下面的代码片段在MVC4中很好地为我工作，并且不需要可用的HttpContext:

System.Web.HttpRuntime.AppDomainAppVirtualPath

也许这是对这里发布的答案的扩展或修改，但我简单地使用了下面这行，它是有效的:

Request.Url.GetLeftPart(UriPartial.Authority) + Url.Content("~")

当我的路径是:http://host/iis_foldername/controller/action 然后我收到:http://host/iis_foldername/

简单地在一行中获取BaseUrl

string baseUrl = new Uri(Request.Url, Url.Content("~")).AbsoluteUri;

//output example: https://stackoverflow.com

这是我的解决方案(使用。net core 3.1，在api控制器中):

string baseUrl = $"{Request.Scheme}://{Request.Headers.Where(h => h.Key == "Host").First().Value}";

下面的方法对我很有效

var request = HttpContext.Request;
                        var appUrl = System.Web.HttpRuntime.AppDomainAppVirtualPath;

                        if (appUrl != "/")
                            appUrl = "/" + appUrl + "/";

                        var newUrl = string.Format("{0}://{1}{2}{3}/{4}", request.Url.Scheme, request.UrlReferrer.Host, appUrl, "Controller", "Action");

对于MVC 4:

String.Format("{0}://{1}{2}", Url.Request.RequestUri.Scheme, Url.Request.RequestUri.Authority, ControllerContext.Configuration.VirtualPathRoot);