原文:

默认实现中不支持同名Controller，否则在访问时会报HttpError，在网上找到了各种路由自实现，如

在上述地址的帮助下，根据需求，重新编写了AreaHttpControllerSelector，路由原理与上述地址大同小异，均是通过路由匹配拼接FullName，然后匹配最接近的ApiController，而所谓的最接近，就是指如果根据拼接的Name获取到了多个匹配项，则获取命名空间节点数最少的那个ApiController，以保证在多次注册路由规则时，能够按照从繁到简的方式匹配出相应的Controller（需要注意的是AreaHttpControllerSelector是以controller作为结束分割点的），举例如下

假定注册了以下路由匹配规则（controller、action均为WebAPI的路由占用字符）

config.Routes.MapHttpRoute(                name: "DefaultAreaApi",                routeTemplate: "api/{area}/{controller}/{action}/{id}",                defaults: new { id = RouteParameter.Optional }            );            config.Routes.MapHttpRoute(                name: "DefaultApi",                routeTemplate: "api/{controller}/{action}/{id}",                defaults: new { id = RouteParameter.Optional }            );

在Controller目录下存在多层同名且不同层级的Controller，如：

Controller/Area/SameController，对应的命名空间为Controller.Area.SameController

Controller/SameController，对应的命名空间为Controller.SameController

通过api/Area/Same/Get将匹配到Controller/Area/SameController

通过api/Same/Get将匹配到Controller/SameController

相比于参考网址，重新编写的AreaHttpControllerSelector可以支持无限层级的区域，只要命名空间支持，比如

"api/{area1}/{area1}/{area2}/{area3}/{controller}/{action}/{id}"

以下是具体的AreaHttpControllerSelector代码

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Web;using System.Web.Http.Dispatcher;using System.Net.Http;using System.Web.Http;using System.Web.Http.Controllers;using System.Net;namespace WebAPI{    /// 
    /// Represents a area System.Web.Http.Dispatcher.IHttpControllerSelector instance    /// 
    public class AreaHttpControllerSelector : DefaultHttpControllerSelector    {        private readonly HttpConfiguration _configuration;        /// 
        /// Lazy 当前程序集中包含的所有IHttpController反射集合，TKey为小写的Controller        /// 
        private readonly Lazy
    
     
      > _apiControllerTypes;        private ILookup
      
        ApiControllerTypes        {            get            {                return this._apiControllerTypes.Value;            }        }        /// 
       
        /// Initializes a new instance of the AreaHttpControllerSelector class        /// 
        /// 
               public AreaHttpControllerSelector(HttpConfiguration configuration)            : base(configuration)        {            this._configuration = configuration;            this._apiControllerTypes = new Lazy
       
        
         >(this.GetApiControllerTypes);        }        /// 
         
 /// 获取当前程序集中 IHttpController反射集合 /// 
        /// 
                 private ILookup
         
           GetApiControllerTypes() { IAssembliesResolver assembliesResolver = this._configuration.Services.GetAssembliesResolver(); return this._configuration.Services.GetHttpControllerTypeResolver() .GetControllerTypes(assembliesResolver) .ToLookup(t => t.Name.ToLower().Substring(0, t.Name.Length - DefaultHttpControllerSelector.ControllerSuffix.Length), t => t); } /// 
          
 /// Selects a System.Web.Http.Controllers.HttpControllerDescriptor for the given System.Net.Http.HttpRequestMessage. /// 
 /// 
           /// 
           public override HttpControllerDescriptor SelectController(HttpRequestMessage request) { HttpControllerDescriptor des = null; string controllerName = this.GetControllerName(request); if (!string.IsNullOrWhiteSpace(controllerName)) { var groups = this.ApiControllerTypes[controllerName.ToLower()]; if (groups != null && groups.Any()) { string endString; var routeDic = request.GetRouteData().Values;//存在controllerName的话必定能取到IHttpRouteData if (routeDic.Count > 1) { StringBuilder tmp = new StringBuilder(); foreach (var key in routeDic.Keys) { tmp.Append('.'); tmp.Append(routeDic[key]); if (key.Equals(DefaultHttpControllerSelector.ControllerSuffix, StringComparison.CurrentCultureIgnoreCase)) {//如果是control，则代表命名空间结束 break; } } tmp.Append(DefaultHttpControllerSelector.ControllerSuffix); endString = tmp.ToString(); } else { endString = string.Format(".{0}{1}", controllerName, DefaultHttpControllerSelector.ControllerSuffix); } //取NameSpace节点数最少的Type var type = groups.Where(t => t.FullName.EndsWith(endString, StringComparison.CurrentCultureIgnoreCase)) .OrderBy(t => t.FullName.Count(s => s == '.')).FirstOrDefault();//默认返回命名空间节点数最少的第一项 if (type != null) { des = new HttpControllerDescriptor(this._configuration, controllerName, type); } } } if (des == null) { throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound, string.Format("No route providing a controller name was found to match request URI '{0}'", request.RequestUri))); } return des; } }}
         
        
       
      
     
    

而用法就是在Global文件的Application_Start方法中替换注册

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