[assembly: PreApplicationStartMethod(typeof(SwaggerConfig), "Register")]

namespace WebApplication1
{
    public class SwaggerConfig
    {
        public static void Register()
        {
            var thisAssembly = typeof(SwaggerConfig).Assembly;

            GlobalConfiguration.Configuration
                .EnableSwagger(c =>
                {
                    c.SingleApiVersion("v1", "WebApp");


                })
                .EnableSwaggerUi(c =>
                {
                    GetXmlCommentsPath();
                });
        }
        private static string GetXmlCommentsPath()
        {
            return $@"{System.AppDomain.CurrentDomain.BaseDirectory}\bin\WebApi.XML";
        }
}

namespace WebApi
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // Web API configuration and services

            // Web API routes
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi1",
                routeTemplate: "api/{controller}/{action}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

            config.Routes.MapHttpRoute(
               name: "DefaultApi2",
               routeTemplate: "api/{controller}/{action}/{id}",
               defaults: new { action="get",id = RouteParameter.Optional }
           );
        }
    }
}

public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            GlobalConfiguration.Configure(WebApiConfig.Register);   //这是要加的
        }
    }