Need help with HTTP keep-alive

Question

Hi folks!
I have this very simple web server and I would like to add keep-alive support. I've been trying to get my head around it for a while and could need some help (I found this question in the archive, but those replies didn't help)...
This is my starting point (stripped down to the basics):
/* A listener thread that accept incoming requests by creating new request handlers */
public class HTTPListener implements Runnable
    private ServerSocket serverSocket;
    public HTTPListener(int port)
        // Try to create a server socket on specified port
        try
            serverSocket = new ServerSocket(port, 0);
        catch (IOException ex)
            System.err.println("Oops!");
    public void run()
        while (!Thread.interrupted())
            try
                // Listen on server socket until a request arrives
                Socket s = serverSocket.accept();
                // Create handler to service request
                RequestHandler h = new RequestHandler(s);
                new Thread(h).start();
            // Server socket closed when listening
            catch (SocketException ex)
                Thread.currentThread().interrupt();
            // Failed to close socket or failure during server socket accept
            catch (IOException ex)
                System.err.println("Failed to accept request");
        try
            serverSocket.close();
        catch (IOException ex)
            System.err.println("Hmpf...");
/* Handler that prints out requests and always answers with status 200 */
public class RequestHandler implements Runnable
    private Socket socket;
    public RequestHandler(Socket s)
        socket = s;
    public void run()
        System.out.println(">>> New request handler");
        try
            BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String str;
            while ((str = reader.readLine()) != null)
                System.out.println(str);
            sendDummyReplyWithKeepAlive();
            reader.close();
            socket.close();
        catch (IOException ex)
            System.err.println("Crap, got an exception!");
}When I run the server (which in reality has a little more to it) I never get more than one request printed for each ">>> New request handler", which is not surprising!
Now, with keep-alive support I expect to get consecutive requests from the same client printed by the same handler instance. What I have to do (as I've understood from my readings) is to modify the while loop in the request handler that reads from the socket so that it spins until the connection is closed by the client (or a keep-alive timeout occurs) and blocks while there is nothing to read.
Perhaps I'm being stupid now, but how do I actually do this?

Answer 1

ejp wrote:
and also an incorrect implementation of the timeout period. This code will still wait forever if no data arrives.You're right... actually I didn't mean to put that while loop there! What I meant was simply
if (!reader.ready())
    wait(keepAliveTimeout);
if (!reader.ready())
    break mainLoop;
// If we get here there is a new request to read...and I agree that it's ugly, that's why I'm asking you guys for help!
setSoTimeout() is of course a way to go... didn't think of that although I have kind of already added it to my code but with a different timeout. Thanks!
Last question then is:
does reader.readLine() block like reader.read(), or do I have to use the latter?
I would test for myself I could, but at the moment I can't...