获取客户端上流服务器的端口号[在heroku上运行]

我正在尝试将我的dart应用程序部署在heroku上，但是即使当我的流服务器在dyno中运行时，我也不知道如何获取客户端代码上的端口号以进行连接通过websocket服务器。由于我无法使用 Platform.environment ['PORT'] ，因此我不知道如何获取端口。

I am trying to deploy my dart application on heroku but even when i have got my stream server running in the dyno, i don't have any idea as to how can i get the port number on client side code to connect to the server via websocket. Since i cannot use Platform.environment['PORT'], i don't know how to get the port.

我的客户端网络套接字地址是这样的：

My client side websocket address is this:

var port = '<The port number i need>';
var url = 'ws://0.0.0.0:$port/ws';

为成功部署到heroku付出了很多努力。请告诉我，有一种方法可以使这项工作。

It has taken a lot of effort to deploy successfully to heroku. Please tell me that there is a way to make this work.