Csharp 在. NET Core 8 Web API中，当为服务总线使用通用消费者时，如何防止IServiceProvider被释放或空"

当在. NET Core 8 Web API应用程序中为服务总线实现通用消费者时，我遇到了一个问题，即当试图解决消费者中的依赖关系时，IServiceProvider实例被释放或为null.如何确保IServiceProvider在使用者中保持有效和可访问，以正确解决依赖关系(如事件处理器策略)而不被丢弃？

背景: 我试图实现的是一种可重用的通用方法，用于在多个微服务之间订阅服务总线主题.每个微服务都应该能够轻松地实现这个通用类，并提供自己的策略来处理接收到的事件.

我正在使用HostedService，特别是PostConsumerHostedService，它负责触发消费者逻辑.

当try 在使用者中使用IServiceProvider时会出现问题，因为发现它在运行时被释放.

首先，这里是触发消费者的PostConsumerHostedService:

    public class PostConsumerHostedService : CronJobServiceBase
{
    private readonly IServiceProvider _service;

    public PostConsumerHostedService(
        IOptions<PostConsumerHostedServiceSettings> postConsumerHostedServiceSettings,
        ILogger<CronJobServiceBase> log,
        IServiceProvider service)
        : base(postConsumerHostedServiceSettings, log)
    {
        _service = service;
    }

    protected override async Task ExecuteTaskAsync(CancellationToken cancellationToken)
    {
        using var scope = _service.CreateAsyncScope();
        var postTaskService = scope.ServiceProvider.GetRequiredService<IPostConsumerTaskService>();
        await postTaskService.StartAsync(cancellationToken);
    }
}

接下来，调用IServiceBusConsumer的PostConsumerTaskService:

public interface IPostConsumerTaskService : ITaskService, IHandleServiceBusMessage
    {
    }
public class PostConsumerTaskService : IPostConsumerTaskService
{
    private readonly IServiceBusConsumer _serviceBusConsumer;
    private readonly IServiceProvider _serviceProvider;

    public PostConsumerTaskService(
        IServiceBusConsumer serviceBusConsumer,
        IServiceProvider serviceProvider)
    {
        _serviceBusConsumer = serviceBusConsumer;
        _serviceProvider = serviceProvider;
    }

    public async Task HandleStringMessageAsync(string message)
    {
        var jsonDocument = JsonDocument.Parse(message);

        // Extract the value of the "type" field
        if (jsonDocument.RootElement.TryGetProperty("EventType", out JsonElement typeElement))
        {
            string type = typeElement.GetString();
            Console.WriteLine("Type: " + type);
            Enum.TryParse(type, out EventType myEvent);

            var eventStrategy = await _eventProcessorFactory.GetEventProcessorStrategy(_serviceProvider,myEvent);
            eventStrategy.ProcessEvent(message);
        }
        else
        {
            Console.WriteLine("Type field not found in JSON.");
        }

        await Task.CompletedTask;
    }

    public async Task StartAsync(CancellationToken cancellationToken)
    {
        await _serviceBusConsumer.StartAsync<LikeCreated>(this, cancellationToken);
    }
}

下面是ServiceBusConsumerBase，当试图检索事件处理器策略时，问题发生在这里:

public abstract class ServiceBusConsumerBase: IServiceBusConsumer
{
    private readonly ServiceBusConsumerSettingsBase _serviceBusConsummerSettings;

    public ServiceBusConsumerBase(IOptions<ServiceBusConsumerSettingsBase> serviceBusConsummerSettings)
    {
        _serviceBusConsummerSettings = serviceBusConsummerSettings.Value;
    }

    public async Task StartAsync<T>(IHandleServiceBusMessage handleServiceBusMessage,CancellationToken cancellationToken)
    {
        var serviceBusClient = new ServiceBusClient(_serviceBusConsummerSettings.ConnectionString);
        var processor = serviceBusClient.CreateProcessor(_serviceBusConsummerSettings.Topic, _serviceBusConsummerSettings.Subscription, new ServiceBusProcessorOptions
        {
            AutoCompleteMessages = false,
            MaxConcurrentCalls = 1
        });


        // handle received messages
        //processor.ProcessMessageAsync += args => MessageHandler<T>(args,handleServiceBusMessage);
        processor.ProcessMessageAsync += args => MessageStringHandler(args, handleServiceBusMessage);
        processor.ProcessErrorAsync += ErrorHandler;

        // Start processing
        await processor.StartProcessingAsync(cancellationToken);

        Console.WriteLine("Task running");

    }

    

    // handle received messages
    async Task MessageStringHandler(ProcessMessageEventArgs args, IHandleServiceBusMessage handleServiceBusMessage)
    {
        var body = args.Message.Body.ToString();
        Console.WriteLine($"Received: imageFileName {body}");

        await handleServiceBusMessage.HandleStringMessageAsync(body);

        // complete the message. messages are deleted from the subscription. 
        await args.CompleteMessageAsync(args.Message);
    }

    // handle any errors when receiving messages
    Task ErrorHandler(ProcessErrorEventArgs args)
    {
        Console.WriteLine(args.Exception.ToString());
        return Task.CompletedTask;
    }

}

错误:

System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'IServiceProvider'.
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ThrowHelper.ThrowObjectDisposedException()
   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 PostService.Factories.EventProcessorFactory.GetEventProcessorStrategy(IServiceProvider serviceProvider, EventType eventType) in /Users/dmata/Projects/InstagramSD/PostService/Factories/EventProcessorFactory.cs:line 31
   at PostService.TaskServices.LikeTopicConsumerTaskService.HandleStringMessageAsync(String message) in /Users/dmata/Projects/InstagramSD/PostService/TaskServices/LikeTopicConsumerTaskService.cs:line 54
   at Common.ServiceBus.ServiceBusConsumerBase.MessageStringHandler(ProcessMessageEventArgs args, IHandleServiceBusMessage handleServiceBusMessage) in /Users/dmata/Projects/InstagramSD/Common/ServiceBus/ServiceBusConsumerBase.cs:line 59
   at Azure.Messaging.ServiceBus.ServiceBusProcessor.OnProcessMessageAsync(ProcessMessageEventArgs args)
   at Azure.Messaging.ServiceBus.ReceiverManager.OnMessageHandler(EventArgs args)