AddHttpClient失败，返回DefaultHttpClientFactory [英] AddHttpClient fails with DefaultHttpClientFactory
本文介绍了AddHttpClient失败，返回DefaultHttpClientFactory的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
在我的API启动时，我在ConfigureServices中声明了一个外部API的客户端：
services.AddTransient<ApiBearerTokenHandler>();
services.AddHttpClient<IExternalApi, ExternalApi>(client =>
{
client.BaseAddress = new Uri(settings.ApiUrl);
client.DefaultRequestHeaders.Add("Accept", "application/json");
}).AddHttpMessageHandler<ApiBearerTokenHandler>();
在注射时，我得到以下错误：
System.InvalidOperationException: ValueFactory attempted to access the Value property of this instance
似乎DefaultHttpClientFactory无法创建HttpClient。
我是要提供创建此客户端的方法，还是应该自动创建它？
如果我在没有此处理程序的情况下声明客户端，插入不会失败，但我没有令牌：
services.AddHttpClient<IExternalApi, ExternalApi>(client =>
{
client.BaseAddress = new Uri(settings.ApiUrl);
client.DefaultRequestHeaders.Add("Accept", "application/json");
});
漂亮堆栈：
System.InvalidOperationException: ValueFactory attempted to access the Value property of this instance.
at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
at System.Lazy`1.CreateValue()
at System.Lazy`1.get_Value()
at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateHandler(String name)
at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateClient(String name)
at Microsoft.Extensions.DependencyInjection.HttpClientBuilderExtensions.<>c__DisplayClass12_0`2.<AddTypedClientCore>b__0(IServiceProvider s)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, RuntimeResolverContext context)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
at Microsoft.Extensions.DependencyInjection.HttpClientBuilderExtensions.<>c__4`1.<AddHttpMessageHandler>b__4_1(HttpMessageHandlerBuilder b)
at Microsoft.Extensions.Http.DefaultHttpClientFactory.<>c__DisplayClass17_0.<CreateHandlerEntry>g__Configure|0(HttpMessageHandlerBuilder b)
at Microsoft.Extensions.Http.LoggingHttpMessageHandlerBuilderFilter.<>c__DisplayClass2_0.<Configure>b__0(HttpMessageHandlerBuilder builder)
at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateHandlerEntry(String name)
at Microsoft.Extensions.Http.DefaultHttpClientFactory.<>c__DisplayClass14_0.<.ctor>b__1()
at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
at System.Lazy`1.CreateValue()
at System.Lazy`1.get_Value()
at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateHandler(String name)
at Microsoft.Extensions.Http.DefaultHttpClientFactory.CreateClient(String name)
at Microsoft.Extensions.DependencyInjection.HttpClientBuilderExtensions.<>c__DisplayClass12_0`2.<AddTypedClientCore>b__0(IServiceProvider s)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, RuntimeResolverContext context)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite singletonCallSite, RuntimeResolverContext context)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired)
at lambda_method(Closure , IServiceProvider , Object[] )
at Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider.<>c__DisplayClass4_0.<CreateActivator>b__0(ControllerContext controllerContext)
at Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider.<>c__DisplayClass5_0.<CreateControllerFactory>g__CreateController|0(ControllerContext controllerContext)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
推荐答案
在我的示例中，单个接口提供身份验证和其他服务。
但我不能对两者使用相同的HttpClient，因为服务需要身份验证才能实例化。 因此，我必须将HttpClient拆分为两部分：
// 1 - authentication
services.AddHttpClient<IAuthApi, AuthApi>(client =>
{
client.BaseAddress = new Uri(settings.ApiUrl);
client.DefaultRequestHeaders.Add("Accept", "application/json");
});
// 2 - other services
services.AddTransient<ApiBearerTokenHandler>();
services.AddHttpClient<IExternalApi, ExternalApi>(client =>
{
client.BaseAddress = new Uri(settings.ApiUrl);
client.DefaultRequestHeaders.Add("Accept", "application/json");
}).AddHttpMessageHandler<ApiBearerTokenHandler>();
其中ApiBearerTokenHandler使用IAuthApi获取令牌。
这篇关于AddHttpClient失败，返回DefaultHttpClientFactory的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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