Java Client-Server Example

Server

Here is a short example of a server written in Java. You will find the matching client further down in the page.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class ServerExample {

 public void startItUp(){
      ServerSocket aServerSocket = null;
      try {
	aServerSocket = new ServerSocket(7070);
   } catch (IOException e1) {
	e1.printStackTrace();
	return;
   }
   boolean keepGoing = true;
   while(keepGoing){
      try {
          System.out.println("Waiting for connection.");
	  Socket aClientSocket = aServerSocket.accept();
	  System.out.println("Connection made from a client.");
	  BufferedReader fromClient = new BufferedReader(
                        new InputStreamReader(aClientSocket.getInputStream()));
	  PrintWriter toClient = new PrintWriter(aClientSocket.getOutputStream(),
                                                                               true);
	  String messageString = null;
	  while((messageString = fromClient.readLine()) != null){
	     String responseString = messageString + "   -------Is this for real?-------";
	     toClient.println(responseString);
	  }
        } catch (Exception e) {
	  e.printStackTrace();
	}
   }
 }
 public static void main(String[] args) {
    ServerExample aServer = new ServerExample();
    aServer.startItUp();
 }
}

Client

Here is the client code that goes with the server shown above.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

public class ClientExample {

	public void talkBack(){
		BufferedReader fromUser = new BufferedReader(
                             new InputStreamReader(System.in));
		Socket aSocket = null;
		PrintWriter toServer = null;
		BufferedReader fromServer = null;
		try {
			System.out.println("Connecting.");
			aSocket = new Socket("localhost", 7070);
			fromServer = new BufferedReader(
                                         new InputStreamReader(aSocket.getInputStream()));
			toServer = new PrintWriter(aSocket.getOutputStream(),
                                                                         true);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return;
		}
		System.out.println("Connected.\n\nPlease enter a string to to send to the server:\n");
		String fromUserString = null;
		try{
			while((fromUserString = fromUser.readLine()) != null){
				toServer.println(fromUserString);
				String result = fromServer.readLine();
				System.out.println(result);
			}
		}
		catch(Exception e){
			e.printStackTrace();
			return;
		}
	}
	public static void main(String[] args) {
		ClientExample aClient = new ClientExample();
		aClient.talkBack();
		System.out.println("\n\n\nDone.");
	}
}