做电影网站侵权吗,crm系统 网站建设,建行个人网上登录入口,兰州seo实战优化微软官方的开源项目eShopOnContainers中#xff0c;用到了一个实现中介者模式的类库#xff1a;MediatR。这个类库的作者叫Jimmy Bogard#xff0c;在其gtihub主页上可以看到#xff0c;注明的对象映射组件AutoMapper 就是他写的。其博客上的自我介绍是这么写的#xff1a… 微软官方的开源项目eShopOnContainers中用到了一个实现中介者模式的类库MediatR。这个类库的作者叫Jimmy Bogard在其gtihub主页上可以看到注明的对象映射组件AutoMapper 就是他写的。其博客上的自我介绍是这么写的Headspring的首席架构师《MVC in Action》的作者国际演说家高产的开源软件开发者。擅长分布式系统REST消息领域驱动设计和CQRS。回到MediatR这个组件他是一个低调的类库致力于解决一个简单的问题解耦进程内消息的发送与处理。跨平台支持.NET4.5和netstandard1.1。中介者模式在继续研究MediatR之前先回顾下“中介者设计模式Mediator”中介者模式的定义为用一个中介对象来封装一系列的对象交互。中介者使各对象不需要显式地相互应用从而使其耦合松散而且可以独立地改变他们之间的交互。其结构图如下以下是一个具体的中介者模式demo/// summary
/// 抽象中介者
/// /summary
public abstract class AbstractMediator
{public abstract void SendMessage(string msg, AbstractColleague colleague);
}/// summary
/// 抽象同事类
/// /summary
public abstract class AbstractColleague
{public string Name { get; set; }protected AbstractMediator Mediator;protected AbstractColleague(AbstractMediator mediator){Mediator mediator;}public abstract void PrintMsg(string msg);
}/// summary
/// 具体中介者负责同事类之间的交互他必须清楚的知道需要交互的所有同事类的细节。
/// /summary
public class Mediator : AbstractMediator
{public AbstractColleague ColleagueA;public AbstractColleague ColleagueB;public override void SendMessage(string msg, AbstractColleague colleague){if (colleague ColleagueA){ColleagueB.PrintMsg(msg);}else if (colleague ColleagueB){ColleagueA.PrintMsg(msg);}}
}/// summary
/// 具体同事类A他是不知道其他具体同事类的存在的。他与其他同事类的交互是通过中介者来实现的。
/// /summary
public class ConcreteColleagueA : AbstractColleague
{public ConcreteColleagueA(AbstractMediator mediator) : base(mediator){}public void SendMessage(string msg){Mediator.SendMessage(msg,this);}public override void PrintMsg(string msg){Console.WriteLine($A收到消息{msg});}
}public class ConcreteColleagueB : AbstractColleague
{public ConcreteColleagueB(AbstractMediator mediator) : base(mediator){}public void SendMessage(string msg){Mediator.SendMessage(msg, this);}public override void PrintMsg(string msg){Console.WriteLine($B收到消息{msg});}
}class Program
{/// summary/// 客户端调用/// /summary/// param nameargs/paramstatic void Main(string[] args){var mediator new Mediator();var colleagueA new ConcreteColleagueA(mediator);var colleagueB new ConcreteColleagueB(mediator);mediator.ColleagueA colleagueA;mediator.ColleagueB colleagueB;colleagueA.SendMessage(你好B中午一起饭吧);colleagueB.SendMessage(你好A好的。);Console.ReadLine();}
}程序输出如下B收到消息你好B中午一起饭吧
A收到消息你好A好的。中介者类把不同的同事类之间的交互提升到其内部这样同事类之间的交互变得简单了同事类不需要知道其他同事类的存在通过中介者类来完成与其他同事类的交互。另一方面中介者类本身复杂性增加中介者类需要知道所有的同事类例如调用他们的公共方法。MediatRMediatR可以与很多依赖注入组件一起工作其github文档有详细说明。以下是我结合Autofac组件的代码研究。新建ASP.NET Core Console程序添加MediatR和Autofac依赖包。然后配置Autofacvar builder new ContainerBuilder();
// mediator itself
builder.RegisterTypeMediator().AsIMediator().InstancePerLifetimeScope();// request handlers
