如何在 prism (eventaggregator) 中创建事件订阅者

Question

我的项目中有一个反复出现的模式。

我有发布 eventtaggregator-events 的命令，我有明确订阅事件并处理它们的类。

问题：过去，我从我的应用程序根对象中引用了每个事件处理程序，以确保它们被创建并因此能够“实时”捕获事件。有没有办法让我不必对每个事件处理类都这样做？ 所有事件处理程序都命名为 *EventHandler，如果可以使用的话...

我将 Unity 用于 IOC 容器。

感谢您的任何意见，

安德斯，丹麦

    public class PickWishListCommand : BaseCommand, IPickWishListCommand
    {
        private readonly IEventAggregator _eventAggregator;

        public PickWishListCommand(IEventAggregator eventAggregator)
        {
            _eventAggregator = eventAggregator;
        }

        public bool CanExecute(object parameter)
        {
            return true;
        }

        public void Execute(object parameter)
        {
            _eventAggregator
                .GetEvent<PickWishListEvent>()
                .Publish(parameter);
        }
    }

    public class PickWishListEventHandler : IPickWishListEventHandler
    {
        public PickWishListEventHandler(IEventAggregator eventAggregator)
        {
            eventAggregator.GetEvent<PickWishListEvent>().Subscribe(OnEvent);
        }

        private void OnEvent(object obj)
        {
            throw new System.NotImplementedException();
        }
    }

public partial class App
{
    protected override void OnStartup(StartupEventArgs e)
    {
        base.OnStartup(e);

        var container = new UnityContainer();
        container
            .RegisterTypes(
                AllClasses.FromAssembliesInBasePath(),
                WithMappings.FromMatchingInterface,
                WithName.Default,
                WithLifetime.ContainerControlled);

        var executionContext = container.Resolve<IExecutionContext>();
        var configurationApplicationService = container.Resolve<IConfigurationApplicationService>();

        configurationApplicationService.SetupMainWindow();

        //Thread.Sleep(3000);
        var mainWindow = new MainWindow
        {
            DataContext = executionContext.MainWindowViewModel
        };
        mainWindow.Show();
    }
}

编辑：我找到了一种自动实例化的方法——但要保持问题的开放性；可以做得更优雅吗？

     protected override void OnStartup(StartupEventArgs e)
        {
            base.OnStartup(e);

            var container = new UnityContainer();
            container
                .RegisterTypes(
                    AllClasses.FromAssembliesInBasePath(),
                    WithMappings.FromMatchingInterface,
                    WithName.Default,
                    WithLifetime.ContainerControlled);

            var eventHandlers = new List<object>();

            foreach (var registration in container.Registrations)
            {
                var nameOfRegType = registration.RegisteredType.Name;
                var overrides = new ResolverOverride[] { };
                if (!nameOfRegType.EndsWith("EventHandler") || !nameOfRegType.StartsWith("I")) continue;

                var t = container.Resolve(registration.RegisteredType, overrides);
                eventHandlers.Add(t);
            }
            var executionContext = container.Resolve<IExecutionContext>();
            executionContext.EventHandlers = eventHandlers;

            var configurationApplicationService = executionContext.ConfigurationApplicationService;
            configurationApplicationService.SetupMainWindow();

            var mainWindow = new MainWindow
            {
                DataContext = executionContext.MainWindowViewModel
            };

            mainWindow.Show();
        }

Answer 1

只是为了用一些代码澄清我的评论，当我使用 Prism EventAggregator 时，它将采用以下方式：

// A library class holding event classes
public class ThisClassDefinesMyEvents
{
  public class MyImportantEvent : CompositePresentationEvent<string>{};
}

// An example viewmodel, that subscribes to an event
public class SomeRecievingVm
{
  private readonly IEventAggregator _eventAggregator;
  public SomeRecievingVm(IEventAggregator eventAggregator)
  {
    _eventAggregator = eventAggregator;
    _eventAggregator.GetEvent<MyImportantEvent>().Subscribe(MyEventHandlingMethod);
  }

  public void MyEventHandlingMethod(string whatHappened)
  {
    Console.WriteLine(whatHappened);
  }
}

// An example VM that publishes an event, under a couple of different circumstances
public class SomeSendingVm
{
  private readonly IEventAggregator _eventAggregator;
  public SomeSendingVm(IEventAggregator eventAggregator)
  {
    _eventAggregator = eventAggregator;
    _eventAggregator.GetEvent<MyImportantEvent>().Publish("I am alive");
  }

  private void SomeMethodThatHappensSometimes()
  {
    _eventAggregator.GetEvent<MyImportantEvent>().Publish("I've done something");
  }
}