Java Socket handshaking: the simplest example

In an earlier post, I have discussed how to implement socket communication with python. I recently was asked to implement similar functions, but in Java. Here is how I did that.

• Create a new Java project, let’s name it JSocketClient;
• Create another Java project, let’s name it JSocketServer;
• In both projects, create an App class, and add a static Main function respectively:

• In the Client project, add a class JSocketClient:

       private Socket _client;
    private String _ServerName = “localhost”;
    private int _port = 8089;
   
    _client = new Socket(_ServerName, _port);

public void SendString(String data) {         if (_client == null) {             System.out.println(“Client:\tEmpty Socket client. Please retry”);             return;         }         OutputStream oStream;         try {             System.out.println(“Client:\tSending data:” + data);             oStream = _client.getOutputStream();             DataOutputStream out = new DataOutputStream(oStream);             out.writeUTF(data);                    } catch (IOException e) {             e.printStackTrace();         }     }

• In the server project, add a class JSocketServer:

import java.io.DataInputStream; import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; import java.net.SocketTimeoutException; public class JSocketServer extends Thread {     private ServerSocket serverSocket;     public JSocketServer(int port) {         try {             serverSocket = new ServerSocket(port);             serverSocket.setSoTimeout(10000);         } catch (IOException e) {                        e.printStackTrace();         }     }     public void run() {         while (true) {             try {                 System.out.println(“Server:\tWaiting for client on port “                         + serverSocket.getLocalPort() + “…”);                                Socket server = serverSocket.accept();                                System.out.println(“Server:\tJust connected to “                         + server.getRemoteSocketAddress());                                DataInputStream in = new DataInputStream(                         server.getInputStream());                 System.out.println(“Server:\t\t Got Data: ” + in.readUTF());                                            server.close();                            } catch (SocketTimeoutException s) {                 System.out.println(“Socket timed out!”);                 break;             } catch (IOException e) {                 e.printStackTrace();                 break;             }         }     } }

1. Run the server project, where in the main() function:

   public class App {     public static void main(String[] args) {         JSocketServer t = new JSocketServer(8089);         t.start();     } }

2. Run the client project, where in the main() function:
   

   public class App {     static JSocketClient client;     public static void main(String[] args) {           client=new JSocketClient();             } }

That is it! Now let’s see the result in console of Eclipse:

That is it. Happy coding.