原文參考：

ASP.NET Web Api 2.2: Create a Self-Hosted OWIN-Based Web Api from Scratch

新建控制臺程序，引入Owin包

PM> Install-Package Microsoft.AspNet.WebApi.OwinSelfHost -Pre

添加Startup類

public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            var webApiConfiguration = ConfigureWebApi();

            
 
// Use the extension method provided by the WebApi.Owin library:
            app.UseWebApi(webApiConfiguration);
        }
        private HttpConfiguration ConfigureWebApi()
        {
            var config = new HttpConfiguration();
            config.Routes.MapHttpRoute(
                "DefaultApi
 
",
                "api/{controller}/{id}",
                new { id = RouteParameter.Optional });
            return config;
        }
    }

添加Models、Controllers文件夾，添加Company、CompaniesController

public class Company
    {
        [Key]
        public int Id { get; set; }
        public string Name { get
 
; set; }
    }

public class CompaniesController : ApiController
    {
        ApplicationDbContext _Db = new ApplicationDbContext();
        public IEnumerable<Company> Get()
        {
            return _Db.Companies;
        }


        public async Task<Company> Get(int id)
        {
            var company = await _Db.Companies.FirstOrDefaultAsync(c => c.Id == id);
            if (company == null)
            {
                throw new HttpResponseException(
                    System.Net.HttpStatusCode.NotFound);
            }
            return company;
        }


        public async Task<IHttpActionResult> Post(Company company)
        {
            if (company == null)
            {
                return BadRequest("Argument Null");
            }
            var companyExists = await _Db.Companies.AnyAsync(c => c.Id == company.Id);

            if (companyExists)
            {
                return BadRequest("Exists");
            }

            _Db.Companies.Add(company);
            await _Db.SaveChangesAsync();
            return Ok();
        }


        public async Task<IHttpActionResult> Put(Company company)
        {
            if (company == null)
            {
                return BadRequest("Argument Null");
            }
            var existing = await _Db.Companies.FirstOrDefaultAsync(c => c.Id == company.Id);

            if (existing == null)
            {
                return NotFound();
            }

            existing.Name = company.Name;
            await _Db.SaveChangesAsync();
            return Ok();
        }


        public async Task<IHttpActionResult> Delete(int id)
        {
            var company = await _Db.Companies.FirstOrDefaultAsync(c => c.Id == id);
            if (company == null)
            {
                return NotFound();
            }
            _Db.Companies.Remove(company);
            await _Db.SaveChangesAsync();
            return Ok();
        }
    }

添加EntityFramework包，添加ApplicationDbContext

namespace ConsoleWebApi.Models
{
    public class ApplicationDbContext : DbContext
    {
        public ApplicationDbContext() : base("MyDatabase")
        {
        }
        public IDbSet<Company> Companies { get; set; }
    }


    public class ApplicationDbInitializer : DropCreateDatabaseAlways<ApplicationDbContext>
    {
        protected override void Seed(ApplicationDbContext context)
        {
            base.Seed(context);
            context.Companies.Add(new Company { Name = "Microsoft" });
            context.Companies.Add(new Company { Name = "Google" });
            context.Companies.Add(new Company { Name = "Apple" });
        }
    }
}

App.Config中添加連接字符串

<connectionStrings>
    <add name="MyDatabase" connectionString="Data Source=.;Initial Catalog=Test;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=True;ApplicationIntent=ReadWrite;MultiSubnetFailover=False" providerName="System.Data.SqlClient"/>
  </connectionStrings>

入口Main中添加代碼

static void Main(string[] args)
        {
            Console.WriteLine("Initializing and seeding database...");
            Database.SetInitializer(new ApplicationDbInitializer());
            var db = new ApplicationDbContext();
            int count = db.Companies.Count();
            Console.WriteLine("Initializing and seeding database with {0} company records...", count);

            string baseUri = "http://localhost:8080";

            Console.WriteLine("Starting web Server...");
            WebApp.Start<Startup>(baseUri);
            Console.WriteLine("Server running at {0} - press Enter to quit. ", baseUri);
            Console.ReadLine();
        }

啟動程序，打開http://localhost:8080/api/companies/1

即可看到結果。

使用控制臺程序搭建WebApi