Android套接字连接问题

Question

I am creating a chat application, which runs as a service. I connect to the chat server using a socket, and I declared a timeout using setSoTimeout .

When a connection is idle, (for example when I am at home and connected to WiFi) I never face issues. When I go outside, and my WiFi connection is lost, my phone switches to 3G. The problem is that the socket stays connected without receiving any data. (So the timeout exception isn't called.) < sometimes it connects after 30 mins, but this need to be reduced to at least a few seconds.

I also tried to add a CONNECTIVITY_CHANGE broadcast detector in my AndroidManifest.xml, this also didn't work.

See my socket connection below:

    socket = new Socket(proxy);
    SocketAddress socketAddress = new InetSocketAddress(HOST,
                PORT);
    socket.connect(socketAddress);
    if (socket.isConnected()) {
        socket.setSoTimeout(1020000); //Even when setting to 10000 makes no sense
        return true;
    } else {
        Log.w("WARNING", "Failed to connect to the server");
        return false;
    }

In the background there are also some loops running which checks the server for chatmessages, these loops triggers a reconnect when no data is received, but this didn't work too. (During reconnect, I set the socket to socket.close() and socket = null before connecting again.)

So are there any ideas, maybe I need to use a different socket? Or some other code to resolve this problem? Thanks.

Answer 1

In such unexpected(as per application's perspective) network disconnection, the socket won't know it was disconnected. If this situation occurs, the only way is to try writing some data to the socket. When the socket is disconnected, writing data would throw IOExcpetion with message like Connection reset .

You'd better implement a heartbeat method to detect the disconnection. A packet sent to server every 5~10 seconds would detect network disconnection speedy enough.