OWIN 自宿主模式WebApi项目，WebApi层作为单独类库供OWIN调用

为什么我们需要OWIN

过去，IIS作为.NET开发者来说是最常用的Web Server（没有之一），源于微软产品的紧耦合关系，我们不得不将Website、Web Application、Web API等部署在IIS上，事实上在2010年前并没有什么不妥，但随着近些年来Web的发展，特别是移动互联网飞速发展，IIS作为Web Server已经暴露出他的不足了。主要体现在两个方面，ASP.NET (System.Web)紧耦合IIS，IIS紧耦合OS，这就意味着，我们的Web Framework必须部署在微软的操作系统上，难以跨平台。

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OWIN是什么？在本文里面就不进行赘述，网上有很多介绍OWIN的信息以及优缺点的博文，这里可以给几个链接大家进行自行参考：

1、http://www.cnblogs.com/dudu/p/what-is-owin.html

2、http://blog.csdn.net/hk_5788/article/details/51607211

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下面我们重点介绍我在搭建OWIN自宿主平台的过程，对于我是学习的过程，对于想要接触他的大家来说，也是一种帮助。

很多人搭建的OWIN+WebApi项目都是写在一个项目中的，我个人为了代码的隔离，将控制器层写在了另外一个项目中，这样有助于后期大型框架的形成。

下面是搭建步骤：

1、首先新建一个控制台应用程序和一个.NETFramework类库项目，控制台引用类库项目。

项目结构如下图所示：

OWIN.WebApi WebApi层

OWIN.WebApi.Sv WebApi服务层，将要作为启动项！

2、控制台项目使用NuGet引用需要的类库：

　　OWIN

　　Microsoft.Owin.Hosting

　　Microsoft.Owin.Host.HttpListener

　　Microsoct.AspNet.WebApi.Owin

　　这里需要手动从WebApi项目里面找到System.Web.Web,System.Net.Http等Web类库进行引用。

　　OWIN.WebApi.Srv层的引用情况（我这里有跨域配置，不需要的请忽略）

　　

　　在OWIN.WebApi层，我们需要同样引用Web的类库，我们才可以在WebApi项目控制器层继承自ApiController

 　  OWIN.WebApi层的引用情况（我这里有跨域配置，不需要的请忽略）

　　

 3、因为WebApi层要分开类库项目写，所以这里比一般的OWIN要多一些配置，在我项目的OWIN.WebApi层的config目录下，我新建了一个Global.cs类，里面的代码是对控制器的解析，代码展示如下：

  1 using System.Web.Http;  2 using System.Web.Http.Dispatcher;  3 using System;  4 using System.Collections.Concurrent;  5 using System.Collections.Generic;  6 using System.Linq;  7 using System.Net;  8 using System.Net.Http;  9 using System.Web.Http.Controllers; 10  11 namespace OWIN.WebApi.config 12 { 13     public class WebApiApplication : System.Web.HttpApplication 14     { 15         protected void Application_Start() 16         { 17             //ignore the xml return it`s setting let json return only  18             GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore; 19             GlobalConfiguration.Configuration.Formatters.Remove(GlobalConfiguration.Configuration.Formatters.XmlFormatter); 20  21             GlobalConfiguration.Configuration.Services.Replace(typeof(IHttpControllerSelector), 22             new WebApiControllerSelector(GlobalConfiguration.Configuration)); 23         } 24     } 25     /// <summary> 26     /// the WebApiControllerSelector 27     /// author:qixiao 28     /// time:2017-1-31 19:24:32 29     /// </summary> 30     public class WebApiControllerSelector : DefaultHttpControllerSelector 31     { 32         private const string NamespaceRouteVariableName = "Namespace"; 33         private readonly HttpConfiguration _configuration; 34         private readonly Lazy<ConcurrentDictionary<string, Type>> _apiControllerCache; 35  36         public WebApiControllerSelector(HttpConfiguration configuration) 37             : base(configuration) 38         { 39             _configuration = configuration; 40             _apiControllerCache = new Lazy<ConcurrentDictionary<string, Type>>( 41                 new Func<ConcurrentDictionary<string, Type>>(InitializeApiControllerCache)); 42         } 43  44         private ConcurrentDictionary<string, Type> InitializeApiControllerCache() 45         { 46             IAssembliesResolver assembliesResolver = this._configuration.Services.GetAssembliesResolver(); 47             var types = this._configuration.Services.GetHttpControllerTypeResolver() 48                 .GetControllerTypes(assembliesResolver).ToDictionary(t => t.FullName, t => t); 49  50             return new ConcurrentDictionary<string, Type>(types); 51         } 52  53         public IEnumerable<string> GetControllerFullName(HttpRequestMessage request, string controllerName) 54         { 55             object namespaceName; 56             var data = request.GetRouteData(); 57             IEnumerable<string> keys = _apiControllerCache.Value.ToDictionary<KeyValuePair<string, Type>, string, Type>(t => t.Key, 58                     t => t.Value, StringComparer.CurrentCultureIgnoreCase).Keys.ToList(); 59  60             if (!data.Values.TryGetValue(NamespaceRouteVariableName, out namespaceName)) 61             { 62                 return from k in keys 63                        where k.EndsWith(string.Format(".{0}{1}", controllerName, 64                        DefaultHttpControllerSelector.ControllerSuffix), StringComparison.CurrentCultureIgnoreCase) 65                        select k; 66             } 67  68             string[] namespaces = (string[])namespaceName; 69             return from n in namespaces 70                    join k in keys on string.Format("{0}.{1}{2}", n, controllerName, 71                    DefaultHttpControllerSelector.ControllerSuffix).ToLower() equals k.ToLower() 72                    select k; 73         } 74  75         public override HttpControllerDescriptor SelectController(HttpRequestMessage request) 76         { 77             Type type; 78             if (request == null) 79             { 80                 throw new ArgumentNullException("request"); 81             } 82             string controllerName = this.GetControllerName(request); 83             if (string.IsNullOrEmpty(controllerName)) 84             { 85                 throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound, 86                     string.Format("No route providing a controller name was found to match request URI '{0}'", new object[] { request.RequestUri }))); 87             } 88             IEnumerable<string> fullNames = GetControllerFullName(request, controllerName); 89             if (fullNames.Count() == 0) 90             { 91                 throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound, 92                         string.Format("No route providing a controller name was found to match request URI '{0}'", new object[] { request.RequestUri }))); 93             } 94  95             if (this._apiControllerCache.Value.TryGetValue(fullNames.First(), out type)) 96             { 97                 return new HttpControllerDescriptor(_configuration, controllerName, type); 98             } 99             throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound,100                 string.Format("No route providing a controller name was found to match request URI '{0}'", new object[] { request.RequestUri })));101         }102     }103 }

