Network messaging from Java PC application to Android Wear 2.0 app

Question

I need to send messages from a Java program on my PC to an Android Wear 2.0 app. The watch is directly (no intermediate phone) connected to a mobile hotspot (default hotspot setup by Windows 10 settings) on the PC that I want to send the messages from. Wifi adb debugging happens flawless over this local network.

The goal is a one-to-one communication, so I worked with simple Java Networking sockets. The laptop acts as server, the watch as client. On the wear app, this happens in a seperate AsyncTask:

@Override
protected Void doInBackground(Void... voids) {
    try(Socket audioSocket = new Socket("localhost",4445);
        PrintWriter out = new PrintWriter(audioSocket.getOutputStream(),true);
        BufferedReader in = new BufferedReader(new InputStreamReader(audioSocket.getInputStream()));){
        while(true){
            String msg = in.readLine();
            // do something with msg
        }
    }
    catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}

On the Java PC application, the server also runs in a seperate thread:

@Override
public void run() {
    ServerSocket serverSocket = new ServerSocket(4445);
    while (true) {
        try(Socket clientSocket = serverSocket.accept()) {
            try(PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
                BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));) {
                while (true) {
                    // send messages
                }
            }
        } catch (IOException ex) {
            Logger.getLogger(AudioServer.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

In the manifest of the wear app, I ask for the following permission:

<uses-permission android:name="android.permission.INTERNET" />

The Java PC application runs fine. However, when I run the wear app, I get the following error:

System.err: java.net.ConnectException: Connection refused

What is the reason for this error? Or is there a better way to have a one-to-one communication between wearable and PC application (security isn't important in this case)?

Answer 1

我自己找到了解决方案：我将localhost更改为Windows热点的默认IP地址192.168.137.1 。