你可以通过创建一个新路由并将其添加到global.asax中的RegisterRoutes中的routes集合来实现。下面是一个自定义路由的简单例子:

public class ExampleRoute : RouteBase
{

    public override RouteData GetRouteData(HttpContextBase httpContext)
    {
        var url = httpContext.Request.Headers["HOST"];
        var index = url.IndexOf(".");

        if (index < 0)
            return null;

        var subDomain = url.Substring(0, index);

        if (subDomain == "user1")
        {
            var routeData = new RouteData(this, new MvcRouteHandler());
            routeData.Values.Add("controller", "User1"); //Goes to the User1Controller class
            routeData.Values.Add("action", "Index"); //Goes to the Index action on the User1Controller

            return routeData;
        }

        if (subDomain == "user2")
        {
            var routeData = new RouteData(this, new MvcRouteHandler());
            routeData.Values.Add("controller", "User2"); //Goes to the User2Controller class
            routeData.Values.Add("action", "Index"); //Goes to the Index action on the User2Controller

            return routeData;
        }

        return null;
    }

    public override VirtualPathData GetVirtualPath(RequestContext requestContext, RouteValueDictionary values)
    {
        //Implement your formating Url formating here
        return null;
    }
}

这不是我的工作，但我必须把它加到这个答案上。

这里有一个解决这个问题的好办法。martin Balliauw编写了创建DomainRoute类的代码，该类可以与正常的路由使用非常相似。

http://blog.maartenballiauw.be/post/2009/05/20/ASPNET-MVC-Domain-Routing.aspx

示例使用如下所示……

routes.Add("DomainRoute", new DomainRoute( 
    "{customer}.example.com", // Domain with parameters 
    "{action}/{id}",    // URL with parameters 
    new { controller = "Home", action = "Index", id = "" }  // Parameter defaults 
))

;

你可以通过创建一个新路由并将其添加到global.asax中的RegisterRoutes中的routes集合来实现。下面是一个自定义路由的简单例子:

public class ExampleRoute : RouteBase
{

    public override RouteData GetRouteData(HttpContextBase httpContext)
    {
        var url = httpContext.Request.Headers["HOST"];
        var index = url.IndexOf(".");

        if (index < 0)
            return null;

        var subDomain = url.Substring(0, index);

        if (subDomain == "user1")
        {
            var routeData = new RouteData(this, new MvcRouteHandler());
            routeData.Values.Add("controller", "User1"); //Goes to the User1Controller class
            routeData.Values.Add("action", "Index"); //Goes to the Index action on the User1Controller

            return routeData;
        }

        if (subDomain == "user2")
        {
            var routeData = new RouteData(this, new MvcRouteHandler());
            routeData.Values.Add("controller", "User2"); //Goes to the User2Controller class
            routeData.Values.Add("action", "Index"); //Goes to the Index action on the User2Controller

            return routeData;
        }

        return null;
    }

    public override VirtualPathData GetVirtualPath(RequestContext requestContext, RouteValueDictionary values)
    {
        //Implement your formating Url formating here
        return null;
    }
}

为了在使用Web API时捕获子域，重写Action Selector以注入子域查询参数。然后在控制器的动作中使用子域查询参数，如下所示:

public string Get(string id, string subdomain)

这种方法使调试更加方便，因为当使用localhost而不是实际的主机名时，可以手动指定查询参数(有关详细信息，请参阅标准MVC5路由答案)。这是动作选择器的代码:

class SubdomainActionSelector : IHttpActionSelector
{
    private readonly IHttpActionSelector defaultSelector;

    public SubdomainActionSelector(IHttpActionSelector defaultSelector)
    {
        this.defaultSelector = defaultSelector;
    }

    public ILookup<string, HttpActionDescriptor> GetActionMapping(HttpControllerDescriptor controllerDescriptor)
    {
        return defaultSelector.GetActionMapping(controllerDescriptor);
    }

    public HttpActionDescriptor SelectAction(HttpControllerContext controllerContext)
    {
        var routeValues = controllerContext.Request.GetRouteData().Values;
        if (!routeValues.ContainsKey("subdomain")) {
            string host = controllerContext.Request.Headers.Host;
            int index = host.IndexOf('.');
            if (index >= 0)
                controllerContext.Request.GetRouteData().Values.Add("subdomain", host.Substring(0, index));
        }
        return defaultSelector.SelectAction(controllerContext);
    }
}

通过将其添加到WebApiConfig来替换默认的动作选择器。注册:

config.Services.Replace(typeof(IHttpActionSelector), new SubdomainActionSelector(config.Services.GetActionSelector()));

我创建了子域路由库，您可以创建这样的路由。它目前正在为。net Core 1.1和。net Framework 4.6.1工作，但将在不久的将来进行更新。它是这样工作的: 1)在Startup.cs中映射子域路由

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    var hostnames = new[] { "localhost:54575" };

    app.UseMvc(routes =>
    {
        routes.MapSubdomainRoute(
            hostnames,
            "SubdomainRoute",
            "{username}",
            "{controller}/{action}",
            new { controller = "Home", action = "Index" });
    )};

2)控制器/ HomeController.cs

public IActionResult Index(string username)
{
    //code
}

3)该库还将允许您生成url和表单。代码:

@Html.ActionLink("User home", "Index", "Home" new { username = "user1" }, null)

将生成<a href="http://user1。localhost: 54575 / Home /指数”> < / >用户家里 生成的URL还取决于当前主机位置和模式。 你也可以为BeginForm和UrlHelper使用html帮助。如果你喜欢，你也可以使用新功能称为标签助手(FormTagHelper, AnchorTagHelper) 该库还没有任何文档，但有一些测试和示例项目，所以请随意探索。

在ASP。NET Core，主机可以通过Request.Host.Host获得。如果您希望允许通过查询参数覆盖主机，首先检查Request.Query。

要使主机查询参数传播到新的基于路由的url，将以下代码添加到app.UseMvc路由配置中:

routes.Routes.Add(new HostPropagationRouter(routes.DefaultHandler));

然后像这样定义HostPropagationRouter:

/// <summary>
/// A router that propagates the request's "host" query parameter to the response.
/// </summary>
class HostPropagationRouter : IRouter
{
    readonly IRouter router;

    public HostPropagationRouter(IRouter router)
    {
        this.router = router;
    }

    public VirtualPathData GetVirtualPath(VirtualPathContext context)
    {
        if (context.HttpContext.Request.Query.TryGetValue("host", out var host))
            context.Values["host"] = host;
        return router.GetVirtualPath(context);
    }

    public Task RouteAsync(RouteContext context) => router.RouteAsync(context);
}