https://www.cnblogs.com/tanmingchao/p/9681975.html
本文轉(zhuǎn)自
[1.MediatR 是什么？
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<pre>微軟官方eshopOnContainer開源項(xiàng)目中使用到了該工具，
mediatR 是一種中介工具，解耦了消息處理器和消息之間耦合的類庫，支持跨平臺(tái) .net Standard和.net framework
https://github.com/jbogard/MediatR/wiki 這里是原文地址。其作者就是Automapper的作者。
功能要是簡(jiǎn)述的話就倆方面：
request/response 請(qǐng)求響應(yīng)
pub/sub 發(fā)布訂閱</pre>
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2.****使用
<pre>nuget: install-package MediatR
MediatR沒有其他的依賴項(xiàng)，您需要配置一個(gè)工廠委托,用來實(shí)例化所有處理程序、管道的行為,和前/后處理器。</pre>
[3.Autofac完整的IOC注入示例：
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<pre>// uncomment to enable polymorphic dispatching of requests, but note that // this will conflict with generic pipeline behaviors // builder.RegisterSource(new ContravariantRegistrationSource()); // mediator itself
builder
.RegisterType<Mediator>()
.As<IMediator>()
.InstancePerLifetimeScope(); // request handlers
builder
.Register<SingleInstanceFactory>(ctx => { var c = ctx.Resolve<IComponentContext>(); return t => c.TryResolve(t, out var o) ? o : null;
})
.InstancePerLifetimeScope(); // notification handlers
builder
.Register<MultiInstanceFactory>(ctx => { var c = ctx.Resolve<IComponentContext>(); return t => (IEnumerable<object>)c.Resolve(typeof(IEnumerable<>).MakeGenericType(t));
})
.InstancePerLifetimeScope(); // finally register our custom code (individually, or via assembly scanning) // - requests & handlers as transient, i.e. InstancePerDependency() // - pre/post-processors as scoped/per-request, i.e. InstancePerLifetimeScope() // - behaviors as transient, i.e. InstancePerDependency()
builder.RegisterAssemblyTypes(typeof(MyType).GetTypeInfo().Assembly).AsImplementedInterfaces(); // via assembly scan //builder.RegisterType<MyHandler>().AsImplementedInterfaces().InstancePerDependency(); // or individually</pre>
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[4.ASP.NET CORE 使用 IOC注入：
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<pre>引用 MediatR nuget:install-package MediatR
引用IOC擴(kuò)展 nuget:installpackage MediatR.Extensions.Microsoft.DependencyInjection
使用方式：
services.AddMediatR(typeof(MyHandler));
或
services.AddMediatR(typeof(Startup).GetTypeInfo().Assembly);
目的是為了掃描Handler的實(shí)現(xiàn)對(duì)象并添加到IOC的容器中</pre>
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5.參考示例
[5.1 請(qǐng)求響應(yīng)(request/response)，三步：
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<pre>步驟一：創(chuàng)建一個(gè)消息對(duì)象，需要實(shí)現(xiàn)IRequest,或IRequest<>接口，表明該對(duì)象是處理器的一個(gè)對(duì)象 public class Ping : IRequest<string> { }
步驟二：創(chuàng)建一個(gè)處理器對(duì)象 public class PingHandler : IRequestHandler<Ping, string> { public Task<string> Handle(Ping request, CancellationToken cancellationToken) { return Task.FromResult("Pong"); } }
步驟三：最后，通過mediator發(fā)送一個(gè)消息 var response = await mediator.Send(new Ping()); Debug.WriteLine(response); // "Pong"</pre>
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說明：如果某些情況下，如果你的消息發(fā)送不需要返回響應(yīng)結(jié)果的話，可以使用AsyncRequestHandler<TRequest>
參考實(shí)現(xiàn)：
<pre>public class OneWay : IRequest { } public class OneWayHandlerWithBaseClass : AsyncRequestHandler<OneWay> { protected override Task Handle(OneWay request, CancellationToken cancellationToken) { // Twiddle thumbs } }</pre>
或者需要異步實(shí)現(xiàn)可以使用 RequestHandler
參考實(shí)現(xiàn)：
<pre>public class SyncHandler : RequestHandler<Ping, string> { protected override string Handle(Ping request) { return "Pong"; } }</pre>
[5.1.1 Request的類型說明，比較幼稚了，，
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<pre>IRequest<T> 有返回值
IRequest 無返回值
IRequestHandler<T> 該對(duì)象的實(shí)現(xiàn)對(duì)象返回一個(gè) Task 對(duì)象
AsyncRequestHandler<T> 該對(duì)象的子對(duì)象（繼承）返回一個(gè) Task 對(duì)象
RequestHandler<T> 該對(duì)象的子對(duì)象（繼承） 無返回值
IRequestHandler<T,U> 該對(duì)象的實(shí)現(xiàn)對(duì)象返回一個(gè) Task<U> 對(duì)象
RequestHandler<T,U> 該對(duì)象的子對(duì)象（繼承）返回一個(gè) U 對(duì)象</pre>
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[5.2 Publishing,依舊三步走
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<pre>步驟一：創(chuàng)建一個(gè)用于通知的消息對(duì)象，實(shí)現(xiàn)INotification接口 public class Ping : INotification { }
步驟二：創(chuàng)建通知的處理器對(duì)象 public class Pong1 : INotificationHandler<Ping> {
public Task Handle(Ping notification, CancellationToken cancellationToken) { Debug.WriteLine("Pong 1"); return Task.CompletedTask; } }
public class Pong2 : INotificationHandler<Ping> { public Task Handle(Ping notification, CancellationToken cancellationToken) { Debug.WriteLine("Pong 2"); return Task.CompletedTask; } }
三步驟：最終使用mediator發(fā)布你的消息 await mediator.Publish(new Ping());</pre>
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5.3 其他：見github作者wiki參考示例
分類: .NET
