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lang: ja-jp
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# ASP.NET Core Webアプリ Hello World　2021-05-10

> Web アプリケーション コードを準備する
> https://docs.microsoft.com/ja-jp/learn/modules/host-a-web-app-with-azure-app-service/4-implement-a-web-app?pivots=csharp

## 作成可能なテンプレートの一覧表示

$ dotnet new -l
Templates                                     Short Name           Language    Tags
--------------------------------------------  -------------------  ----------  ----------------------
Console Application                           console              [C#],F#,VB  Common/Console
Class library                                 classlib             [C#],F#,VB  Common/Library
WPF Application                               wpf                  [C#]        Common/WPF
WPF Class library                             wpflib               [C#]        Common/WPF
WPF Custom Control Library                    wpfcustomcontrollib  [C#]        Common/WPF
WPF User Control Library                      wpfusercontrollib    [C#]        Common/WPF
Windows Forms (WinForms) Application          winforms             [C#]        Common/WinForms
Windows Forms (WinForms) Class library        winformslib          [C#]        Common/WinForms
Worker Service                                worker               [C#],F#     Common/Worker/Web
Unit Test Project                             mstest               [C#],F#,VB  Test/MSTest
NUnit 3 Test Project                          nunit                [C#],F#,VB  Test/NUnit
NUnit 3 Test Item                             nunit-test           [C#],F#,VB  Test/NUnit
xUnit Test Project                            xunit                [C#],F#,VB  Test/xUnit
Razor Component                               razorcomponent       [C#]        Web/ASP.NET
Razor Page                                    page                 [C#]        Web/ASP.NET
MVC ViewImports                               viewimports          [C#]        Web/ASP.NET
MVC ViewStart                                 viewstart            [C#]        Web/ASP.NET
Blazor Server App                             blazorserver         [C#]        Web/Blazor
Blazor WebAssembly App                        blazorwasm           [C#]        Web/Blazor/WebAssembly
ASP.NET Core Empty                            web                  [C#],F#     Web/Empty
ASP.NET Core Web App (Model-View-Controller)  mvc                  [C#],F#     Web/MVC
ASP.NET Core Web App                          webapp               [C#]        Web/MVC/Razor Pages
ASP.NET Core with Angular                     angular              [C#]        Web/MVC/SPA
ASP.NET Core with React.js                    react                [C#]        Web/MVC/SPA
ASP.NET Core with React.js and Redux          reactredux           [C#]        Web/MVC/SPA
Razor Class Library                           razorclasslib        [C#]        Web/Razor/Library
ASP.NET Core Web API                          webapi               [C#],F#     Web/WebAPI
ASP.NET Core gRPC Service                     grpc                 [C#]        Web/gRPC
dotnet gitignore file                         gitignore                        Config
global.json file                              globaljson                       Config
NuGet Config                                  nugetconfig                      Config
Dotnet local tool manifest file               tool-manifest                    Config
Web Config                                    webconfig                        Config
Solution File                                 sln                              Solution
Protocol Buffer File                          proto                            Web/gRPC

## 「ASP.NET Core Empty」プロジェクトを作成

$ dotnet new web --name web_sample001

## Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace web_sample001
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}

## Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace web_sample001
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapGet("/", async context =>
                {
                    context.Response.Headers.Add("Content-Type", "text/plain; charset=utf-8");
                    await context.Response.WriteAsync("こんにちは　世界！！");
                });
            });
        }
    }
}

## 実行

$ dotnet run


###### tags: `ASP.NET Core` `Webアプリ` `Hello World`