您可以在视图中使用以下脚本:

<script type="text/javascript">
    var BASE_URL = '<%= ResolveUrl("~/") %>';
</script>

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

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}";
}

对于MVC 4:

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

网页本身:

<input type="hidden" id="basePath" value="@string.Format("{0}://{1}{2}",
  HttpContext.Current.Request.Url.Scheme,
  HttpContext.Current.Request.Url.Authority,
  Url.Content("~"))" />

在javascript中:

function getReportFormGeneratorPath() {
  var formPath = $('#reportForm').attr('action');
  var newPath = $("#basePath").val() + formPath;
  return newPath;
}

这适用于我的MVC项目，希望它有帮助

ASP。NET MVC 4有点不同:

string url = HttpContext.Request.Url.AbsoluteUri;