Problem with a blocking network task
- by user326967
Hello everyone.
I'm new in Java so please forgive any obscene errors that I may make :)
I'm developing a program in Java that among other things it should also handle clients that will connect to a server. The server has 3 threads running, and I have created them in the following way :
DaemonForUI du;
DaemonForPort da;
DaemonForCheck dc;
da = new DaemonForPort(3);
dc = new DaemonForCheck(5);
du = new DaemonForUI(7);
Thread t_port = new Thread(da);
Thread t_check = new Thread(dc);
Thread t_ui = new Thread(du);
t_port.setName("v1.9--PORTd");
t_check.setName("v1.9-CHECKd");
t_ui.setName("v1.9----UId");
t_port.start();
t_check.start();
t_ui.start();
Each thread handles a different aspect of the complete program. The thread t_ui is responsible to accept asynchronous incoming connections from clients, process the sent data and send other data back to the client. When I remove all the commands from the previous piece of code that has to with the t_ui thread, everything runs ok which in my case means that the other threads are printing their debug messages.
If I set the t_ui thread to run too, then the whole program blocks at the "accept" of the t_ui thread.
After reading at online manuals I saw that the accepted connections should be non-blocking, therefore use something like that :
public ServerSocketChannel ssc = null;
ssc = ServerSocketChannel.open();
ssc.socket().bind(new InetSocketAddress(port));
ssc.configureBlocking(false);
SocketChannel sc = ssc.accept();
if (sc == null) {
;
}
else {
System.out.println("The server and client are connected!");
System.out.println("Incoming connection from: " + sc.socket().getRemoteSocketAddress());
in = new DataInputStream(new BufferedInputStream(sc.socket().getInputStream()));
out = new DataOutputStream(new BufferedOutputStream(sc.socket().getOutputStream()));
//other magic things take place after that point...
The thread for t_ui is created as follows :
class DaemonForUI implements Runnable{
private int cnt;
private int rr;
public ListenerForUI serverListener;
public DaemonForUI(int rr){
cnt = 0;
this.rr = rr;
serverListener = new ListenerForUI();
}
public static String getCurrentTime() {
final String DATE_FORMAT_NOW = "yyyy-MM-dd HH:mm:ss";
Calendar cal = Calendar.getInstance();
SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW);
return (sdf.format(cal.getTime()));
}
public void run() {
while(true) {
System.out.println(Thread.currentThread().getName() + "\t (" + cnt + ")\t (every " + rr + " sec) @ " + getCurrentTime());
try{
Thread.sleep(rr * 1000);
cnt++;
}
catch (InterruptedException e){
e.printStackTrace();
}
}
}
}
Obviously, I'm doing something wrong at the creation of the socket or at the use of the thread. Do you know what is causing the problem?
Every help would be greatly appreciated.
