UDP socket chat application in java -
i'm trying create simple chat application in java using udp sockets. there 1 server , multiple clients.
right code :
server :
package chat; import java.io.*; import java.net.*; import java.util.hashmap; import java.util.set; class user{ inetaddress addr; int port; user(inetaddress a,int p){ addr = a; port = p; } } public class server { private static final int port = 27012; private static datagramsocket sckt; private static datagrampacket in,out; private static byte[] buffer; private static hashmap<string,user> users; public static void main(string[] args) { try{ system.out.println("opening port..."); sckt = new datagramsocket(port); users = new hashmap<string,user>(); } catch(socketexception e){ system.out.println("port connection failed!"); system.exit(1); } handleclient(); } private static void sendmsg(inetaddress addr, int port, string msg){ try{ out = new datagrampacket(msg.getbytes(),msg.length(),addr,port); sckt.send(out); }catch(ioexception e){ e.printstacktrace(); } } private static void handleclient(){ try{ string msgin,msgout="",sendernick; do{ buffer = new byte[256]; in = new datagrampacket(buffer,buffer.length); sckt.receive(in); inetaddress clientaddress = in.getaddress(); int clientport = in.getport(); msgin = new string(in.getdata(),0,in.getlength()); //print msgin //system.out.println(msgin); sendernick = msgin.substring(0,msgin.indexof(" ")); msgin = msgin.substring(msgin.indexof(" ")+1); if(msgin.equals("/connect")){ //string nick = msgin.substring(msgin.indexof(" ") + 1); system.out.println(sendernick); if(users.containskey(sendernick)){ msgout = "nick in use!"; } else{ users.put(sendernick, new user(clientaddress,clientport)); msgout = "connected!"; } sendmsg(clientaddress,clientport,msgout); } else if(msgin.equals("/list")){ set usernames; usernames = users.keyset(); msgout = "users : \n"; msgout += usernames.tostring(); sendmsg(clientaddress,clientport,msgout); } else if(msgin.startswith("/msg")){ string tmp = msgin.substring(msgin.indexof(" ")+1); string receivername = tmp.substring(0,tmp.indexof(" ")); string message = tmp.substring(tmp.indexof(" ")+1); if(!users.containskey(receivername)){ msgout = "user " + receivername + " not found!"; sendmsg(clientaddress,clientport,msgout); } else{ user receiver = users.get(receivername); msgout = "message "+ sendernick +" : "+message; sendmsg(clientaddress,clientport,"message sent!"); sendmsg(receiver.addr,receiver.port,msgout); } } else if(msgin.startswith("/nick")){ string newnick = msgin.substring(msgin.indexof(" ")+1); if(users.containskey(newnick)){ msgout = "nick in use!"; } else{ users.put(newnick,users.get(sendernick)); users.remove(sendernick); msgout = "nick changed!"; } sendmsg(clientaddress,clientport,msgout); } else if(msgin.equals("/disconnect")){ users.remove(sendernick); } //out = new datagrampacket(msgout.getbytes(),msgout.length(),clientaddress,clientport); //sckt.send(out); }while(true); } catch(ioexception e){ e.printstacktrace(); } finally{ system.out.println("closing connection."); sckt.close(); } } } client :
package chat; import java.io.*; import java.net.*; import java.util.scanner; public class client { private static inetaddress host; private static final int port = 27012; private static datagramsocket sckt; private static datagrampacket in, out; private static byte[] buffer; private static string nick; static class messagelistener implements runnable { //datagrampacket in; //byte[] buffer; string reply; public void run() { do{ try{ buffer = new byte[256]; in = new datagrampacket(buffer,buffer.length); sckt.receive(in); reply = new string(in.getdata(),0,in.getlength()); system.out.println("server> "+reply); } catch(ioexception e){ e.printstacktrace(); } }while(true); } } public static void main(string[] args) { try { host = inetaddress.getlocalhost(); } catch (unknownhostexception e) { system.out.println("host not found!"); system.exit(1); } connect(); } private static void sendmsg(string msg) { try { out = new datagrampacket(msg.getbytes(), msg.length(), host, port); sckt.send(out); } catch (ioexception e) { e.printstacktrace(); } } private static void connect() { scanner sc = new scanner(system.in); try { buffer = new byte[256]; sckt = new datagramsocket(); string reply = ""; { system.out.println("name: "); nick = sc.nextline(); sendmsg(nick + " /connect"); in = new datagrampacket(buffer, buffer.length); sckt.receive(in); reply = new string(in.getdata(), 0, in.getlength()); system.out.println("server> " + reply); } while (!reply.equals("connected!")); accessserver(); } catch (ioexception e) { e.printstacktrace(); } } private static void accessserver() { try { sckt = new datagramsocket(); scanner sc = new scanner(system.in); string msg = "", reply = ""; thread myt = new thread(new messagelistener()); myt.start(); { system.out.print("enter message: "); msg = sc.nextline(); if (!msg.equals("/quit")) { buffer = new byte[256]; sendmsg(nick + " " + msg); } else { sendmsg(nick + " /disconnect"); } } while (!msg.equals("/quit")); sc.close(); } catch (ioexception e) { e.printstacktrace(); } { system.out.println("connection closing..."); sckt.close(); } } } i want able send message single user or users problem can't receive message on client because stands client receives message after sends 1 server. thought use thread continuosly listens messages server doesn't work. what's easiest way go ?
you attempting use received datagram immediately, instead of waiting thread created receive datagram , populate in variable. either handle received datagram directly in thread's code, or signal main thread when datagram received using wait() / notify() scheme.
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