4、在OWIN.WebApi.Srv层里面新建AppStart.cs类，并且写如下代码：

 1 using Microsoft.Owin.Hosting; 2 using System; 3 using Owin; 4 using System.Web.Http; 5 using System.Web.Http.Dispatcher; 6 using QX_Frame.App.WebApi.Extends; 7 using System.Web.Http.Cors; 8  9 namespace OWIN.WebApi.Srv10 {11     class AppStart12     {13         static void Main(string[] args)14         {15             //string baseAddress = "http://localhost:3999/";    //localhost visit16             string baseAddress = "http://+:3999/";              //all internet environment visit  17             try18             {19                 WebApp.Start<StartUp>(url: baseAddress);20                 Console.WriteLine("BaseIpAddress is " + baseAddress);21                 Console.WriteLine("\nApplication Started !");22             }23             catch (Exception ex)24             {25                 Console.WriteLine(ex.ToString());26             }27 28             for (;;)29             {30                 Console.ReadLine();31             }32         }33     }34     //the start up configuration35     class StartUp36     {37         public void Configuration(IAppBuilder appBuilder)38         {39             HttpConfiguration config = new HttpConfiguration();40 41             // Web API configuration and services42             //跨域配置 //need reference from nuget43             config.EnableCors(new EnableCorsAttribute("*", "*", "*"));44             //enabing attribute routing45             config.MapHttpAttributeRoutes();46             // Web API Convention-based routing.47             config.Routes.MapHttpRoute(48                 name: "DefaultApi",49                 routeTemplate: "api/{controller}/{id}",50                 defaults: new { id = RouteParameter.Optional },51                 namespaces: new string[] { "OWIN.WebApi" }52             );53             config.Services.Replace(typeof(IHttpControllerSelector), new OWIN.WebApi.config.WebApiControllerSelector(config));54 55             //if config the global filter input there need not write the attributes56             //config.Filters.Add(new App.Web.Filters.ExceptionAttribute_DG());57 58             //new ClassRegisters(); //register ioc menbers59 60             appBuilder.UseWebApi(config);61         }62     }63 }

里面对地址进行了配置，当然可以根据需求自行配置，显示信息也进行了适当的展示，需要说明的一点是，我这里进行了跨域的配置，没有配置或者是不需要的请注释掉并忽略！

这里需要注意的是第53行，这里引用的是刚才的OWIN.WebApi层的Global.cs里面的类，请对照上述两段代码进行查找。

这行是关键，有了这行，程序才可以扫描到WebApi层的Controller。好了，我们进行Controller的书写。

5、在OWIN.WebApi层进行控制器类的编写，这里随意，我只在这里列出我的例子。

 1 using QX_Frame.App.WebApi; 2 using QX_Frame.Helper_DG; 3 using System.Web.Http; 4  5 namespace OWIN.WebApi 6 { 7     /* 8      * author:qixiao 9      * time:2017-2-27 10:32:5710      **/11     public class Test1Controller:ApiController12     {13         //access http://localhost:3999/api/Test1  get method14         public IHttpActionResult GetTest()15         {16             //throw new Exception_DG("login id , pwd", "argumets can not be null", 11111, 2222);17             return Json(new { IsSuccess = true, Msg = "this is get method" });18         }19         //access http://localhost:3999/api/Test1  post method20         public IHttpActionResult PostTest(dynamic queryData)21         {22             return Json(new { IsSuccess = true, Msg = "this is post method",Data=queryData });23         }24         //access http://localhost:3999/api/Test1  put method25         public IHttpActionResult PutTest()26         {27             return Json(new { IsSuccess = true, Msg = "this is put method" });28         }29         //access http://localhost:3999/api/Test1  delete method30         public IHttpActionResult DeleteTest()31         {32             return Json(new { IsSuccess = true, Msg = "this is delete method" });33         }34     }35 }

这里我是用的是RESTFull风格的WebApi控制器接口。

 然后我们可以进行试运行：

服务启动成功！

测试通过，我们可以尽情地探索后续开发步骤！