设置WebApi里面命名空间参数

在这种情况下：

如果没有特别处理，会报：

所以要像MVC中的控制器一下配置一个命名空间参数，webapi里面没有自带这个功能

代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http;
using System.Web.Http.Dispatcher;
using AutoData.Utility;

namespace AutoData
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            config.MapHttpAttributeRoutes();
            //config.HostNameComparisonMode = HostNameComparisonMode.Exact;
            
            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

            config.Routes.MapHttpRoute(
                name: "Admin Area Default",
                routeTemplate: "api/admin/{controller}/{action}/{id}",
                defaults: new { id = RouteParameter.Optional, namespaceName = "AutoData.Areas.Admin.Controllers"  }
            );

            config.Routes.MapHttpRoute(
               name: "IndustryInsight Area Default",
               routeTemplate: "Api/IndustryInsight/{controller}/{action}/{id}",
               defaults: new { id = RouteParameter.Optional }
           );

            config.Routes.MapHttpRoute(
             name: "ComputeFormula Area Default",
             routeTemplate: "Api/ComputeFormula/{controller}/{action}/{id}",
             defaults: new { id = RouteParameter.Optional , namespaceName = "AutoData.Areas.ComputeFormula.Controllers"}
         );
            config.Services.Replace(typeof(IHttpControllerSelector), new NamespaceHttpControllerSelector(config));
        }
    }
}

最后一句设置，也可以配置在全局类里面：

 GlobalConfiguration.Configuration.Services.Replace(typeof(IHttpControllerSelector), new NamespaceHttpControllerSelector(GlobalConfiguration.Configuration));

功能是一样的

NamespaceHttpConrollerSelector类

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Text.RegularExpressions;
using System.Web;
using System.Web.Http;
using System.Web.Http.Controllers;
using System.Web.Http.Dispatcher;
using System.Web.Http.Routing;

namespace AutoData.Utility
{
    public class NamespaceHttpControllerSelector : IHttpControllerSelector
    {
        private const string NamespaceKey = "namespaceName";
        private const string ControllerKey = "controller";

        private readonly HttpConfiguration _configuration;
        private readonly Lazy<Dictionary<string, HttpControllerDescriptor>> _controllers;
        private readonly HashSet<string> _duplicates;

        public NamespaceHttpControllerSelector(HttpConfiguration config)
        {
            _configuration = config;
            _duplicates = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            _controllers = new Lazy<Dictionary<string, HttpControllerDescriptor>>(InitializeControllerDictionary);
        }

        private Dictionary<string, HttpControllerDescriptor> InitializeControllerDictionary()
        {
            var dictionary = new Dictionary<string, HttpControllerDescriptor>(StringComparer.OrdinalIgnoreCase);

            // Create a lookup table where key is "namespace.controller". The value of "namespace" is the last
            // segment of the full namespace. For example:
            // MyApplication.Controllers.V1.ProductsController => "V1.Products"
            IAssembliesResolver assembliesResolver = _configuration.Services.GetAssembliesResolver();
            IHttpControllerTypeResolver controllersResolver = _configuration.Services.GetHttpControllerTypeResolver();

            ICollection<Type> controllerTypes = controllersResolver.GetControllerTypes(assembliesResolver);

            foreach (Type t in controllerTypes)
            {
                var segments = t.Namespace.Split(Type.Delimiter);

                // For the dictionary key, strip "Controller" from the end of the type name.
                // This matches the behavior of DefaultHttpControllerSelector.
                var controllerName = t.Name.Remove(t.Name.Length - DefaultHttpControllerSelector.ControllerSuffix.Length);

                //var key = String.Format(CultureInfo.InvariantCulture, "{0}.{1}", segments[segments.Length - 1], controllerName); //旧版本
                var key = String.Format(CultureInfo.InvariantCulture, "{0}.{1}", t.Namespace.ToString(), controllerName);    //新版本

                // Check for duplicate keys.
                if (dictionary.Keys.Contains(key))
                {
                    _duplicates.Add(key);
                }
                else
                {
                    dictionary[key] = new HttpControllerDescriptor(_configuration, t.Name, t);
                }
            }

            // Remove any duplicates from the dictionary, because these create ambiguous matches. 
            // For example, "Foo.V1.ProductsController" and "Bar.V1.ProductsController" both map to "v1.products".
            foreach (string s in _duplicates)
            {
                dictionary.Remove(s);
            }
            return dictionary;
        }

        // Get a value from the route data, if present.
        private static T GetRouteVariable<T>(IHttpRouteData routeData, string name)
        {
            object result = null;
            if (routeData.Values.TryGetValue(name, out result))
            {
                return (T)result;
            }
            return default(T);
        }

        public HttpControllerDescriptor SelectController(HttpRequestMessage request)
        {
            IHttpRouteData routeData = request.GetRouteData();
            if (routeData == null)
            {
                throw new HttpResponseException(HttpStatusCode.NotFound);
            }

            // Get the namespace and controller variables from the route data.
            string namespaceName = GetRouteVariable<string>(routeData, NamespaceKey);
            if (namespaceName == null)
            {
                throw new HttpResponseException(HttpStatusCode.NotFound);
            }

            string controllerName = GetRouteVariable<string>(routeData, ControllerKey);
            if (controllerName == null)
            {
                throw new HttpResponseException(HttpStatusCode.NotFound);
            }

            // Find a matching controller.
            string key = String.Format(CultureInfo.InvariantCulture, "{0}.{1}", namespaceName, controllerName);

            HttpControllerDescriptor controllerDescriptor;
            if (_controllers.Value.TryGetValue(key, out controllerDescriptor))
            {
                return controllerDescriptor;
            }
            else if (_duplicates.Contains(key))
            {
                throw new HttpResponseException(
                    request.CreateErrorResponse(HttpStatusCode.InternalServerError,
                    "Multiple controllers were found that match this request."));
            }
            else
            {
                throw new HttpResponseException(HttpStatusCode.NotFound);
            }
        }

        public IDictionary<string, HttpControllerDescriptor> GetControllerMapping()
        {
            return _controllers.Value;
        }
    }
}

对它进行了一点点的修改，

旧版本的命名空间选.号的最后一个

我设置的取全名命名空间

这样设置以后会发现一起没有设置命名空间的路由会发生错误，所有WebApiConfig里面的路由必须设置命名空间

http://www.cnblogs.com/nikyxxx/p/3356659.html

http://aspnet.codeplex.com/SourceControl/changeset/view/dd207952fa86#Samples/WebApi/NamespaceControllerSelector/NamespaceHttpControllerSelector.cs

http://www.osdo.net/article/2015/01/13/160.html

http://blog.csdn.net/starfd/article/details/41728655