000.Introduction to ASP.NET Core

Introduction to ASP .NET Core

Asp.net core 介绍

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By Daniel Roth, Rick Anderson and Shaun Luttin

Meng.Net 自译

ASP.NET Core is a significant redesign of ASP.NET. This topic introduces the new concepts in ASP.NET Core and explains how they help you

Asp.net core 是 asp.net 的重大重构版本 , 本文介绍asp.net core新的概念,并且解释你怎样

develop modern web apps.

开发现代web 应用.

Sections:

What is ASP.NET Core?
Why build ASP.NET Core?
Application anatomy
Startup
Services
Middleware
Servers
Content root
Web root
Configuration
Environments
Build web UI and web APIs using ASP.NET Core MVC
Client-side development
Next steps

What is ASP.NET Core

ASP.NET Core is a new open-source and cross-platform framework for building modern cloud based internet connected applications, such as

Asp.net core 是一个新的 ,开源的,跨平台的框架, 可用来构建现代的,基于云连接的应用程序,例如:

web apps, IoT apps and mobile backends. ASP.NET Core apps can run on .NET Core or on the full .NET Framework. It was architected to

web应用,物联网应用,移动后台. Asp.net core 程序可以运行在.net core 或者 .net framework 上. 它被构建

provide an optimized development framework for apps that are deployed to the cloud or run on-premises. It consists of modular components

提供一个最优化的应用开发框架,可以部署在云或运行在本地. 它由最小限度模块化组件

with minimal overhead, so you retain flexibility while constructing your solutions. You can develop and run your ASP.NET Core apps cross-

构成. 因此构建程序时你可以保持灵活性. 你可以跨平台开发/运行你的asp.net core 应用在

platform on Windows, Mac and Linux. ASP.NET Core is open source at GitHub.

Windows /mac /linux 系统, asp.net core 在github 上是开源的 .

Why build ASP.NET Core

The first preview release of ASP.NET came out almost 15 years ago as part of the .NET Framework. Since then millions of developers have

作为.net framework 的一部分, 第一个asp.net 预览已放发布超过15年了 . 从此,数百万的开发者

used it to build and run great web apps, and over the years we have added and evolved many capabilities to it.

用它构建/运行伟大的web应用, 并且在这些年中我们给他新增并扩展了很多功能.

ASP.NET Core has a number of architectural changes that result in a much leaner and modular framework. ASP.NET Core is no longer based on

Asp.net core 有一些结构设计上的改变,使得其高度简洁,模块化. Asp.net core 不在基于 system.web.dll .

System.Web.dll. It is based on a set of granular and well factored NuGet packages. This allows you to optimize your app to include just the

它基于一个细粒度的 / 因素分解的 nuget 包集合 . 这样你就可以优化你的应用,使其仅包含

NuGet packages you need. The benefits of a smaller app surface area include tighter security, reduced servicing, improved performance, and

你需要的 nuget 文件. 好处是一个小的引用但是包含了安全/低耗/演进/

decreased costs in a pay-for-what-you-use model.

降低你的花费开销.

With ASP.NET Core you gain the following foundational improvements:

使用 asp.net core 你获得了以下基本的改进:

A unified story for building web UI and web APIs

一个构建 web UI / web api 的统一模式

Integration of modern client-side frameworks and development workflows

集成现代的客户端框架及开发流程

A cloud-ready environment-based configuration system

一个基于云的环境配置系统

Built-in dependency injection

内嵌依赖注入 DI

New light-weight and modular HTTP request pipeline

新的轻量级的 / 模块化的 http 请求管道

Ability to host on IIS or self-host in your own process

可以宿主与iis 或者自宿主

Built on .NET Core, which supports true side-by-side app versioning

以 .net core 作为基础, 支持并行版本控制

Ships entirely as NuGet packages

完全以 nuget 包作为承载

New tooling that simplifies modern web development

新的工具简化现代web开发

Build and run cross-platform ASP.NET apps on Windows, Mac and Linux

编译并跨平台运行,在 windows/mac/linux 系统上

Open source and community focused

开源/开源社区,支持的

Application anatomy

应用程序解析

An ASP.NET Core app is simply a console app that creates a web server in its Main method:

一个asp.net core 应用,是一个简单的控制台应用在它的main方法中创建的web服务.

