public class ConfirmEmailSentHandler : IEventHandler<ShoppingCartSubmittedEvent> { public void Run(ShoppingCartSubmittedEvent obj) { Console.WriteLine("Confirm Email Sent."); } public Task RunAsync(ShoppingCartSubmittedEvent obj) { return Task.Run(() => { Console.WriteLine("Confirm Email Sent."); }); } }
代码解释：
这个处理类非常简单，为了简化代码，我仅输出了一行文本来表示实际需要运行的代码。
为OrderManager类添加创建订单方法
IOrderManager.cs
public interface IOrderManager { string CreateNewOrder(CreateOrderDTO dto); }
OrderManager.cs
public class OrderManager : IOrderManager { private IOrderRepository _orderRepository; public OrderManager(IOrderRepository orderRepository) { _orderRepository = orderRepository; } public string CreateNewOrder(CreateOrderDTO dto) { var orderId = _orderRepository.CreatOrder(dto); Console.WriteLine($"One order created: {JsonConvert.SerializeObject(dto)}"); return orderId; } }
创建EventHandlerContainer
下面我们来编写最核心的事件处理器容器。在这里我们的事件处理器容器完成了3个功能
订阅事件(Subscribe Event)
取消订阅事件(Unsubscribe Event)
发布事件(Publish Event)
public class EventHandlerContainer { private IServiceProvider _serviceProvider = null; private static Dictionary<string, List<Type>> _mappings = new Dictionary<string, List<Type>>(); public EventHandlerContainer(IServiceProvider serviceProvider) { _serviceProvider = serviceProvider; } public static void Subscribe<T, THandler>() where T : EventBase where THandler : IEventHandler<T> { var name = typeof(T).Name; if (!_mappings.ContainsKey(name)) { _mappings.Add(name, new List<Type> { }); } _mappings[name].Add(typeof(THandler)); } public static void Unsubscribe<T, THandler>() where T : EventBase where THandler : IEventHandler<T> { var name = typeof(T).Name; _mappings[name].Remove(typeof(THandler)); if (_mappings[name].Count == 0) { _mappings.Remove(name); } } public void Publish<T>(T o) where T : EventBase { var name = typeof(T).Name; if (_mappings.ContainsKey(name)) { foreach (var handler in _mappings[name]) { var service = (IEventHandler<T>)_serviceProvider.GetService(handler); service.Run(o); } } } public async Task PublishAsync<T>(T o) where T : EventBase { var name = typeof(T).Name; if (_mappings.ContainsKey(name)) { foreach (var handler in _mappings[name]) { var service = (IEventHandler<T>)_serviceProvider.GetService(handler); await service.RunAsync(o); } } } }
代码解释：
这里我没有直接订阅事件处理器的实例，而且订阅了事件处理器的类型
多个事件处理器可以订阅同一个事件
EventHandlerContainer的构造函数中，我们注入了一个IServiceProvider，我们可以使用它来获得对应事件处理器的实例。
在程序启动时，注册事件订阅
现在我们来Startup.cs的ConfigureServices方法，这里我们需要进行服务注册，并完成事件订阅。
public void ConfigureServices(IServiceCollection services) { services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2); services.AddScoped<IOrderManager, OrderManager>(); services.AddScoped<IShoppingCartManager, ShoppingCartManager>(); services.AddScoped<IShoppingCartRepository, ShoppingCartRepository>(); services.AddScoped<IOrderRepository, OrderRepository>(); services.AddScoped<IUnitOfWork, UnitOfWork>(); services.AddScoped<CreateOrderHandler>(); services.AddScoped<ConfirmEmailSentHandler>(); services.AddScoped<EventHandlerContainer>(); EventHandlerContainer.Subscribe<ShoppingCartSubmittedEvent, CreateOrderHandler>(); EventHandlerContainer.Subscribe<ShoppingCartSubmittedEvent, ConfirmEmailSentHandler>(); }