SecureClientHandler.java

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.io.IOException;

public class SecureClientHandler extends Thread {

 private Socket socket;
 private SecureServer owner;
 private ObjectInputStream inputStream;
 private ObjectOutputStream outputStream;

 /**
    * A wrapper for every client that connects to the server. Handles messages being sent to other clients and sends server messages back to the client
    * @param   The socket that holds the connection to the client
    * @param   The server that is currently using this SecureClientHandler
    */
 public SecureClientHandler(Socket clientSocket, SecureServer owner) {
     this.socket = socket;
     this.owner = owner;
     try {
         this.inputStream = new ObjectInputStream(socket.getInputStream());
         this.outputStream = new ObjectOutputStream(socket.getOutputStream());
     } catch (IOException e) {
         e.printStackTrace();
     }

 }

 /**
    * Runs the thread and listens for any messages coming in from the client
    */
 public void run() {
     while(true) {
         SecureMessage fromClient = null;

         try {
             fromClient = (SecureMessage) inputStream.readObject();
         } catch(Exception e) {
             System.out.println(e.getStackTrace());
         }

         if ( fromClient != null ) {
             if( fromClient.getType().equals("MESSAGE")) {
                 SecureMessage toClient = new SecureMessage(fromClient.getMessage(),MessageType.MESSAGE,fromClient.getReceiver(),fromClient.getSender());
                 SecureClientHandler receiver = null;

                 try {
                     receiver = owner.resolveClientHandler(fromClient.getReceiver());
                 } catch(ClientNotFoundException e) {
                     e.printStackTrace();
                 }

                 if(receiver != null ) {
                     receiver.sendMessage(toClient);
                 }
             } else {

                 try {
                     socket.close(); // Apparently the client disconnected or there was an error on the client side
                 } catch (IOException e) {
                     e.printStackTrace();
                 }

                 owner.disconnect(this,fromClient.getType()); // TODO: Send a server message to all affected clients
             }
         }
     }
 }

 /**
    * Queues a message from the server to be sent to the client (e.g. server restarts or client dropped connection)
    * @param message   The message that should be sent to the client
    */
 public void queueMessage(String message) {
     // TODO: Send server message to client;
 }

 public void sendMessage(SecureMessage message) {
     try {
         outputStream.writeObject(message);
     } catch (IOException e) {
         e.printStackTrace();
     }

 }

 /**
    * Returns the socket of the SecureClientHandler
    * @return A socket
    */
 public Socket getSocket() {
     return this.socket;
 }
}