 1 using System; 2 using Microsoft.AspNetCore.Hosting; 3  4 namespace aspnetcoreapp 5 { 6   public class Program 7   { 8     public static void Main(string[] args) 9     {10       var host = new WebHostBuilder()11         .UseKestrel()12         .UseStartup<Startup>()13         .Build();14 15       host.Run();16     }17   }18 }

Program.cs

Main uses WebHostBuilder, which follows the builder pattern, to create a web application host. The builder has methods that define the web server

Main 方法使用 WebHostBuilder 创建了一个 Host 。 WebHostBuilder 中定义了创建web服务器（Kestrel）的方法。

(for example UseKestrel) and the startup class (UseStartup). In the example above, the Kestrel web server is used, but other web servers can be

在上面的例子中，指定使用了 Kestrel 服务器，同时也可以指定使用其它的服务器（如IIS）。

specified. We’ll show more about UseStartup in the next section. WebHostBuilder provides many optional methods including UseIISIntegration for

关于 Startup 我们在下面的章节中将会讲解更多。WebHostBuilder 类提供了很多可选方法，如 UseIISIntegration（）可以使用IIS宿主

hosting in IIS and IIS Express and UseContentRoot for specifying the root content directory. The Build and Run methods build the IWebHost that

程序，UseContentRoot（）提供根目录。Build（）创建热点

will host the app and start it listening for incoming HTTP requests.

Run（）将开始监听程序的 HTTP 请求。

Startup

The UseStartup method on WebHostBuilder specifies the Startup class for your app.

WebHostBuilder 类 UseStartup（）方法使用你在程序中指定的 Startup 类。

 1 public class Program 2 { 3   public static void Main(string[] args) 4   { 5     var host = new WebHostBuilder() 6       .UseKestrel() 7       .UseStartup<Startup>() 8       .Build(); 9 10     host.Run();11   }12 }

Program.cs

The Startup class is where you define the request handling pipeline and where any services needed by the app are configured. The Startup class

在 Startup 类中你将定义请求处理管道和注册配置应用所需的服务。

must be public and contain the following methods:

Startup 类必须是 public 的，并且包含下面两个方法：

 1 public class Startup 2 { 3   public void ConfigureServices(IServiceCollection services) 4   { 5   } 6  7   public void Configure(IApplicationBuilder app) 8   { 9   }10 }

Startup.cs

ConfigureServices defines the services (see Services below) used by your app (such as the ASP.NET MVC Core framework, Entity Framework

　　ConfigureServices（）定义了应用中需要的服务，如：ASP.NET MVC Core、Entity Framework Core、Identity 等等。

Core, Identity, etc.)

Configure defines the middleware in the request pipeline

　　Configure（）定义了请求管道中的中间件。

See Application Startup for more details

Services

A service is a component that is intended for common consumption in an application. Services are made available through dependency injection.

service 是一种在应用中被用来公共使用的组件。服务（Services）通过依赖注入（DI）的方式使用。

ASP.NET Core includes a simple built-in inversion of control (IoC) container that supports constructor injection by default, but can be easily

Asp.net core 内置了IOC 容器，这个容器默认使用构造函数注入的方式，他可以简易的替换掉你自己选择的第三方IOC容器。

replaced with your IoC container of choice. In addition to its loose coupling benefit, DI makes services available throughout your app. For

除了松耦合的好处外，DI 让 services 在你的整个应用程序过程中都有效，

example, Logging is available throughout your app. See Dependency Injection for more details.

如：Logging 。

Middleware

In ASP.NET Core you compose your request pipeline using Middleware. ASP.NET Core middleware performs asynchronous logic on an

在 asp.net core 中，你将用中间件组成你的请求管道。中间件在 HttpContext 中将异步调用执行，一个执行完后会按顺序执行下一个

HttpContext and then either invokes the next middleware in the sequence or terminates the request directly. You generally “Use” middleware by

或者直接终止退出请求。你通常会这样使用中间件：

taking a dependency on a NuGet package and invoking a corresponding UseXYZ extension method on the IApplicationBuilder in the Configure

在Configure（）中 IApplicationBuilder 实例上使用形如 UseXYZ 的扩展方法。

method.

