ASP.NET Core 1.0借鑒了Katana項目的管道設計(Pipeline)。日志記錄、用戶認證、MVC等模塊都以中間件(Middleware)的方式注冊在管道中。顯而易見這樣的設計非常松耦合并且非常靈活，你可以自己定義任意功能的Middleware注冊在管道中。這一設計非常適用于“請求-響應”這樣的場景——消息從管道頭流入最后反向流出。

在本文中暫且為這種模式起名叫做“管道-中間件（Pipeline-Middleware)”模式吧。

本文將描述”管道-中間件模式”的“契約式”設計和“函數式”設計兩種方案。

一、什么是管道-中間件模式？

在此模式中抽象了一個類似管道的概念，所有的組件均以中間件的方式注冊在此管道中，當請求進入管道后：中間件依次對請求作出處理，然后從最后一個中間件開始處理響應內容，最終反向流出管道。

二、契約式設計

契約式設計是從面向對象的角度來思考問題，根據管道-中間件的理解，中間件(Middleware)有兩個職責：

1 2 3 4 5

public? interface? IMiddleware { ???? Request ProcessRequest(Request request); ???? Response ProcessResponse(Response response); }

管道(Pipeline)抽象應該能夠注冊中間件(Middleware)：

1 2 3 4 5 6 7 8 9

public? interface? IApplicationBuilder { ???? void? Use(IMiddleware middleware); ???? void? UseArrange(List<IMiddleware> middlewares); ???? Context Run(Context context); }

實現IApplicationBuilder：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 3 2 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49

public? class? ApplicationBuilder : IApplicationBuilder { ???? public? IWindsorContainer Container { get ; private? set ; } ???? private? readonly? List<IMiddleware> _middlewares; ???? public? ApplicationBuilder(IWindsorContainer container) ???? { ???????? Contract.Requires(container!= null , "container!=null" ); ???????? _middlewares= new? List<IMiddleware>(); ???????? Container = container; ???? } ???? public? void? Use(IMiddleware middleware) ???? { ???????? Contract.Requires(middleware != null , "middleware!=null" ); ???????? _middlewares.Add(middleware); ???? } ???? public? void? UseArrange(List<IMiddleware> middlewares) ???? { ???????? Contract.Requires(middlewares != null , "middlewares!=null" ); ???????? _middlewares.AddRange(middlewares); ???? } ???? public? Context Run(Context context) ???? { ???????? Contract.Requires(context!= null , "context!=null" ); ???????? var? request=context.Request; ???????? var? response=context.Response; ???????? foreach? ( var? middleware in? _middlewares) ???????? { ???????????? request = middleware.ProcessRequest(request); ???????? } ???????? _middlewares.Reverse(); ???????? foreach? ( var? middleware in? _middlewares) ???????? { ???????????? response = middleware.ProcessResponse(response); ???????? } ???????? return? new? Context(request,response); ???? } }

Run()方法將依次枚舉Middleware并對消息的請求和響應進行處理，最后返回最終處理過的消息。

接下來需要實現一個Middleware：

1 2 3 4 5 6 7 8 9 10 11 12 13 14

public? class? DefaultMiddleware:IMiddleware ? { ????? public? Request ProcessRequest(Request request) ????? { ????????? request.Process( "default request" , "processed by defaultMiddleware" ); ????????? return? request; ????? } ????? public? Response ProcessResponse(Response response) ????? { ????????? response.Process( "default response" , "processed by defaultMiddleware" ); ????????? return? response; ????? } ? }

為了將Middleware注冊進管道，我們還可以寫一個擴展方法增加代碼的可讀性：

1 2 3 4 5 6 7 8 9 10 11 12

public? static? void? UseDefaultMiddleware( this? IApplicationBuilder applicationBuilder) { ???? applicationBuilder.Use<DefaultMiddleware>(); } public? static? void? Use<TMiddleware>( this? IApplicationBuilder applicationBuilder) ???? where? TMiddleware:IMiddleware { ???? var? middleware = applicationBuilder.Container.Resolve<TMiddleware>(); ???? applicationBuilder.Use(middleware); }

