WebApi自定义返回类型和命名空间实现

1.自定义ContentNegotiator

/// <summary>
    /// 返回json的ContentNegotiator
    /// </summary>
    public class JsonContentNegotiator : IContentNegotiator
    {
        private readonly JsonMediaTypeFormatter _jsonFormatter;

        public JsonContentNegotiator(JsonMediaTypeFormatter formatter)
        {
            _jsonFormatter = formatter;
        }

        public ContentNegotiationResult Negotiate(Type type, HttpRequestMessage request, IEnumerable<MediaTypeFormatter> formatters)
        {
            return new ContentNegotiationResult(_jsonFormatter, new MediaTypeHeaderValue("application/json"));
        }
    }

2.自定义HttpControllerSelector

/// <summary>
    /// 设置api支持namespace
    /// </summary>
    public class NamespaceHttpControllerSelector : DefaultHttpControllerSelector
    {
        private const string NamespaceRouteVariableName = "namespace_name";
        private readonly HttpConfiguration _configuration;
        private readonly Lazy<ConcurrentDictionary<string, Type>> _apiControllerCache;

        public NamespaceHttpControllerSelector(HttpConfiguration configuration)
            : base(configuration)
        {
            _configuration = configuration;
            _apiControllerCache = new Lazy<ConcurrentDictionary<string, Type>>(
                new Func<ConcurrentDictionary<string, Type>>(InitializeApiControllerCache));
        }

        private ConcurrentDictionary<string, Type> InitializeApiControllerCache()
        {
            IAssembliesResolver assembliesResolver = this._configuration.Services.GetAssembliesResolver();
            var types = this._configuration.Services.GetHttpControllerTypeResolver().GetControllerTypes(assembliesResolver).ToDictionary(t => t.FullName, t => t);

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

        public IEnumerable<string> GetControllerFullName(HttpRequestMessage request, string controllerName)
        {
            object namespaceName;
            var data = request.GetRouteData();
            IEnumerable<string> keys = _apiControllerCache.Value.ToDictionary<KeyValuePair<string, Type>, string, Type>(t => t.Key,
                    t => t.Value, StringComparer.CurrentCultureIgnoreCase).Keys.ToList();

            if (!data.Values.TryGetValue(NamespaceRouteVariableName, out namespaceName))
            {
                return from k in keys
                       where k.EndsWith(string.Format(".{0}{1}", controllerName,
                       DefaultHttpControllerSelector.ControllerSuffix), StringComparison.CurrentCultureIgnoreCase)
                       select k;
            }

            string[] namespaces = (string[])namespaceName;
            return from n in namespaces
                   join k in keys on string.Format("{0}.{1}{2}", n, controllerName,
                   DefaultHttpControllerSelector.ControllerSuffix).ToLower() equals k.ToLower()
                   select k;
        }

        public override HttpControllerDescriptor SelectController(HttpRequestMessage request)
        {
            Type type;
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }
            string controllerName = this.GetControllerName(request);
            if (string.IsNullOrEmpty(controllerName))
            {
                throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound,
                    string.Format("No route providing a controller name was found to match request URI '{0}'", new object[] { request.RequestUri })));
            }
            IEnumerable<string> fullNames = GetControllerFullName(request, controllerName);
            if (fullNames.Count() == 0)
            {
                throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound, string.Format("No route providing a controller name was found to match request URI '{0}'", new object[] { request.RequestUri })));
            }

            if (this._apiControllerCache.Value.TryGetValue(fullNames.First(), out type))
            {
                return new HttpControllerDescriptor(_configuration, controllerName, type);
            }
            throw new HttpResponseException(request.CreateErrorResponse(HttpStatusCode.NotFound, string.Format("No route providing a controller name was found to match request URI '{0}'", new object[] { request.RequestUri })));
        }
    }

 3.注册路由

public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            //注册返回json的ContentNegotiator，替换默认的DefaultContentNegotiator
            var jsonFormatter = new JsonMediaTypeFormatter();
            config.Services.Replace(typeof(IContentNegotiator), new JsonContentNegotiator(jsonFormatter));

            //注册支持namespace的HttpControllerSelector，替换默认DefaultHttpControllerSelector
            config.Services.Replace(typeof(IHttpControllerSelector), new NamespaceHttpControllerSelector(GlobalConfiguration.Configuration));

            config.Routes.MapHttpRoute(
                name: "PC",
                routeTemplate: "api/pc/{controller}/{action}/{id}",
                defaults: new
                {
                    id = RouteParameter.Optional,
                    namespace_name = new string[] { "HGL.Web.ApiControllers.PC" }
                }
            );

            config.Routes.MapHttpRoute(
                name: "Phone",
                routeTemplate: "api/phone/{controller}/{action}/{id}",
                defaults: new
                {
                    id = RouteParameter.Optional,
                    namespace_name = new string[] { "HGL.Web.ApiControllers.Phone" }
                }
            );

            config.Routes.MapHttpRoute(
                name: "ApiDefault",
                routeTemplate: "api/{controller}/{action}/{id}",
                defaults: new
                {
                    id = RouteParameter.Optional,
                    namespace_name = new string[] { "HGL.Web.ApiControllers" }
                }
            );
        }
    }