Client Server Application in Java

This Java program is about how to implement a client server application in Java. A client /server application is a piece of software that runs on client system and make request to a remote server. First Run the server main class to active the server. After running the server start listening the request from client side. Now run the the client main class that send a message to server to connect and start chat. Here is the complete source code of this program which help you in better understanding.

Source Code

Server.Java

package TCPserverApplication;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class server {
 public void simple_server() throws Exception{
  Scanner in = new Scanner(System.in);
  try{
   ServerSocket server = new ServerSocket( 11111 , 1 , InetAddress.getByName("localhost"));//server will listen on port 11111
   String message_for_client="go";
   String sendMessage;
   
   while(true)//The server will continue to listen for another client.
   {
    System.out.println("Waiting for request . . .");
    Socket client1 = server.accept();
    System.out.println("Accepted go on client cosole");  
    
    while(!(message_for_client=="exit"))
    {
     if(!client1.isClosed()){
      InputStream input_stream = client1.getInputStream();
            InputStreamReader input_stream_reader = new InputStreamReader(input_stream );
            BufferedReader buffer_reader = new BufferedReader(input_stream_reader);
            String message = buffer_reader.readLine();
            
            if(message==null){
             System.out.println("Exited");//Server receives the message and displays on the screen
             client1.close();
            }else{
             System.out.println("From Client : "+message);//Server receives the message and displays on the screen
             
             OutputStream output_stream = client1.getOutputStream();
             OutputStreamWriter output_stream_writer= new OutputStreamWriter(output_stream);
             BufferedWriter buffered_writer = new BufferedWriter(output_stream_writer);
             
             System.out.println("Enter a message for Client:");
             
             message_for_client = in.nextLine();//server takes input from the keyboard and sends this to the client.
       
             sendMessage = message_for_client + "\n";
            
             buffered_writer.write(sendMessage);
             buffered_writer.flush();
            }
        }else{
         client1.close();
         break;
        }
    }
    
   }
   
  }
  catch (Exception e){
   e.printStackTrace();
  }
  in.close();
 }
}

Server_main.Java

package TCPserverApplication;

/*
 * CMS : 7667
 * Name : Uzair Ahmed
 * Topic : TCP Client and TCP Server application
 */
public class server_main {
 public static void main(String[] args) throws Exception {
   System.out.println("Welcome Server");
   server s=new server();
   
   s.simple_server();
   
 }
}

Client.Java

package TCPclientApplications;
//SimpleClient.java: A simple client program.
import java.net.*;
import java.util.Scanner;
import java.io.*;
public class client {
 public void simple_client() throws Exception{
  
  Socket client_socket = new Socket(InetAddress.getByName("localhost"),11111);
  
  Scanner in = new Scanner(System.in);
  String message_from_server;
  String message_for_server="go";
  String sendMessage;
        while(!(message_for_server=="exit"))
        {
      OutputStream output_stream = client_socket.getOutputStream();
         OutputStreamWriter output_stream_writer= new OutputStreamWriter(output_stream);
         BufferedWriter buffered_writer = new BufferedWriter(output_stream_writer);
         
         System.out.println("Enter a message for Server:");
         message_for_server = in.nextLine();// the client takes input from the keyboard and sends this message to server.
         if(message_for_server.equals("exit")){//On EXIT, the client closes its connection and terminates.
          System.out.println("EXITING");
          client_socket.close();
          System.exit(0);
          
         }
         sendMessage = message_for_server + "\n";
         
         buffered_writer.write(sendMessage);
         buffered_writer.flush();
         
         InputStream input_stream = client_socket.getInputStream();
         InputStreamReader input_stream_reader = new InputStreamReader(input_stream);
         BufferedReader buffered_reader = new BufferedReader(input_stream_reader );
         
         message_from_server = buffered_reader.readLine();
         System.out.println("Server : " +message_from_server);//Client receives the message and displays on the screen
        }
        
  in.close();
  client_socket.close();
 }
}

Client_main.Java

package TCPclientApplications;

/*
 * CMS : 7667
 * Name : Uzair Ahmed
 * Topic : TCP Client and TCP Server application
 */
public class client_main {
 public static void main(String[] args) throws Exception {
   System.out.println("Welcome Client");
   client c=new client();
   
   c.simple_client();
   
 }
}

Output of the Program

Client /Server Application in Java

About Asad

Asad Niazi is Software Engineer , Programmer, Web Developer and a young mentor of BloggersTown and PProgramming. Asad Love to writes about Technology, Programming, Blogging and make money online.