Android socket.io application can't connect to node.js server

Question

my application, using socket.io, cant connect to node.js server.

server node.js

var app = require('http').createServer()
var io = require('socket.io')(app);

app.listen(1000);

io.on('connection', function (client) { 

  client.name = client.remoteAddress + ':' + client.remotePort;
  console.log(client.name + ' connected!'); 

    client.on('sensorChanged', function (data) {
        console.log("HERE");
        console.log(data);
    });

});

android application:

    SocketIO socket = new SocketIO();
    try {
        socket.connect("http://localhost:1000/", this);
        txtView.setText("connected");
    } catch (MalformedURLException e) {
        e.printStackTrace();
    }

    socket.emit("sensorChanged", "argument1");

When i connect to the server, server doesnt say "socket.name connected", and doesnt emit event 'sensorChanged'. Where is the problem?

Answer 1

I also had connectivity issues when connecting Android app with Socket.IO with my server on the same WiFi (despite the fact that the connection worked when I tried to connect to the same URL in browser).

I found the solution here: https://stackoverflow.com/a/50834600/9560885

In short, try adding this line to your AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest ...>
    <uses-permission android:name="android.permission.INTERNET" />
    <application
        ...
        android:usesCleartextTraffic="true"
        ...>
        ...
    </application>
</manifest>

Answer 2

Use IP address: 10.0.2.2 for AVD & 10.0.2.3 for genymotion.

If you are using an external device on the same network, then use your server machine's local IP address.

Answer 3

Establishing Socket.IO Connection from Android Device to Local Node Server

---

A. Make sure you've installed socket.io-client-java via gradle.

---

B. Make sure you've enable internet access for your device.

<!-- AndroidManifest.xml -->

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="...">

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

    <application ...>
        ...
    </application>
</manifest>

---

C. Make sure the port you're running the server on is open.

• Open Port on Windows 10
• Open Port on Mac OSX 10

---

D. Connect to your local server using your computers network ip address.

• Open a terminal.
• Enter the command ipconfig.
• Look for your IPv4 Address.

You want to connect to http://<IPv4 Address>:<port>.

Connecting to localhost via http://localhost:3000 will not work because 'localhost' refers to the device itself.

---

E. Test the connection on your device.

• Set up a simple route on your server GET /status that just returns 200.
• Navigate to http://<IPv4 Address>:<port>/status on your device.
• If you get a success response, you should be good to go.

---

F. You should now be able to connect your android socket client to your node socket server.

// Node.js App

let SocketIO = require('socket.io');

let ioServer = SocketIO(server);
console.log('Socket Server waiting for connections');

ioServer.on('connection', function (socket) {
    console.log(`Socket Client connected with id=${socket.id}`);
});

-

// Android App

import io.socket.client.Socket;
import io.socket.client.IO;
import io.socket.emitter.Emitter;
import android.util.Log;

public class SocketIO implements Runnable {
    @Override
    public void run() {

        final Socket socket;

        try {
            socket = IO.socket("http://<IPv4 Address>:<port>");

            socket.on(Socket.EVENT_CONNECT, new Emitter.Listener() {

                @Override
                public void call(Object... args) {
                    Log.d("TAG", "Socket Connected!");
                    socket.disconnect();
                }

            });

        } catch(Exception e){
            Log.e("Error", e.toString());
        }

    }
}

Answer 4

Sorry for the late answer, I've just found the same condition, which makes me confused about what should I'm doing to solve this weird condition

All I did to solve this problem is just changing the version of the socket.io of the node server on your package.json

from

"dependencies": {
  "express": "^4.17.1",
  "socket.io": "^3.1.1"
}

to

"dependencies": {
  "express": "^4.17.1",
  "socket.io": "^1.7.2"
}

then delete the node_modules and execute npm install, or you can do any kind of way for decreasing the socket.io to ^1.7.2 version

Answer 5

Check this out, worked for me with the line below:

opts.transports = new String[]{"websocket"};

https://stackoverflow.com/a/67978895/6909832

Answer 6

My android application and nodejs was just connecting but not sending or receiving anything, then i have solved this issue by downgrading from

2.0.0 to 0.8.3 version in gradle file

implementation ('io.socket:socket.io-client:2.0.0') { 
    exclude group: 'org.json', module: 'json'
}

to

implementation ('io.socket:socket.io-client:0.8.3') { 
    exclude group: 'org.json', module: 'json'
}

and it worked for me

Answer 7

You are targeting Node server on your local machine from android. Since node does not run on Android (as far as I know) I am guessing you wanted to target the server on your pc. Instead of localhost(which in this Android code would refer to phone/tablet itself) you should use the network address of your pc in your local network.