Examples: Change your Java code to use server socket factories

These examples show you how to change a simple socket class, named simpleSocketServer, so that it uses socket factories to create all of the sockets. The first example shows you the simpleSocketServer class without socket factories. The second example shows you the simpleSocketServer class with socket factories. In the second example, simpleSocketServer is renamed to factorySocketServer.

Example 1: Socket server program without socket factories

Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.

/* File simpleSocketServer.java*/

import java.net.*;
import java.io.*;

public class simpleSocketServer {
  public static void main (String args[]) throws IOException {

    int serverPort = 3000;

    if (args.length < 1) {
      System.out.println("java simpleSocketServer serverPort");
      System.out.println("Defaulting to port 3000 since serverPort not specified.");
    }
    else
        serverPort = new Integer(args[0]).intValue();

    System.out.println("Establishing server socket at port " + serverPort);
    
    ServerSocket    serverSocket =
      new ServerSocket(serverPort);

    // a real server would handle more than just one client like this...

    Socket s = serverSocket.accept();
    BufferedInputStream is = new BufferedInputStream(s.getInputStream());
    BufferedOutputStream os = new BufferedOutputStream(s.getOutputStream());

    // This server just echoes back what you send it...

    byte buffer[] = new byte[4096];

    int bytesRead;

    // read until "eof" returned
    while ((bytesRead = is.read(buffer)) > 0) {
      os.write(buffer, 0, bytesRead); // write it back
      os.flush();    // flush the output buffer
    }


    s.close();
    serverSocket.close();
  }       // end main()

}       // end class definition

Example 2: Simple socket server program with socket factories

Note: Read the Code example disclaimer for important legal information.

/* File factorySocketServer.java */

// need to import javax.net to pick up the ServerSocketFactory class
import javax.net.*;
import java.net.*;
import java.io.*;

public class factorySocketServer {
  public static void main (String args[]) throws IOException {

    int serverPort = 3000;

    if (args.length < 1) {
      System.out.println("java simpleSocketServer serverPort");
      System.out.println("Defaulting to port 3000 since serverPort not specified.");
    }
    else
        serverPort = new Integer(args[0]).intValue();

    System.out.println("Establishing server socket at port " + serverPort);

    // Change the original simpleSocketServer to use a
    // ServerSocketFactory to create server sockets.
    ServerSocketFactory serverSocketFactory =
      ServerSocketFactory.getDefault();
    // Now have the factory create the server socket.  This is the last
    // change from the original program.
    ServerSocket    serverSocket =
      serverSocketFactory.createServerSocket(serverPort);

    // a real server would handle more than just one client like this...

    Socket s = serverSocket.accept();
    BufferedInputStream is = new BufferedInputStream(s.getInputStream());
    BufferedOutputStream os = new BufferedOutputStream(s.getOutputStream());

    // This server just echoes back what you send it...

    byte buffer[] = new byte[4096];

    int bytesRead;

    while ((bytesRead = is.read(buffer)) > 0) {
      os.write(buffer, 0, bytesRead); 
      os.flush();    
    }


    s.close();
    serverSocket.close();
  }       

}

For background information, see Change your Java™ code to use socket factories.