinition 轉(zhuǎn)換成 Route。
    return this.routeDefinitionLocator.getRouteDefinitions().map(this::convertToRoute).map((route) -> {
        if (this.logger.isDebugEnabled()) {
            this.logger.debug("RouteDefinition matched: " + route.getId());
        }

        return route;
    });
}

private Route convertToRoute(RouteDefinition routeDefinition) {
    // 2.3.1 將 PredicateDefinition 轉(zhuǎn)換成 AsyncPredicate。
    AsyncPredicate<ServerWebExchange> predicate = this.combinePredicates(routeDefinition);
    // 2.3.2 將 FilterDefinition 轉(zhuǎn)換成 GatewayFilter。
    List<GatewayFilter> gatewayFilters = this.getFilters(routeDefinition);
    // 2.3.3 根據(jù) 1 和 2 兩步驟定義的變量生成 Route 對(duì)象。
    return ((AsyncBuilder)Route.async(routeDefinition).asyncPredicate(predicate).replaceFilters(gatewayFilters)).build();
}

2.3.1 將 PredicateDefinition 轉(zhuǎn)換成 AsyncPredicate

private AsyncPredicate<ServerWebExchange> combinePredicates(RouteDefinition routeDefinition) {
    List<PredicateDefinition> predicates = routeDefinition.getPredicates();
    // ① 調(diào)用 lookup 方法，將列表中第一個(gè) PredicateDefinition 轉(zhuǎn)換成 AsyncPredicate。
    AsyncPredicate<ServerWebExchange> predicate = this.lookup(routeDefinition, (PredicateDefinition)predicates.get(0));

    AsyncPredicate found;
    // ② 循環(huán)調(diào)用，將列表中每一個(gè) PredicateDefinition 都轉(zhuǎn)換成 AsyncPredicate。
    // ③ 應(yīng)用and操作，將所有的 AsyncPredicate 組合成一個(gè) AsyncPredicate 對(duì)象。
    for(Iterator var4 = predicates.subList(1, predicates.size()).iterator(); var4.hasNext(); predicate = predicate.and(found)) {
        PredicateDefinition andPredicate = (PredicateDefinition)var4.next();
        found = this.lookup(routeDefinition, andPredicate);
    }

    return predicate;
}

2.3.2 將 FilterDefinition 轉(zhuǎn)換成 GatewayFilter

// FilterDefinition 轉(zhuǎn)換成 GatewayFilter
private List<GatewayFilter> getFilters(RouteDefinition routeDefinition) {
    List<GatewayFilter> filters = new ArrayList();
    // ① 處理 GatewayProperties 中定義的默認(rèn)的 FilterDefinition，轉(zhuǎn)換成 GatewayFilter。
    if (!this.gatewayProperties.getDefaultFilters().isEmpty()) {
        filters.addAll(this.loadGatewayFilters("defaultFilters", this.gatewayProperties.getDefaultFilters()));
    }
    // ② 將 RouteDefinition 中定義的 FilterDefinition 轉(zhuǎn)換成 GatewayFilter。
    if (!routeDefinition.getFilters().isEmpty()) {
        filters.addAll(this.loadGatewayFilters(routeDefinition.getId(), routeDefinition.getFilters()));
    }
    // ③ 對(duì) GatewayFilter 進(jìn)行排序，排序的詳細(xì)邏輯請(qǐng)查閱 spring 中的 Ordered 接口。
    AnnotationAwareOrderComparator.sort(filters);
    return filters;
}

2.3.3 根據(jù) 2.3.1 和 2.3.2 兩步驟定義的變量生成 Route 對(duì)象

public Route build() {
    Assert.notNull(this.id, "id can not be null");
    Assert.notNull(this.uri, "uri can not be null");
    AsyncPredicate<ServerWebExchange> predicate = this.getPredicate();
    Assert.notNull(predicate, "predicate can not be null");
    return new Route(this.id, this.uri, this.order, predicate, this.gatewayFilters);
}

到這里我們就已經(jīng)知道外部化配置配合是如何轉(zhuǎn)換的，那么現(xiàn)在 Route 已經(jīng)組裝完畢了，現(xiàn)在就是看一下 Route 里面的 Predicate 和 Filter 的實(shí)現(xiàn)。