Mohanraj
INSTANT
MESSENGER
AIM
To write a java program for creating Instant Messenger
application for communication between multiple clients.
ALGORITHM
Step
1: Start the process.
Step
2: Create the client module as class
Client by extending thread
class.
Step
3: Create the Server module as class Server for accepting
connection
from clients.
Step
4: Create ClientThread class in Server module to make 10 clients
to
communuicate.
Step
5: Start the Server.
Step
6: After Server is ready, then run the clients to communicate with
each other.
Step
6: Terminate the clients and Server respectively.
Step
7: Stop the process.
Source Code
Client.java
import
java.io.*;
import
java.net.*;
public class Client implements
Runnable
{
static Socket socket=null;
static PrintStream output;
static BufferedReader input=null;
static BufferedReader userip=null;
static boolean flag=false;
public static void main(String[] args)
{
int port=1234;
String host="localhost";
try
{
socket=new Socket(host,port);
userip=new BufferedReader(new
InputStreamReader(System.in));
output=new
PrintStream(socket.getOutputStream());
input=new BufferedReader(new
InputStreamReader(socket.getInputStream()));
}
catch(Exception e)
{
System.err.println("Unknown
host"+host);
}
if(socket!=null)
{
try
{
new Thread(new
Client()).start();
while(!flag)
{
output.println(userip.readLine());
}
output.close();
input.close();
socket.close();
}
catch(Exception e1)
{
System.err.println("IOException"+e1);
}
}
}
public void run()
{
String msg;
try
{
while((msg=input.readLine())!=null)
System.out.println(msg);
flag=true;
}
catch(IOException e)
{
System.err.println("IOException"
+ e);
}
}
}
Server.java
import java.io.*;
import java.net.*;
public class Server
{
static
ServerSocket server=null;
static Socket
socket=null;
static
ClientThread th[]=new ClientThread[10];
public static void
main(String args[])
{
int
port=1234;
System.out.println("Server
started...");
System.out.println(" [Press Ctrl C to terminate ]");
try
{
server=new
ServerSocket (port);
}
catch(IOException
e)
{
System.out.println("Exception
for Input/Output");
}
while(true)
{
try
{
socket=server.accept();
for(int
i=0;i<=9;i++)
{
if(th[i]==null)
{
(th[i]=new
ClientThread(socket,th)).start();
break;
}
}
}
catch(IOException
e)
{
System.out.println("Exception
for Input/Output");
}
}
}
}
class ClientThread
extends Thread
{
BufferedReader
input=null;
PrintStream
output=null;
Socket
socket=null;
ClientThread
th[];
public
ClientThread(Socket socket,ClientThread[] th)
{
this.socket=socket;
this.th=th;
}
public void
run()
{
String
msg;
String
username;
try
{
input
= new BufferedReader(new InputStreamReader(socket.getInputStream()));
output
= new PrintStream(socket.getOutputStream());
output.println("What
is your Name?Enter it-");
username
= input.readLine();
output.println(username
+ ":Welcome to chat room.");
output.println("To
leave chat room type $$");
for
(int i = 0; i <= 9; i++)
if
(th[i] != null && th[i] != this)
th[i].output.println("------------A
new user arrived in chat Room:" + username);
while
(true)
{
msg
= input.readLine();
if
(msg.startsWith("$$"))
break;
for
(int i = 0; i <= 9; i++)
if
(th[i] != null)
th[i].output.println("<"
+ username + ">" + msg);
}
for
(int k = 0; k <= 9; k++)
if
(th[k] != null && th[k] != this)
th[k].output.println("------A
user Leaving chat Room:" + username + "--------");
output.println("Press
Ctrl C to return to prompt---");
for
(int j = 0; j <= 9; j++)
if
(th[j] == this)
th[j]
= null;
input.close();
output.close();
socket.close();
}
catch
(IOException e)
{
System.out.println("Exception
for Input/Output");
}
}
}
Posted in: JavaScript
3 comments:
Hi. I have tested out the code and it only works with local IPs. It seems that it doesn't recognize/doesn't want to connect with normal IPs. How can I make it work with normal IPs(not locally)?
Initialise host with the IP address (in this code change the "localhost" to the IP address) to connect it to normal IP in Client.java
Nice. Helped me a lot.
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