SpringCloud Gateway加载断言predicates与过滤器filters的源码分析

<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>

spring:
  cloud:
    gateway:
      routes:
       - id: after-route #id必须要唯一
         uri: lb://product-center
         predicates:
          - After=2030-12-16T15:53:22.999+08:00[Asia/Shanghai]
        filters:
          - PrefixPath=/product-api

@Bean
    public RouteLocator routeDefinitionRouteLocator(GatewayProperties properties,
                                                   List<GatewayFilterFactory> GatewayFilters,
                                                   List<RoutePredicateFactory> predicates,
                                                   RouteDefinitionLocator routeDefinitionLocator) {
        return new RouteDefinitionRouteLocator(routeDefinitionLocator, predicates, GatewayFilters, properties);
    }

    @Bean
    @Primary
    //TODO: property to disable composite?
    public RouteLocator cachedCompositeRouteLocator(List<RouteLocator> routeLocators) {
        return new CachingRouteLocator(new CompositeRouteLocator(Flux.fromIterable(routeLocators)));
    }

public BeanWrapper instantiateUsingFactoryMethod(
            String beanName, RootBeanDefinition mbd, @Nullable Object[] explicitArgs) {

        .....

            for (Method candidate : candidates) {
                Class<?>[] paramTypes = candidate.getParameterTypes();

                if (paramTypes.length >= minNrOfArgs) {
                    ArgumentsHolder argsHolder;

                    if (explicitArgs != null) {
                        // Explicit arguments given -> arguments length must match exactly.
                        if (paramTypes.length != explicitArgs.length) {
                            continue;
                        }
                        argsHolder = new ArgumentsHolder(explicitArgs);
                    }
                    else {
                        // Resolved constructor arguments: type conversion and/or autowiring necessary.
                        try {
                            String[] paramNames = null;
                            ParameterNameDiscoverer pnd = this.beanFactory.getParameterNameDiscoverer();
                            if (pnd != null) {
                                paramNames = pnd.getParameterNames(candidate);
                            }
                            //主要就是会进入到这里去解析每一个参数类型
                            argsHolder = createArgumentArray(beanName, mbd, resolvedValues, bw,
                                    paramTypes, paramNames, candidate, autowiring, candidates.length == 1);
                        }
                        catch (UnsatisfiedDependencyException ex) {
                            if (logger.isTraceEnabled()) {
                                logger.trace("Ignoring factory method [" + candidate + "] of bean '" + beanName + "': " + ex);
                            }
                            // Swallow and try next overloaded factory method.
                            if (causes == null) {
                                causes = new LinkedList<>();
                            }
                            causes.add(ex);
                            continue;
                        }
                    }

                    int typeDiffWeight = (mbd.isLenientConstructorResolution() ?
                            argsHolder.getTypeDifferenceWeight(paramTypes) : argsHolder.getAssignabilityWeight(paramTypes));
                    // Choose this factory method if it represents the closest match.
                    if (typeDiffWeight < minTypeDiffWeight) {
                        factoryMethodToUse = candidate;
                        argsHolderToUse = argsHolder;
                        argsToUse = argsHolder.arguments;
                        minTypeDiffWeight = typeDiffWeight;
                        ambiguousFactoryMethods = null;
                    }
                    // Find out about ambiguity: In case of the same type difference weight
                    // for methods with the same number of parameters, collect such candidates
                    // and eventually raise an ambiguity exception.
                    // However, only perfORM that check in non-lenient constructor resolution mode,
                    // and explicitly ignore overridden methods (with the same parameter signature).
                    else if (factoryMethodToUse != null && typeDiffWeight == minTypeDiffWeight &&
                            !mbd.isLenientConstructorResolution() &&
                            paramTypes.length == factoryMethodToUse.getParameterCount() &&
                            !Arrays.equals(paramTypes, factoryMethodToUse.getParameterTypes())) {
                        if (ambiguousFactoryMethods == null) {
                            ambiguousFactoryMethods = new LinkedHashSet<>();
                            ambiguousFactoryMethods.add(factoryMethodToUse);
                        }
                        ambiguousFactoryMethods.add(candidate);
                    }
                }
            }

            .....
        return bw;
    }

private ArgumentsHolder createArgumentArray(
            String beanName, RootBeanDefinition mbd, @Nullable ConstructorArgumentValues resolvedValues,
            BeanWrapper bw, Class<?>[] paramTypes, @Nullable String[] paramNames, Executable executable,
            boolean autowiring, boolean fallback) throws UnsatisfiedDependencyException {

        ....
        //这下就是了，每个参数都被进行解析
        for (int paramIndex = 0; paramIndex < paramTypes.length; paramIndex++) {
            ....
                try {
                //我们的参数就是在这里被进行解析的--resolveAutowiredArgument
                    Object autowiredArgument = resolveAutowiredArgument(
                            methodParam, beanName, autowiredBeanNames, converter, fallback);
                    args.rawArguments[paramIndex] = autowiredArgument;
                    args.arguments[paramIndex] = autowiredArgument;
                    args.preparedArguments[paramIndex] = new AutowiredArgumentMarker();
                    args.resolveNecessary = true;
                }
                catch (BeansException ex) {
                    throw new UnsatisfiedDependencyException(
                            mbd.getResourceDescription(), beanName, new InjectionPoint(methodParam), ex);
                }
            }
        }
        //其他不重要的，直接忽略掉
        ...
        return args;
    }

protected Map<String, Object> findAutowireCandidates(
            @Nullable String beanName, Class<?> requiredType, DependencyDescriptor descriptor) {
        //主要的就是这个，beanNamesForTypeIncludingAncestors方法，该方法就是从bean工厂中获取所有当前类的实现实例名称，
        String[] candidateNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
                this, requiredType, true, descriptor.isEager());
        Map<String, Object> result = new LinkedHashMap<>(candidateNames.length);
        ...
        //遍历名称，进行实例化
        for (String candidate : candidateNames) {
            if (!isSelfReference(beanName, candidate) && isAutowireCandidate(candidate, descriptor)) {
                addCandidateEntry(result, candidate, descriptor, requiredType);
            }
        }
        .....
        return result;
    }

public RouteDefinitionRouteLocator(RouteDefinitionLocator routeDefinitionLocator,
                                       List<RoutePredicateFactory> predicates,
                                       List<GatewayFilterFactory> gatewayFilterFactories,
                                       GatewayProperties gatewayProperties) {
        this.routeDefinitionLocator = routeDefinitionLocator;
        initFactories(predicates);
        gatewayFilterFactories.forEach(factory -> this.gatewayFilterFactories.put(factory.name(), factory));
        this.gatewayProperties = gatewayProperties;
    }

 default String name() {
        return NameUtils.normalizeRoutePredicateName(getClass());
    }