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;
    }
}

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);
}

在定义了一个新的Route处理程序(它将查看URL中传递的主机)之后，您可以使用一个基本控制器的思想，它知道正在访问它的站点。它是这样的:

public abstract class SiteController : Controller {
    ISiteProvider _siteProvider;

    public SiteController() {
        _siteProvider = new SiteProvider();
    }

    public SiteController(ISiteProvider siteProvider) {
        _siteProvider = siteProvider;
    }

    protected override void Initialize(RequestContext requestContext) {
        string[] host = requestContext.HttpContext.Request.Headers["Host"].Split(':');

        _siteProvider.Initialise(host[0]);

        base.Initialize(requestContext);
    }

    protected override void OnActionExecuting(ActionExecutingContext filterContext) {
        ViewData["Site"] = Site;

        base.OnActionExecuting(filterContext);
    }

    public Site Site {
        get {
            return _siteProvider.GetCurrentSite();
        }
    }

}

ISiteProvider是一个简单的接口:

public interface ISiteProvider {
    void Initialise(string host);
    Site GetCurrentSite();
}

我建议你去卢克·桑普森的博客

是的，但是你必须创建你自己的路由处理器。

通常情况下，路由不知道域，因为应用程序可以部署到任何域，路由不会关心这种或那种方式。但在你的情况下，你想要基于域的控制器和动作，所以你必须创建一个自定义路由，它可以感知域。

几个月前，我开发了一个属性，将方法或控制器限制在特定的域。

它很容易使用:

[IsDomain("localhost","example.com","www.example.com","*.t1.example.com")]
[HttpGet("RestrictedByHost")]
public IActionResult Test(){}

也可以直接应用到控制器上。

public class IsDomainAttribute : Attribute, Microsoft.AspNetCore.Mvc.Filters.IAuthorizationFilter
{

    public IsDomainAttribute(params string[]  domains)
    {
        Domains = domains;
    }

    public string[] Domains { get; }

    public void OnAuthorization(AuthorizationFilterContext context)
    {
        var host = context.HttpContext.Request.Host.Host;
        if (Domains.Contains(host))
            return;
        if (Domains.Any(d => d.EndsWith("*"))
                && Domains.Any(d => host.StartsWith(d.Substring(0, d.Length - 1))))
            return;
        if (Domains.Any(d => d.StartsWith("*"))
                && Domains.Any(d => host.EndsWith(d.Substring(1))))
            return;

        context.Result = new Microsoft.AspNetCore.Mvc.NotFoundResult();//.ChallengeResult
    }
}

限制: 你可能不能在不同的过滤器的不同方法上有两个相同的路由 我的意思是下面可能会抛出重复路由的异常:

[IsDomain("test1.example.com")]
[HttpGet("/Test")]
public IActionResult Test1(){}

[IsDomain("test2.example.com")]
[HttpGet("/Test")]
public IActionResult Test2(){}

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;
    }
}