MVC5 ResolveUrl in static code

ASP.NET MVC5常用Url.Content(virtualPath)來取得實際的URL，若是在static程式區塊裏，要取得頁面實際路徑的簡易方式為System.Web.VirtualPathUtility.ToAbsolute(virtualPath)，然而它無法處理http://路徑(會丟出例外)，因此要額外處理它：

public static string ResolveUrl(string virtualPath)
{
	if (virtualPath == null)
		return null;

	// VirtualPathUtility can't handle the http://xxx path.
	if (virtualPath.IndexOf("://") != -1)
		return virtualPath;

	// Resolve the ~/ tilde.
	if (virtualPath.StartsWith("~"))
		return System.Web.VirtualPathUtility.ToAbsolute(virtualPath);

	return virtualPath;
}