Android socket io获取在线用户

Question

I am developing an Android private chat application. In this application, I want to see the online user or check whether the user is online or not. I have got the reference.

emit("login",userid);

is used for get online users. So I use

public class OnlineActivity extends AppCompatActivity {
    private Socket mSocket;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_online);

        ChatApplication app = (ChatApplication) getApplication();
        mSocket = app.getSocket();

        JSONObject user = new JSONObject();
        try {
            user.put("userId", "abc");
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        mSocket.emit("login",user);

        Log.d("LOG", String.valueOf(mSocket.emit("login",user)));
        Log.d("LOG", String.valueOf(user));
    }
}

where abc is user id, but it does not show any results. Please help me.

Answer 1

The answer is shown in How to check a user online or not in socket io and android chat application

socket.on('isActive', function (user) {
const userId = user.userId;
const user = usernames[userId];
const socketId = socket.id;
let response;
if(user) {
    // User is active
    response = {isActive: true};
} else {
    // User is not active
    response = {isActive: false};
}
const responseSocket = io.sockets.connected[socketId];
if(responseSocket) {
    responseSocket.emit('onIsActive', response);
}
});