cannot keep socket connection when screen off in android

问题

I have trouble to keep socket connection in android.

I use Socket.IO-client java library in my application.

The socket connection is keeped when screen on.

but, if screen off, the socket is disconnected caused by ping timeout.

how can i solve this problem?

I open connection like this.

private static final String EVENT_CONNECT = Socket.EVENT_CONNECT;
private static final String EVENT_MESSAGE = Socket.EVENT_MESSAGE;
private static final String EVENT_DISCONNECT = Socket.EVENT_DISCONNECT;
private static final String EVENT_PING = Socket.EVENT_PING;
private static final String EVENT_CONNECT_TIMEOUT = Socket.EVENT_CONNECT_TIMEOUT;
private static final String EVENT_ERROR = Socket.EVENT_ERROR;

public void connect() {
    if (socket != null && socket.connected() == true) {
        return;
    }
    IO.Options options = new IO.Options();

    options.timeout = 60 * 1000;
    options.reconnection = true;

    Log.d(TAG, "try socket connect");
    socket.on(EVENT_CONNECT, this::onConnected)
            .on(EVENT_MESSAGE, this::onMessage)
            .on(EVENT_DISCONNECT, this::onDisconnected)
            .on(EVENT_PING, this::onPing)
            .on(EVENT_CONNECT_TIMEOUT, this::onConnectTimeout)
            .on(EVENT_ERROR, this::onError);

    socket.connect();
}

And this is my server side code

var Socket = require('socket.io');
var io = Socket(server, { 'pingInterval': 25 * 1000 });
var port = process.env.PORT || 3000;

io.on('connection', function(socket){
    console.log('a user connected');

    ...

    socket.on('disconnect', function(data){
        (typeof socket.member != 'undefined') && disconnect(socket);
        console.log(data);
    });
});

ping interval is 25 second, and timeout is 60 second.

when android screen is off, client do not work for EVENT_PING. the other event work correctly.

and server is disconnected with log(ping timeout).

回答1:

I solve this problem like below:

private static final String EVENT_PING = "ping1";
private static final String EVENT_PONG = "pong1";

public void connect() {
    if (socket != null && socket.connected() == true) {
        return;
    }
    IO.Options options = new IO.Options();

    options.timeout = 60 * 1000;
    options.reconnection = true;

    Log.d(TAG, "try socket connect");
    socket.on(EVENT_CONNECT, this::onConnected)
            .on(EVENT_MESSAGE, this::onMessage)
            .on(EVENT_DISCONNECT, this::onDisconnected)
            .on(EVENT_PING, this::onPing)
            .on(EVENT_CONNECT_TIMEOUT, this::onConnectTimeout)
            .on(EVENT_ERROR, this::onError);

    socket.connect();
}

private void onPing(Object... args) {
    Log.d(TAG, "socket ping");
    socket.emit(EVENT_PONG);
}

This is server code.

var pingInterval = 25 * 1000;
var Socket = require('socket.io');
var io = Socket(server, { 'pingInterval': pingInterval });
var port = process.env.PORT || 3000;

io.on('connection', function(socket){
    console.log('a user connected');

    function sendPing() {
        socket.emit('ping1');
    }

    setTimeout(sendPing, pingInterval);

    socket.on('disconnect', function(data){
        (typeof socket.member != 'undefined') && disconnect(socket);
        console.log(data);
    });

    socket.on('pong1', function(data) {
        setTimeout(sendPing, pingInterval);
        console.log('pong');
    });
});

来源：https://stackoverflow.com/questions/36301291/cannot-keep-socket-connection-when-screen-off-in-android