参考资料：https://sites.google.com/site/netcorenote/asp-net-core/get-scheme-url-host
Example there's an given url: http://localhost:4800/account/login
获取整个url地址：
在页面(cstml)中
Microsoft.AspNetCore.Http.Extensions.UriHelper.GetDisplayUrl(Context.Request);
在 Controller 中
Microsoft.AspNetCore.Http.Extensions.UriHelper.GetDisplayUrl(Request);
获取请求的方式（scheme：http/https）:http
In asp.net 4.6 -> Request.Url.Scheme
in .net core -> Context.Request.Scheme (cshtml) , in Controller -> Request.Scheme
获取域名（不带端口号）[Get the host]:
In asp.net 4.6 -> Request.Url.Host
in .net core -> Context.Request.Host.Host (cshtml) , in Controller -> Request.Host.Host
获取域名（带端口号）[Get the host]: localhost:4800
In asp.net 4.6 ->
in .net core -> Context.Request.Host.Value (cshtml) , in Controller -> Request.Host.Value
获取路径（Get the path）: /account/login
In asp.net 4.6:
In .net core: @Context.Request.Path (cshtml)
获取端口号（Get port）: 4800 (if a url contains port)
In asp.net 4.6: Request.Url.Port
In .net core: @Context.Request.Host.Port (cshtml) , in Controller -> Request.Host.Port