寫個測試看看吧：

寫第二個Middleware：

1 2 3 4 5 6 7 8 9 10 11 12 13 1 15 16

public? class? GreetingMiddleware:IMiddleware { ???? public? Request ProcessRequest(Request request) ???? { ???????? request.Process( "hello, request" , "processed by greetingMiddleware" ); ???????? return? request; ???? } ???? public? Response ProcessResponse(Response response) ???? { ???????? response.Process( "hello, request" , "processed by greetingMiddleware" ); ???????? return? response; ???? } }

編寫測試：

三、函數式設計方案

此方案也是Owin和ASP.NET Core采用的方案，如果站在面向對象的角度，第一個方案是非常清晰的，管道最終通過枚舉所有Middleware來依次處理請求。

站在函數式的角度來看，Middleware可以用Func<Context, Context>來表示，再來看看這張圖：

一個Middleware的邏輯可以用Func<Func<Context, Context>, Func<Context, Context>>來表示，整個Middleware的邏輯可以用下面的代碼描述：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

public? Func<Func<Context, Context>, Func<Context, Context>> Process() { ???? Func<Func<Context, Context>, Func<Context, Context>> middleware = next => ???? { ???????? Func<Context, Context> process = context => ???????? { ???????????? /*process request*/ ??????????? ???????????? next(context); ???????????? /*process response*/ ???????????? return? context; ???????? }; ???????? return? process; ???? }; ???? return? middleware; }

這一過程是理解函數式方案的關鍵，所有Middleware可以聚合為一個Func<Context,Context>,為了易于閱讀，我們可以定義一個委托：

1	public? delegate? Context RequestDelegate(Context context);

給定初始RequestDelegate，聚合所有Middleware：

1 2 3 4 5 6 7 8 9 10 11 1 13

public? IApplication Build() { ???? RequestDelegate request = context => context; ???? _middlewares.Reverse(); ???? foreach? ( var? middleware in? _middlewares) ???? { ???????? request = middleware(request); ???? } ???? return? new? Application(request); }

自定義一個函數式Middleware：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 8 19 20 21 22

public? class? DefaultMiddleware:IMiddleware { ???? public? Func<RequestDelegate, RequestDelegate> Request() ???? { ???????? Func<RequestDelegate, RequestDelegate> request = next => ???????? { ???????????? return? context => ???????????? { ???????????????? context.Request.Process( "default request" , "processed by defaultMiddleware" ); ???????????????? next(context); ???????????????? context.Response.Process( "default response" , "processed by defaultMiddleware" ); ???????????????? return? context; ???????????? }; ???????? }; ???????? return? request; ???? } }

所有代碼提供下載：https://git.oschina.net/richieyangs/Pipeline.Middleware.git

相關文章

• ASP.NET Core 1.0 入門——Application Startup

• ASP.NET Core 1.0 入門——了解一個空項目

• ASP.NET Core 1.0 部署 HTTPS （.NET Framework 4.5.1）

• .NET Core 1.0、ASP.NET Core 1.0和EF Core 1.0簡介

• 云服務器下ASP.NET Core 1.0環境搭建（包含mono與coreclr）

• 使用VS Code開發ASP.NET Core 應用程序

• dotnet run是如何啟動asp.net core站點的

• ASP.NET Core提供模塊化Middleware組件

• “dotnet restore"和"dotnet run"都做了些什么？

• 探秘 dotnet run 如何運行 .NET Core 應用程序

• .NET Portability Analyzer 已開源

• .NET跨平臺之旅：corehost 是如何加載 coreclr 的

• ASP.NET Core 行軍記 -----拔營啟程

• 如何遷移#SNMP到.NET Core平臺的一些體會

原文地址：http://www.cnblogs.com/richieyang/p/5315390.html

---

.NET社區新聞，深度好文，微信中搜索dotNET跨平臺或掃描二維碼關注

總結

以上是生活随笔為你收集整理的ASP.NET Core 1.0中的管道-中间件模式的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。