通过源码解析，发现实现一个限流还是很简单的吗！再进一步解析，IRateLimitCounterHandler ClientRateLimitProcessor里的相关接口又是怎么实现的呢？这时候我们就需要了解下.NETCORE 的运行原理，其中ConfigureServices方法实现了依赖注入(DI)的配置。这时候我们看下Ocelot是在哪里进行注入的呢？
services.AddOcelot()是不是印象深刻呢？原来所有的注入信息都写在这里，那么问题简单了，Ctrl+F查找AddOcelot方法，马上就能定位到ServiceCollectionExtensions方法，然后再转到定义OcelotBuilder
public static class ServiceCollectionExtensions { public static IOcelotBuilder AddOcelot(this IServiceCollection services) { var service = services.First(x => x.ServiceType == typeof(IConfiguration)); var configuration = (IConfiguration)service.ImplementationInstance; return new OcelotBuilder(services, configuration); } public static IOcelotBuilder AddOcelot(this IServiceCollection services, IConfiguration configuration) { return new OcelotBuilder(services, configuration); } }又摸到大动脉啦，现在问题迎刃而解，原来所有的注入都写在这里，从这里可以找下我们熟悉的几个接口注入。
public OcelotBuilder(IServiceCollection services, IConfiguration configurationRoot) { Configuration = configurationRoot; Services = services; Services.Configure<FileConfiguration>(configurationRoot); Services.TryAddSingleton<IOcelotCache<FileConfiguration>, InMemoryCache<FileConfiguration>>(); Services.TryAddSingleton<IOcelotCache<CachedResponse>, InMemoryCache<CachedResponse>>(); Services.TryAddSingleton<IHttpResponseHeaderReplacer, HttpResponseHeaderReplacer>(); Services.TryAddSingleton<IHttpContextRequestHeaderReplacer, HttpContextRequestHeaderReplacer>(); Services.TryAddSingleton<IHeaderFindAndReplaceCreator, HeaderFindAndReplaceCreator>(); Services.TryAddSingleton<IInternalConfigurationCreator, FileInternalConfigurationCreator>(); Services.TryAddSingleton<IInternalConfigurationRepository, InMemoryInternalConfigurationRepository>(); Services.TryAddSingleton<IConfigurationValidator, FileConfigurationFluentValidator>(); Services.TryAddSingleton<HostAndPortValidator>(); Services.TryAddSingleton<IReRoutesCreator, ReRoutesCreator>(); Services.TryAddSingleton<IAggregatesCreator, AggregatesCreator>(); Services.TryAddSingleton<IReRouteKeyCreator, ReRouteKeyCreator>(); Services.TryAddSingleton<IConfigurationCreator, ConfigurationCreator>(); Services.TryAddSingleton<IDynamicsCreator, DynamicsCreator>(); Services.TryAddSingleton<ILoadBalancerOptionsCreator, LoadBalancerOptionsCreator>(); Services.TryAddSingleton<ReRouteFluentValidator>(); Services.TryAddSingleton<FileGlobalConfigurationFluentValidator>(); Services.TryAddSingleton<FileQoSOptionsFluentValidator>(); Services.TryAddSingleton<IClaimsToThingCreator, ClaimsToThingCreator>(); Services.TryAddSingleton<IAuthenticationOptionsCreator, AuthenticationOptionsCreator>(); Services.TryAddSingleton<IUpstreamTemplatePatternCreator, UpstreamTemplatePatternCreator>(); Services.TryAddSingleton<IRequestIdKeyCreator, RequestIdKeyCreator>(); Services.TryAddSingleton<IServiceProviderConfigurationCreator,ServiceProviderConfigurationCreator>(); Services.TryAddSingleton<IQoSOptionsCreator, QoSOptionsCreator>(); Services.TryAddSingleton<IReRouteOptionsCreator, ReRouteOptionsCreator>(); Services.TryAddSingleton<IRateLimitOptionsCreator, RateLimitOptionsCreator>(); Services.TryAddSingleton<IBaseUrlFinder, BaseUrlFinder>(); Services.TryAddSingleton<IRegionCreator, RegionCreator>(); Services.TryAddSingleton<IFileConfigurationRepository, DiskFileConfigurationRepository>(); Services.TryAddSingleton<IFileConfigurationSetter, FileAndInternalConfigurationSetter>(); Services.TryAddSingleton<IServiceDiscoveryProviderFactory, ServiceDiscoveryProviderFactory>(); Services.TryAddSingleton<ILoadBalancerFactory, LoadBalancerFactory>(); Services.TryAddSingleton<