network.java

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/*
This is the network class of the PollClient. It handles all the network stuff
Copyright (C) 2005-2006  Igor Partola, Michael J. Krikonis, Clark University

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

package PollClient;

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

public class Network {
    private final static int BUFFER_SIZE = 4096*4;
    public final static int PORT_NUMBER = 6969;
    public final static byte CHECK_BYTE = 0;
    public final static byte CLIENT_SENDING_ANSWER = 100;
    public final static byte SERVER_SENDING_QUESTION = 1;
    public final static byte SERVER_DISCONNECTED = 10;
    public final static byte QUESTION_CLOSED = 11;
    public final static byte CONNECTION_TIMED_OUT = 2;
    private OutputStream out;
    private InputStream in;
    private Socket clntSock;
    
    public Network(String addr, int port) throws IOException {
        try {
            clntSock = new Socket(addr, port);
            clntSock.setSoTimeout(750);
            
            in = clntSock.getInputStream();
            out = clntSock.getOutputStream();

        } catch (UnknownHostException e) {
            System.out.println("Don't know about that host");
            throw e;
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to the server");
            throw e;
        }
    }
    
    public String arrayToString(byte[] b, int length) {
       return new String(b, 0, length);
    }
    
    public Question recieveQuestion() {
	byte[] bufA = new byte[BUFFER_SIZE];
//	byte[] bufB;
        
        try {
            int bytesRecieved = in.read(bufA);
            if (bytesRecieved < BUFFER_SIZE) return new Question(bufA);
/*            
            int qns = bytesToInt(bufA, 0);
            int qs = bytesToInt(bufA, 4);
            int as = bytesToInt(bufA, 8);
            int bs = bytesToInt(bufA, 12);
            int cs = bytesToInt(bufA, 16);
            int ds = bytesToInt(bufA, 20);
            
            int totalSizeOfQuestion = qns + qs + as + bs + cs + ds + 28;
            bufB = new byte[totalSizeOfQuestion];
            bytesRecieved = in.read(bufB, BUFFER_SIZE, totalSizeOfQuestion - BUFFER_SIZE);
            System.arraycopy(bufA, 0, bufB, 0, BUFFER_SIZE);
  */          
        }
        catch (IOException e) { 
            return null;
        }
        return new Question(bufA);
    }

    public void sendAnswer(int i) {
        try {
            out.write((byte) i);
        }
        catch (IOException e) { }
    }
    
    public void close() {
        try {
            clntSock.close();
        }
        catch (IOException e) {}
    }
    
    public byte checkForQuestionStatus() {
        byte[] b = new byte[1];
        b[0] = -1;
        int BytesRead = 0;
        
        try {
            BytesRead = in.read(b);
            if (BytesRead > 0) {
                switch (b[0]) {
                    case CHECK_BYTE: out.write(CHECK_BYTE); return CHECK_BYTE;
                    default: return b[0];
                    
                }
                    
            }
        }
        catch (IOException e) { 
            return CONNECTION_TIMED_OUT;
        }
        
        return CONNECTION_TIMED_OUT;
    }
 
    private static int bytesToInt(byte[] b, int offset) {
        int value = 0;
        for (int i = 0; i < 4; i++) {
            int shift = (4 - 1 - i) * 8;
            value += (b[i + offset] & 0x000000FF) << shift;
        }
        return value;
    }
    
}