ASP.NET Core comes with a rich set of prebuilt middleware:

Asp.net core 官方提供了一组可用的中间件：

Static files
Routing
Authentication

You can also author your own custom middleware.

同样，你也可以自定义你自己的中间件。

You can use any OWIN-based middleware with ASP.NET Core. See Open Web Interface for .NET (OWIN) for details.

Servers

The ASP.NET Core hosting model does not directly listen for requests; rather it relies on an HTTP server implementation to forward the request

Asp.net core 的host 模块不会直接监听请求；当然了，它依赖于一个 HTTP server 的实现。

to the application. The forwarded request is wrapped as a set of feature interfaces that the application then composes into an HttpContext.

实现类转递过来的请求按照借口约定组装进 HttpContext 中。

ASP.NET Core includes a managed cross-platform web server, called Kestrel, that you would typically run behind a production web server like

Asp.net core 包含一个被托管的、跨平台的web服务器（Kestrel），就像iis 或 nginx 一样。

IIS or nginx.

Content root

The content root is the base path to any content used by the app, such as its views and web content. By default the content root is the same as

根目录（The content root）是应用中所有内容的根目录，如 views 。默认情况下，

application base path for the executable hosting the app; an alternative location can be specified with WebHostBuilder.

它与宿主app执行的应用根目录相同；也可用 WebHostBuilder 指定。

Web root

The web root of your app is the directory in your project for public, static resources like css, js, and image files. The static files middleware will

The web root 目录是你应用中静态资源文件（css、js）等的根目录。

only serve files from the web root directory (and sub-directories) by default. The web root path defaults to <content root>/wwwroot, but you can

默认情况下，静态资源中间件只有在文件从web root 目中请求时才服务。默认情况下 The web root 的路径是

specify a different location using the WebHostBuilder.

<content root>/wwwroot ，同时此路径你也可以在WebHostBuilder 中另外指定不同的路径。

Configuration

ASP.NET Core uses a new configuration model for handling simple name-value pairs. The new configuration model is not based on

Asp.ent core 用了一个新的配置处理模块来处理简单的键-值对。新的配置处理模块不再基于 System.Configuration

System.Configuration or web.config; rather, it pulls from an ordered set of configuration providers. The built-in configuration providers support a

与 web.config ；当然，它从配置提供程序中拉去。内置的配置提供程序支持

variety of file formats (

多种类型的文件（

custom configuration providers.

自定义的配置提供程序。

See Configuration for more information.

Environments

Environments, like “Development” and “Production”, are a first-class notion in ASP.NET Core and can be set using environment variables. See

像 Development 、 Production 环境，在 asp.net core 中是一种优秀的概念，并且是可配置使用的环境变量。

Working with Multiple Environments for more information.

Build web UI and web APIs using ASP.NET Core MVC

You can create well-factored and testable web apps that follow the Model-View-Controller (MVC) pattern. See MVC and Testing.
You can build HTTP services that support multiple formats and have full support for content negotiation. See Formatting Response Data
Razor provides a productive language to create Views
Tag Helpers enable server-side code to participate in creating and rendering HTML elements in Razor files
You can create HTTP services with full support for content negotiation using custom or built-in formatters (JSON,

用完全受支持的，使用内置或自定义的json 格式化器创建自定义的 http 服务

Model Binding automatically maps data from HTTP requests to action method parameters
Model Validation automatically performs client and server side validation

Client-side development

ASP.NET Core is designed to integrate seamlessly with a variety of client-side frameworks, including AngularJS, KnockoutJS and Bootstrap.

Asp.net core 从设计上无缝集成了客户端开发框架，包括：AngularJS、KnockoutJS 、Bootstrap 。

See Client-Side Development for more details.

Next steps