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");

所以这里列出的这些方法都不适合我，但通过使用其中的一些答案，我找到了一些有用的方法:

public string GetBaseUrl()
{
    var request = HttpContext.Current.Request;
    var appUrl = HttpRuntime.AppDomainAppVirtualPath;

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

    var baseUrl = string.Format("{0}://{1}{2}", request.Url.Scheme, request.Url.Authority, appUrl);

    return baseUrl;
}

更新ASP。NET Core / MVC 6:

ASP。NET Core使这个过程更加痛苦，特别是当您深入代码时。你有两个选项来获取HttpContext

1)从控制器传入:

var model = new MyClass(HttpContext);

然后在模型中:

private HttpContext currentContext;

public MyClass(HttpContext currentContext)
{
    this.currentContext = currentContext;
}

2)也许更干净的方法是将它注入到你的类中，首先在你的Startup中注册类型:

public void ConfigureServices(IServiceCollection services)
{
    // Add framework services.
    services.AddMvc();

    services.AddTransient<MyClass, MyClass>();
    services.TryAddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}

然后像这样为你注射:

private HttpContext currentContext;

public MyClass(IHttpContextAccessor httpContextAccessor)
{
    currentContext = httpContextAccessor.HttpContext;
}

在任何情况下，这是更新的。net Core GetBaseUrl():

public string GetBaseUrl()
{
    var request = currentContext.Request;

    var host = request.Host.ToUriComponent();

    var pathBase = request.PathBase.ToUriComponent();

    return $"{request.Scheme}://{host}{pathBase}";
}

在代码:

Url.Content("~/");

MVC3 Razor语法:

@Url.Content("~/")

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");

将此函数添加到项目的静态类中，如实用程序类:

utility.cs内容:

public static class Utility
{
    public static string GetBaseUrl()
    {
        var request = HttpContext.Current.Request;
        var urlHelper = new UrlHelper(request.RequestContext);
        var baseUrl = $"{request.Url.Scheme}://{request.Url.Authority}{urlHelper.Content("~")}";
        return baseUrl;
    }
}

在任何地方使用这段代码并享受它:

var baseUrl = Utility.GetBaseUrl();

对于MVC 4:

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