NullReferenceException:对象引用未设置为对象的实例- NES.EventHandlerFactory

Question

我编写的代码如下：

public class ConferenceService
    {
        private static readonly IEventFactory _eventFactory = DI.Current.Resolve<IEventFactory>();
        private static readonly IEventHandlerFactory _eventHandlerFactory = DI.Current.Resolve<IEventHandlerFactory>();
        private readonly string nameOrConnectionString;
        private readonly RetryPolicy<SqlAzureTransientErrorDetectionStrategy> retryPolicy;

        public ConferenceService(string nameOrConnectionString = "ConferenceManagement")
        {

            this.nameOrConnectionString = nameOrConnectionString;

            this.retryPolicy = new RetryPolicy<SqlAzureTransientErrorDetectionStrategy>(new Incremental(5, TimeSpan.FromSeconds(0), TimeSpan.FromSeconds(1.5)) { FastFirstRetry = true });
            this.retryPolicy.Retrying += (s, e) =>
                Trace.TraceWarning("An error occurred in attempt number {1} to access the database in ConferenceService: {0}", e.LastException.Message, e.CurrentRetryCount);

        }

        public void CreateConference(ConferenceInfo conference)
        {
            using (var context = new ConferenceContext(this.nameOrConnectionString))
            {
                var existingSlug = this.retryPolicy.ExecuteAction(() => 
                    context.Conferences
                        .Where(c => c.Slug == conference.Slug)
                        .Select(c => c.Slug)
                        .Any());

                if (existingSlug)
                    throw new DuplicateNameException("The chosen conference slug is already taken.");

                // Conference publishing is explicit. 
                if (conference.IsPublished)
                    conference.IsPublished = false;

                context.Conferences.Add(conference);
                this.retryPolicy.ExecuteAction(() => context.SaveChanges());

               this.PublishConferenceEvent<ConferenceCreated>(conference);
            }
        }


        private void PublishConferenceEvent<T>(ConferenceInfo conference)
            where T : ConferenceEvent, new()
        {

            Action<T> action = x => new T
            {
                SourceId = conference.Id,
                Owner = new Owner
                {
                    Name = conference.OwnerName,
                    Email = conference.OwnerEmail,
                },
                Name = conference.Name,
                Description = conference.Description,
                Location = conference.Location,
                Slug = conference.Slug,
                Tagline = conference.Tagline,
                TwitterSearch = conference.TwitterSearch,
                StartDate = conference.StartDate,
                EndDate = conference.EndDate,
            };

            Apply(action);
        }


        private void Apply<TEvent>(Action<TEvent> action)
        {
           var @event = _eventFactory.Create(action);
           Raise(@event);
        }

        private void Raise(object @event)
        {
            _eventHandlerFactory.Get(this, @event.GetType())(@event);
        }
    }