builder.RegisterSingleInstanceFactory(ctx {var c ctx.ResolveIComponentContext();return t c.TryResolve(t, out var o) ? o : null;}).InstancePerLifetimeScope();// notification handlers
builder.RegisterMultiInstanceFactory(ctx {var c ctx.ResolveIComponentContext();return t (IEnumerableobject)c.Resolve(typeof(IEnumerable).MakeGenericType(t));}).InstancePerLifetimeScope();//builder.RegisterTypePingHandler().AsImplementedInterfaces().InstancePerDependency();
builder.RegisterAssemblyTypes(typeof(Program).GetTypeInfo().Assembly).AsImplementedInterfaces();var mediator builder.Build().ResolveIMediator();
Test(mediator);MediatR可以支持几种模式有请求/响应模式发布模式。请求/响应模式也可以叫做命令模式主要适用于命令和查询场景。一个请求只能被一个处理者捕获如果存在多个处理者那么只有最后一个处理者会被激活。以下代码声明消息然后定义处理者/*注意请求/响应接口适用于命令和查询场景。*都只能有一个Handler如果注册多个只有最后一个会生效。*/
public class Ping : IRequeststring
{public int MsgId { get; set; }
}public class PingHandler : IRequestHandlerPing, string
{public Taskstring Handle(Ping request, CancellationToken cancellationToken){return Task.FromResult($MsgID{request.MsgId},Pong);}
}/// summary
/// 为了方便不需要CancellationToken的Handler可以继承AsyncRequestHandler类
/// /summary
public class AsyncNoCancellation : AsyncRequestHandlerPing, string
{protected override Taskstring HandleCore(Ping request){return Task.FromResult(Pong);}
}/// summary
/// 如果Handler是完全同步的可以继承RequestHandler类
/// /summary
public class SyncHandler : RequestHandlerPing, string
{protected override string HandleCore(Ping request){return $SyncHandler Pong;}
}然后就是发送请求了var response await mediator.Send(new Ping(){MsgId 100});
Console.WriteLine(response); // SyncHandler Pong另外请求/响应模式还支持不带任何返回值的处理者public class OneWay:IRequest
{public int MsgId { get; set; }
}public class OneWayHandler : IRequestHandlerOneWay
{public Task Handle(OneWay request, CancellationToken cancellationToken){Console.WriteLine(${request.MsgId},OneWayHandler);return Task.CompletedTask;}
}发布模式一般用于发布一个事件通知订阅者某件事情已经发生对此事感兴趣的订阅者可以采取行动了。一般是一个发布这多个订阅者。public class Hello : INotification
{public int MsgId { get; set; }
}public class Hello1 : INotificationHandlerHello
{public async Task Handle(Hello notification, CancellationToken cancellationToken){await Task.Delay(3000);Console.WriteLine(${notification.MsgId},{Thread.CurrentThread.ManagedThreadId});}
}public class Hello2 : INotificationHandlerHello
{public async Task Handle(Hello notification, CancellationToken cancellationToken){await Task.Delay(3000);Console.WriteLine(${notification.MsgId},{Thread.CurrentThread.ManagedThreadId});}
}像这样发布消息await mediator.Publish(new Hello() {MsgId 300});程序输出如下300,4
300,5
Main 5这里可以看到2个订阅者都被激活了。另外可以看到不同的订阅者所处的线程ID不一样他们是异步执行的。原文地址 http://coderyu.com/2018/04/02/mediatr-%E4%B8%AD%E4%BB%8B%E8%80%85/.NET社区新闻深度好文欢迎访问公众号文章汇总 http://www.csharpkit.com