首先创建一个空的web项目，如下图所示：
项目创建成功以后，安装下面三个package.
Install-Package Microsoft.AspNet.WebApi -Version 5.2.2
Install-Package Microsoft.AspNet.WebApi.Owin -Version 5.2.2
Install-Package Microsoft.Owin.Host.SystemWeb -Version 3.0.0
创建Owin Startup 类
1 using System;
2 using System.Threading.Tasks;
3 using Microsoft.Owin;
4 using Owin;
5 using System.Web.Http;
6
7 [assembly: OwinStartup(typeof(FirstOwinWebApi.Startup))]
8
9 namespace FirstOwinWebApi
10 {
11 public class Startup
12 {
13 public void Configuration(IAppBuilder app)
14 {
15 HttpConfiguration config = new HttpConfiguration();
16
17 // Web API routes
18 config.MapHttpAttributeRoutes();
19
20 //WebApiConfig.Register(config);
21
22 app.UseWebApi(config);
23 }
24 }
25 }
创建API Controller.
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Net;
5 using System.Net.Http;
6 using System.Web.Http;
7
8 namespace FirstOwinWebApi.Controllers
9 {
10 [RoutePrefix("api/HelloWorld")]
11 public class HelloWorldController : ApiController
12 {
13 [Route("")]
14 public IHttpActionResult Post()
15 {
16
17 return Ok<string>("Hello World");
18
19 }
20
21 }
22 }
F5运行，使用Postman访问Api
其他一些Owin中间件包：
Install-Package Microsoft.AspNet.WebApi -Version 5.2.2
Install-Package Microsoft.AspNet.WebApi.Owin -Version 5.2.2
Install-Package Microsoft.Owin.Host.SystemWeb -Version 3.0.0
Install-Package Microsoft.Owin.Cors -Version 3.0.0
Install-Package Microsoft.Owin.Security.OAuth -Version 3.0.0
Install-Package Microsoft.Owin.Security.Jwt -Version 3.0.0
Install-Package System.IdentityModel.Tokens.Jwt -Version 4.0.0
Install-Package Thinktecture.IdentityModel.Core Version 1.2.0
Install-Package Microsoft.AspNet.Identity.Owin -Version 2.0.1
Install-Package Microsoft.AspNet.Identity.EntityFramework -Version 2.0.1