但是，当我运行我的代码并尝试创建一个会议时，它会显示以下异常消息：

对象引用未设置为对象的实例. 描述:在执行当前web请求时发生了未处理的异常。请查看堆栈跟踪以获得有关错误的更多信息，以及它起源于代码的位置。 异常详细信息: System.NullReferenceException:对象引用未设置为对象的实例。 源错误： 第10行:公共类EventHandlerFactory : IEventHandlerFactory第11行：{第12行:私有静态只读ILogger Logger =IEventHandlerFactory第13行:私有静态只读Dictionary>> _cache =新Dictionary>>()；第14行:私有静态只读对象_cacheLock =新对象()； 源文件: F:\MyProjects\NES\NES-master\src\NES\EventHandlerFactory.cs行: 12 堆栈跟踪： NullReferenceException:对象引用没有设置为对象的实例。F:\MyProjects\NES\NES-master\src\NES\EventHandlerFactory.cs:12中的NES.EventHandlerFactory..cctor() TypeInitializationException：“NES.EventHandlerFactory”的类型初始化程序引发了一个异常。 NES.EventHandlerFactory..ctor() +0 NES.<>c.<.cctor>b__4_4()，F:\MyProjects\NES\NES-master\src\NES\DI.cs:24 F:\MyProjects\NES\NES-master\src\NES\DependencyInjectionContainer.cs:21 Conference.ConferenceService..cctor()中的NES.DependencyInjectionContainer.Resolve()在F:\MyProjects\NES\NES-master\samples\Conference\ConferenceService.cs:23中 TypeInitializationException：“Conference.ConferenceService”的类型初始化程序引发了一个异常。 F:\MyProjects\NES\NES-master\samples\Conference\ConferenceService.cs:36 Conference.Web.Admin.Controllers.ConferenceController.get_Service() in F:\MyProjects\NES\NES-master\samples\Conference.Web.Admin\Controllers\ConferenceController.cs:32 Conference.Web.Admin.Controllers.ConferenceController.Create(ConferenceInfo F:\MyProjects\NES\NES-master\samples\Conference.Web.Admin\Controllers\ConferenceController.cs:119 lambda_method中的Conference.ConferenceService..ctor(String nameOrConnectionString)( Object[] ) +180 System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase控制器，Object[]参数) +68 System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext，IDictionary2 parameters) +486 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2参数) +71 System.Web.Mvc.Async.ActionInvocation.InvokeSynchronousActionMethod() +85 System.Web.Mvc.Async.AsyncControllerActionInvoker.b__39(IAsyncResult asyncResult，ActionInvocation innerInvokeState) +44 System.Web.Mvc.Async.WrappedAsyncResult2.CallEndDelegate(IAsyncResult asyncResult) +82 System.Web.Mvc.Async.WrappedAsyncResultBase1.结尾() +143 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult，对象标签) +109 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +58 System.Web.Mvc.Async.AsyncInvocationWithFilters.b__3d() +121 System.Web.Mvc.Async.<>c__DisplayClass46.b__3f() +321 System.Web.Mvc.Async.<>c__DisplayClass33.b__32(IAsyncResult asyncResult) +53 System.Web.Mvc.Async.WrappedAsyncResult1.CallEndDelegate(IAsyncResult asyncResult) +56 System.Web.Mvc.Async.WrappedAsyncResultBase1.结尾() +143 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult，对象标签) +109 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +58 System.Web.Mvc.Async.<>c__DisplayClass2b.b__1c() +76 System.Web.Mvc.Async.<>c__DisplayClass21.b__1e(IAsyncResult asyncResult) +184号 System.Web.Mvc.Async.WrappedAsyncResult1.CallEndDelegate(IAsyncResult asyncResult) +53 System.Web.Mvc.Async.WrappedAsyncResultBase1.140() +140 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult，对象标签) +63 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +50 System.Web.Mvc.Controller.b__1d(IAsyncResult asyncResult，ExecuteCoreState innerState) +45 System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) +81 System.Web.Mvc.Async.WrappedAsyncResultBase1.140() +140 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult，对象标签) +63 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult，对象标签) +47 ( System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +50 System.Web.Mvc.Controller.b__15(IAsyncResult asyncResult，控制器) +50 System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) +73 System.Web.Mvc.Async.WrappedAsyncResultBase1.140() +140 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult，对象标签) +63 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult，对象标签) +47 System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +50 System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +50 System.Web.Mvc.MvcHandler.b__5(IAsyncResult asyncResult，ProcessRequestState innerState) +45 System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) +81 System.Web.Mvc.Async.WrappedAsyncResultBase1.140() +140 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult，对象标签) +63 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult，对象标签) +47 ( System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +50 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult结果) +49 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9644037 System.Web.HttpApplication.ExecuteStep(IExecutionStep step，布尔& completedSynchronously) +155

Answer 1

问题已经解决了。这个问题是由于配置引起的。最后，我通过在Application_Start() Global.asax方法中添加以下代码来解决这个问题。

LogManager.Use<NServiceBus.Log4Net.Log4NetFactory>();