Flutter “连接被拒绝” (errno=111) 尝试发送 http 获取请求以从物理设备到 pc

Question

I built a flutter app which communicates with a web server that I wrote with flask. Everything works as intended without any errors if I use a virtual device. As soon as I try it in release mode on a physical device I get problems when it comes to the communication with the server

The only thing that I changed when using a physical device is the ip. I use 10.0.2.2 on the virtual device and my computers ip4 adress - that I get with ipconfig in windows 10 - on the physical device

• Both devices are in the same network connected to the same router
• Internet Permission is enabled in the AndroidManifest for all modes (Debug, Main, Profile)
• I even disabled the firewall

The line that causes the issue is

 await http.get(url).timeout(Duration(seconds: 15), onTimeout: () {
        // Handle timeout
        // This entire thing is in a try-catch block in an async function
      });

In debug mode on the physical device when the HTTP get request is sent VSCode immediately says

Exception has occurred.
SocketException (SocketException: OS Error: Connection refused, errno = 111, address = 192.168.178.20, port = 43378)

First Question: Why Port 43378? Is that the port the HTTP request is sent to? Because when I run the flask app it says:

Running on http://127.0.0.1:5000/

Could that be the issue? I would have expected the exception to say the port is 5000 as declared in the URL. Or do I have to change something with how I set up the flask app? Currently it is the development server because I am still testing before I pay money and deploy

However I hope I didnt forget any important information. Any advice on what could be wrong or how to debug here is highly aprecciated

Answer 1

Pass an Uri object to http.get func. Uri classes let you specify the port as Documentation https://api.dart.dev/stable/2.12.0/dart-core/Uri-class.html