EventBus事件总线（牛x版）

成员介绍：

IEventBus、EventBus：事件总线

IEventHandler、xxxEventHandler：事件处理程序

IEvent、xxxEvent：事件，一个事件可对应多个事件处理程序

EventHandlerAttribute：事件处理程序的特性，可添加排序信息等

EvnetHandlerMetadata：IEventHandler信息

EventHandlerMetadataItem：EventHandler实例信息

事件总线：

     public interface IEventBus

     {

         void Trigger<TEvent>(TEvent eventData, string topic = null) where TEvent : IEvent;

     }

     public class EventBus : IEventBus

     {

         private static System.Collections.Concurrent.ConcurrentDictionary<Type, EvnetHandlerMetadata> _evnetHandlerMetadatas

             = new ConcurrentDictionary<Type, EvnetHandlerMetadata>();

         private static readonly EventHandlerAttribute DefaultAttribute = new EventHandlerAttribute()

         {

             IgnoreError = false,

             Priority = ,

             Topic = null

         };

         static EventBus()

         { }

         public Func<Type, object> Activator { get; set; }

         /// <summary>

         /// 触发事件

         /// </summary>

         /// <typeparam name="IEvent"></typeparam>

         /// <param name="eventData"></param>

         public void Trigger<TEvent>(TEvent eventData, string topic = null) where TEvent : IEvent

         {

             EvnetHandlerMetadata evnetHandlerMetadata = _evnetHandlerMetadatas.GetOrAdd(typeof(TEvent), (key) =>

             {

                 var handlerType = typeof(IEventHandler<>).MakeGenericType(typeof(TEvent));

                 var handlerMetadata = new EvnetHandlerMetadata()

                 {

                     EventHandlerType = handlerType,

                     EventType = key,

                     Items = new List<EventHandlerMetadataItem>()

                 };

                 var handlerInstances = Activator.Invoke(typeof(IEnumerable<>).MakeGenericType(handlerType)) as IEnumerable;

                 foreach (var handlerInstance in handlerInstances)

                 {

                     var typeInfo = handlerInstance.GetType().GetTypeInfo();

                     var handleMethods = typeInfo.DeclaredMethods.Where(t => t.Name.EndsWith($"{key.Name}>.Handle") || t.Name == "Handle");

                     var method = handleMethods.FirstOrDefault();

                     if (method == null) continue;

                     var attr = method.GetCustomAttribute<EventHandlerAttribute>()

                         ?? handlerInstance.GetType().GetCustomAttribute<EventHandlerAttribute>()

                         ?? DefaultAttribute

                         ;

                     handlerMetadata.Items.Add(new EventHandlerMetadataItem()

                     {

                         Method = method,

                         IgnoreError = attr.IgnoreError,

                         Priority = attr.Priority,

                         Type = handlerInstance.GetType()

                     });

                 }

                 handlerMetadata.Items = handlerMetadata.Items.OrderByDescending(p => p.Priority).ThenBy(x => x.Type.Name).ToList();

                 return handlerMetadata;

             });

             var handlers = evnetHandlerMetadata.Items

                 .WhereIf(p => p.Topic == topic, !string.IsNullOrEmpty(topic))

                 .Select(x => new { Instance = Activator.Invoke(x.Type), Meta = x })

                 .ToList()

                 ;

             foreach (var handler in handlers)

             {

                 try

                 {

                     handler.Meta.Method.Invoke(handler.Instance, new object[] { eventData });

                 }

                 catch (Exception ex)

                 {

                     if (!handler.Meta.IgnoreError)

                     {

                         while (true)

                         {

                             if (ex.InnerException == null)

                             {

                                 throw ex;

                             }

                             else

                             {

                                 ex = ex.InnerException;

                             }

                         }

                     }

                 }

             }

         }

         public class EventHandlerMetadataItem

         {

             public Type Type { get; set; }

             public MethodInfo Method { get; set; }

             public int Priority { get; set; }

             public bool IgnoreError { get; set; }

             public string Topic { get; set; }

         }

         public class EvnetHandlerMetadata

         {

             public List<EventHandlerMetadataItem> Items { get; set; }

             public Type EventHandlerType { get; set; }

             public Type EventType { get; set; }

         }

     }

事件处理接口：

     /// <summary>

     /// 事件处理接口

     /// </summary>

     /// <typeparam name="TEvent">继承IEvent对象的事件源对象</typeparam>

     public interface IEventHandler<T> where T : IEvent

     {

         /// <summary>

         /// 处理程序

         /// </summary>

         /// <param name="evt"></param>

         void Handle(T evt);

     }

     [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = false)]

     public class EventHandlerAttribute : Attribute

     {

         /// <summary>

         /// 执行优先级

         /// </summary>

         public int Priority { get; set; }

         public bool IgnoreError { get; set; }

         public string Topic { get; set; }

         public EventHandlerAttribute()

         {

         }

     }

public interface IEvent
{
}

具体事件处理：

     /// <summary>

     /// 文件上传事件处理

     /// </summary>

     [EventHandler(Priority =, IgnoreError = true)]

     public class FileUploadEventHandler : IEventHandler<FileUploadEvent>

     {

         private readonly IFeeService _feeService;

         private readonly ILogger _logger;

         public FileUploadEventHandler(

             IFeeService feeService,

             ILogger<FileUploadEventHandler> logger

             )

         {

             _feeService = feeService;

             _logger = logger;

         }

         public void Handle(FileUploadEvent evt)

         {

            // _logger.LogInformation(evt.FileName);

             ////扣减存储空间

             //var useResult=_feeService.UseFeeItem(Enums.Finance_FeeItem.Storage, evt.FileSize, $"上传文件{evt.FileName}");

             //if (!useResult.Success)

             //{

             //    throw new Exception(useResult.Message);

             //}

         }

     }

事件触发：

var eventBus = _serviceLocator.GetService<IEventBus>();

eventBus.Trigger(new FileUploadEvent() { OwnUserID = globalValue.User.ID, UserID = globalValue.User.OwnUserID, Url = uploadResult.Data.Url, FileName = file.FileName, FileSize = file.Length, FileType = fileType });

参考：https://www.cnblogs.com/lwqlun/p/10468058.html

巴特西

EventBus事件总线（牛x版）

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