事件聚合器用于集中管理事件的订阅(Subscribe)和处理(Handle),要使用事件聚合器,首先要理解:事件(event)本质上是一个类。
传统的+=和-=不足:
1、管理很麻烦;2、不方便扩展。
所以尝试使用事件聚合器来解决这个问题。
首先,使用一个统一的接口来实现事件的统一标记:
public interface IEvent{ }
事件,需要有对应的事件处理器(EventHandler),这里使用一个统一的接口 IEventHandler 来进行统一,IEventHandler 只包含一个处理事件的方法 Handle
public interface IEventHandler<in TEvent> where TEvent: class, IEvent { void Handler(TEvent @event); }
事件聚合器接口 IEventAggregator 需要包含至少两个方法:订阅(Subscribe)和发布(Publish)
public interface IEventAggregator { void Subscribe<TEvent>(IEventHandler<TEvent> handler) where TEvent : class, IEvent; void Publish<TEvent>(TEvent @event) where TEvent : class, IEvent; }
接下来是实现这个接口:EventAggregator
举例:
using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace EventAggregatorTest { public interface IEvent { } public interface IEventHandler<in TEvent> where TEvent : class, IEvent { void Handler(TEvent @event); } public interface IEventAggregator { void Subscribe<TEvent>(IEventHandler<TEvent> handler) where TEvent : class, IEvent; void Publish<TEvent>(TEvent @event) where TEvent : class, IEvent; } public class EventAggregator : IEventAggregator { // 所有的 event 和 对应的 handler 都注册在这个字典里 private readonly Dictionary<Type, List<object>> _eventHandlers = new Dictionary<Type, List<object>>(); public void Subscribe<TEvent>(IEventHandler<TEvent> handler) where TEvent : class, IEvent { var eventType = typeof(TEvent); if (_eventHandlers.ContainsKey(eventType)) { var handlers = _eventHandlers[eventType]; if (handlers != null) { handlers.Add(handler); } else { handlers = new List<object> { handler }; } } else { _eventHandlers.Add(eventType, new List<object> { handler }); } } public void Publish<TEvent>(TEvent @event) where TEvent : class, IEvent { var eventType = @event.GetType(); if (_eventHandlers.ContainsKey(eventType) && _eventHandlers[eventType] != null && _eventHandlers[eventType].Count > 0) { var handlers = _eventHandlers[eventType]; foreach (var handler in handlers) { var eventHandler = handler as IEventHandler<TEvent>; eventHandler?.Handler(@event); } } } } public class MealDoneEvent : IEvent { public string DishName { get; private set; } public MealDoneEvent(string dishName) { DishName = dishName; } } public class MealDoneEventHandler : IEventHandler<MealDoneEvent> { private readonly string _name; public MealDoneEventHandler(string name) { _name = name; } #region Implementation of IEventHandler<in MealDoneEvent> public void Handler(MealDoneEvent @event) { Console.WriteLine($"{_name} 正在 {@event.DishName}"); } #endregion } }
调用:
using EventAggregatorTest; using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace EventAggregatorDemo { class Program { static void Main(string[] args) { var eventAggregator = new EventAggregator(); eventAggregator.Subscribe(new MealDoneEventHandler("张三")); eventAggregator.Subscribe(new MealDoneEventHandler("李四")); eventAggregator.Subscribe(new MealDoneEventHandler("王五")); eventAggregator.Publish(new MealDoneEvent("吃大餐")); Console.ReadKey(); } } }
时间: 2024-10-15 02:05:54