c# – 为什么我的区域特定的Web API可以从所有其他区域访问？

ASP.NET MVC 4 does not support the partitioning of Web API controllers across Areas.

您可以将WebApi控制器放在不同区域的不同Api文件夹中,但是ASP.NET MVC将会被视为处于同一个地方.

幸运的是,您可以通过覆盖ASP.NET MVC基础架构的一部分来克服此限制.有关限制和解决方案的更多信息,请阅读我的博客文章’ASP.NET MVC 4 RC: Getting WebApi and Areas to play nicely‘.如果您只对解决方案感兴趣,请继续阅读：

步骤1.使您的路线区域知道

将以下扩展方法添加到ASP.NET MVC应用程序,并确保它们可以从您的AreaRegistration类访问：

public static class AreaRegistrationContextExtensions
{
    public static Route MapHttpRoute(this AreaRegistrationContext context,string name,string routeTemplate)
    {
        return context.MapHttpRoute(name,routeTemplate,null,null);
    }

    public static Route MapHttpRoute(this AreaRegistrationContext context,string routeTemplate,object defaults)
    {
        return context.MapHttpRoute(name,defaults,object defaults,object constraints)
    {
        var route = context.Routes.MapHttpRoute(name,constraints);
        if (route.DataTokens == null)
        {
            route.DataTokens = new RouteValueDictionary();
        }
        route.DataTokens.Add("area",context.AreaName);
        return route;
    }
}

要使用新的扩展方法,请从呼叫链中删除路由属性：

context.MapHttpRoute( /* <-- .Routes removed */
    name: "Administration_DefaultApi",defaults: new { id = RouteParameter.Optional }
);

步骤2.使Web API控制器选择器区域感知

将以下类添加到您的ASP.NET MVC应用程序,并确保它可以从Global.asax访问

namespace MvcApplication.Infrastructure.Dispatcher
{
    using System;
    using System.Collections.Concurrent;
    using System.Collections.Generic;
    using System.Globalization;
    using System.Linq;
    using System.Net.Http;
    using System.Web.Http;
    using System.Web.Http.Controllers;
    using System.Web.Http.Dispatcher;

    public class AreaHttpControllerSelector : DefaultHttpControllerSelector
    {
        private const string AreaRouteVariableName = "area";

        private readonly HttpConfiguration _configuration;
        private readonly Lazy<ConcurrentDictionary<string,Type>> _apiControllerTypes;

        public AreaHttpControllerSelector(HttpConfiguration configuration)
            : base(configuration)
        {
            _configuration = configuration;
            _apiControllerTypes = new Lazy<ConcurrentDictionary<string,Type>>(GetControllerTypes);
        }

        public override HttpControllerDescriptor SelectController(HttpRequestMessage request)
        {
            return this.GetApiController(request);
        }

        private static string GetAreaName(HttpRequestMessage request)
        {
            var data = request.GetRouteData();
            if (data.Route.DataTokens == null)
            {
                return null;
            } 
            else 
            {
                object areaName;
                return data.Route.DataTokens.TryGetValue(AreaRouteVariableName,out areaName) ? areaName.ToString() : null;
            }
        }

        private static ConcurrentDictionary<string,Type> GetControllerTypes()
        {
            var assemblies = AppDomain.CurrentDomain.GetAssemblies();

            var types = assemblies
                .SelectMany(a => a
                    .GetTypes().Where(t =>
                        !t.IsAbstract &&
                        t.Name.EndsWith(ControllerSuffix,StringComparison.OrdinalIgnoreCase) &&
                        typeof(IHttpController).IsAssignableFrom(t)))
                .ToDictionary(t => t.FullName,t => t);

            return new ConcurrentDictionary<string,Type>(types);
        }

        private HttpControllerDescriptor GetApiController(HttpRequestMessage request)
        {
            var areaName = GetAreaName(request);
            var controllerName = GetControllerName(request);
            var type = GetControllerType(areaName,controllerName);

            return new HttpControllerDescriptor(_configuration,controllerName,type);
        }

        private Type GetControllerType(string areaName,string controllerName)
        {
            var query = _apiControllerTypes.Value.AsEnumerable();

            if (string.IsNullOrEmpty(areaName))
            {
                query = query.WithoutAreaName();
            }
            else
            {
                query = query.ByAreaName(areaName);
            }

            return query
                .ByControllerName(controllerName)
                .Select(x => x.Value)
                .Single();
        }
    }

    public static class ControllerTypeSpecifications
    {
        public static IEnumerable<KeyValuePair<string,Type>> ByAreaName(this IEnumerable<KeyValuePair<string,Type>> query,string areaName)
        {
            var areaNameToFind = string.Format(CultureInfo.InvariantCulture,".{0}.",areaName);

            return query.Where(x => x.Key.IndexOf(areaNameToFind,StringComparison.OrdinalIgnoreCase) != -1);
        }

        public static IEnumerable<KeyValuePair<string,Type>> WithoutAreaName(this IEnumerable<KeyValuePair<string,Type>> query)
        {
            return query.Where(x => x.Key.IndexOf(".areas.",StringComparison.OrdinalIgnoreCase) == -1);
        }

        public static IEnumerable<KeyValuePair<string,Type>> ByControllerName(this IEnumerable<KeyValuePair<string,string controllerName)
        {
            var controllerNameToFind = string.Format(CultureInfo.InvariantCulture,".{0}{1}",AreaHttpControllerSelector.ControllerSuffix);

            return query.Where(x => x.Key.EndsWith(controllerNameToFind,StringComparison.OrdinalIgnoreCase));
        }
    }
}

通过将以下行添加到Global.asax中的Application_Start方法来覆盖DefaultHttpControllerSelector.

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

恭喜,您的Web API控制器现在将像您正常的MVC控制器一样尊重您所在区域的规则！

更新：2012年9月6日

几位开发人员已经联系了我们关于路由变量的DataTokens属性为空的遇到的情况.我的实现假定DataTokens属性始终是初始化的,如果此属性为空,则它将无法正常运行.这种行为很可能是由于ASP.NET MVC框架中最近的变化而引起的,可能实际上是框架中的一个错误.我已经更新了我的代码来处理这种情况.