如何在ASP.NET MVC 3项目的服务层生成URL

public class MyService
{
    private readonly HttpContextBase _httpContext;

    public MyService(HttpContextBase httpContext)
    {
        _httpContext = httpContext;
    }

    public string GenerateUrl(string actionName, string controllerName, object routeValues)
    {
        var urlHelper = new UrlHelper(_httpContext.Request.RequestContext);
        return urlHelper.Action(actionName, controllerName, routeValues);
    }
}

public class MyController : Controller
{
    private readonly MyService _myService;

    public MyController(MyService myService)
    {
        _myService = myService;
    }

    public ActionResult Index()
    {
        var url = _myService.GenerateUrl("Action", "Controller", new { id = 1 });
        return Redirect(url);
    }
}

public class MyService
{
    private readonly UrlHelper _urlHelper;

    public MyService(UrlHelper urlHelper)
    {
        _urlHelper = urlHelper;
    }

    public string GenerateUrl(string actionName, string controllerName, object routeValues)
    {
        return _urlHelper.Action(actionName, controllerName, routeValues);
    }
}

public class MyController : Controller
{
    private readonly MyService _myService;

    public MyController(MyService myService)
    {
        _myService = myService;
    }

    public ActionResult Index()
    {
        var url = _myService.GenerateUrl("Action", "Controller", new { id = 1 });
        return Redirect(url);
    }
}