ILoadBalancerHouse, LoadBalancerHouse>(); Services.TryAddSingleton<IOcelotLoggerFactory, AspDotNetLoggerFactory>(); Services.TryAddSingleton<IRemoveOutputHeaders, RemoveOutputHeaders>(); Services.TryAddSingleton<IClaimToThingConfigurationParser, ClaimToThingConfigurationParser>(); Services.TryAddSingleton<IClaimsAuthoriser, ClaimsAuthoriser>(); Services.TryAddSingleton<IScopesAuthoriser, ScopesAuthoriser>(); Services.TryAddSingleton<IAddClaimsToRequest, AddClaimsToRequest>(); Services.TryAddSingleton<IAddHeadersToRequest, AddHeadersToRequest>(); Services.TryAddSingleton<IAddQueriesToRequest, AddQueriesToRequest>(); Services.TryAddSingleton<IClaimsParser, ClaimsParser>(); Services.TryAddSingleton<IUrlPathToUrlTemplateMatcher, RegExUrlMatcher>(); Services.TryAddSingleton<IPlaceholderNameAndValueFinder, UrlPathPlaceholderNameAndValueFinder>(); Services.TryAddSingleton<IDownstreamPathPlaceholderReplacer, DownstreamTemplatePathPlaceholderReplacer>(); Services.TryAddSingleton<IDownstreamRouteProvider, DownstreamRouteFinder>(); Services.TryAddSingleton<IDownstreamRouteProvider, DownstreamRouteCreator>(); Services.TryAddSingleton<IDownstreamRouteProviderFactory, DownstreamRouteProviderFactory>(); Services.TryAddSingleton<IHttpRequester, HttpClientHttpRequester>(); Services.TryAddSingleton<IHttpResponder, HttpContextResponder>(); Services.TryAddSingleton<IErrorsToHttpStatusCodeMapper, ErrorsToHttpStatusCodeMapper>(); Services.TryAddSingleton<IRateLimitCounterHandler, MemoryCacheRateLimitCounterHandler>(); Services.TryAddSingleton<IHttpClientCache, MemoryHttpClientCache>(); Services.TryAddSingleton<IRequestMapper, RequestMapper>(); Services.TryAddSingleton<IHttpHandlerOptionsCreator, HttpHandlerOptionsCreator>(); Services.TryAddSingleton<IDownstreamAddressesCreator, DownstreamAddressesCreator>(); Services.TryAddSingleton<IDelegatingHandlerHandlerFactory, DelegatingHandlerHandlerFactory>(); Services.TryAddSingleton<IHttpRequester, HttpClientHttpRequester>(); // see this for why we register this as singleton // could maybe use a scoped data repository Services.TryAddSingleton<IHttpContextAccessor, HttpContextAccessor>(); Services.TryAddSingleton<IRequestScopedDataRepository, HttpDataRepository>(); Services.AddMemoryCache(); Services.TryAddSingleton<OcelotDiagnosticListener>(); Services.TryAddSingleton<IMultiplexer, Multiplexer>(); Services.TryAddSingleton<IResponseAggregator, SimpleJsonResponseAggregator>(); Services.TryAddSingleton<ITracingHandlerFactory, TracingHandlerFactory>(); Services.TryAddSingleton<IFileConfigurationPollerOptions, InMemoryFileConfigurationPollerOptions>(); Services.TryAddSingleton<IAddHeadersToResponse, AddHeadersToResponse>(); Services.TryAddSingleton<IPlaceholders, Placeholders>(); Services.TryAddSingleton<IResponseAggregatorFactory, InMemoryResponseAggregatorFactory>(); Services.TryAddSingleton<IDefinedAggregatorProvider, ServiceLocatorDefinedAggregatorProvider>(); Services.TryAddSingleton<IDownstreamRequestCreator, DownstreamRequestCreator>(); Services.TryAddSingleton<IFrameworkDescription, FrameworkDescription>(); Services.TryAddSingleton<IQoSFactory, QoSFactory>(); Services.TryAddSingleton<IExceptionToErrorMapper, HttpExeptionToErrorMapper>(); //add security this.AddSecurity(); //add asp.net services.. var assembly = typeof(FileConfigurationController).GetTypeInfo().Assembly; Services.AddMvcCore() .AddApplicationPart(assembly) .AddControllersAsServices() .AddAuthorization() .AddJsonFormatters(); Services.AddLogging(); Services.AddMiddlewareAnalysis(); Services.AddWebEncoders(); }