Web Api Route 注册要放在 Mvc Route 注册前

今天想研究一下Web Api，写了一个测试Api，打开网站后浏览一下，可是却提示找不到方法，刚开始以为哪里配置错了，可找了半天也没见。

因为我是在一个现有Mvc站点做的Demo，所以打算新建一个Mvc网站，再试一下，新站点是正常的，对比一下Global文件，发现WebApiConfig和RouteConfig顺序不一样。

如果把新站点的RouteConfig也放在WebApiConfig之前，同样提示找不到方法。看来这两个配置有关联呀。

      WebApiConfig.Register(GlobalConfiguration.Configuration);
      RouteConfig.RegisterRoutes(RouteTable.Routes);

　　看了一下GlobalConfiguration类就明白了

    public static class GlobalConfiguration
    {
        private static Lazy<HttpConfiguration> _configuration = new Lazy<HttpConfiguration>(delegate {
            HttpConfiguration configuration = new HttpConfiguration(new HostedHttpRouteCollection(RouteTable.Routes));
            configuration.Services.Replace(typeof(IAssembliesResolver), new WebHostAssembliesResolver());
            configuration.Services.Replace(typeof(IHttpControllerTypeResolver), new WebHostHttpControllerTypeResolver());
            configuration.Services.Replace(typeof(IHostBufferPolicySelector), new WebHostBufferPolicySelector());
            return configuration;
        });
        public static HttpConfiguration Configuration
        {
            get
            {
                return _configuration.Value;
            }
        }
        
       //...
    }

　　

 public class RouteConfig
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                name: "Default",
                url: "t/{controller}/{action}/{id}",
                defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
            );
        }
    }

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

　　合并后的类似路由：

            routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
            routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
            );

如果顺序反了，DefaultApi的路由就永远匹配不到了，会一直找MVC的路由"{api}/{action}/{id}"。