SocketListener

package preiss;

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

 

public class SocketListener extends Thread  {

   public static final int PORT_NUMBER = 4241;
   protected Socket socket;


   public static void main(String[] args) {
      ServerSocket server = null;
      try {
         server = new ServerSocket(PORT_NUMBER);
         while (true) {
            new SocketListener(server.accept());
         }
      }

      catch(IOException ex) {
         System.out.println("Unable to start server or accept connections");
         System.exit(1);

      }

      finally {
         try {
            server.close();
         }
         catch(IOException ex) {
            // not much can be done: log the error
            // exits since this is the end of main
         }
      }
   }
 

   private SocketListener(Socket socket) {
      this.socket = socket;
      start();
   }

 

   // the server services client requests in the run method

   public void run() {
      InputStream in = null;
      OutputStream out = null;
      try {
         in = socket.getInputStream();
         out = socket.getOutputStream();

 		String replyString = this.message;
	    try {

	    	byte[] b = wrap(replyString.getBytes()); //not necessary in general. was used for a project where the message lenght had to be sent in the message.
	    	out.write(b);
	    	out.flush();
	    	out.close();

	    } catch (IOException e1) {
	      System.out.println(e1.getMessage());
	    } catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

      }

      catch(IOException ex) {
         System.out.println("Unable to get streams from client");
      }

      finally {
         try {
            in.close();
            out.close();
            socket.close();
         }
         catch(IOException ex) {
            // not much can be done: log the error
         }
      }
   }

   public byte[] wrap(byte[] msg) throws Exception {
	   int len = msg.length;
	   if (len > 65535) {
	   throw new IllegalArgumentException("Exceeds 65535 bytes.");
	   }
	   byte firstByte = (byte)(len >>> 8);
	   byte secondByte = (byte)len;
	   ByteArrayOutputStream baos = new ByteArrayOutputStream(len + 2);
	   baos.write(firstByte);
	   baos.write(secondByte);
	   baos.write(msg);
	   return baos.toByteArray();
	   }
   
	
	String message=new String("<message>MessageContents</message>");
   
}