jpquestionvector.java

自己写的轮询提问的小程序 新手刚学 多多指教 合乎哈

/*
JPQuestionVector stores questions so that various parts of the server can access them
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 SharedClasses;

import java.io.*;
import java.util.*;

public class JPQuestionVector {
    private Vector QuestionVector;
    private Vector Listeners;
    private final static int JPQ_SIGNATURE = 369638;
    
    public JPQuestionVector() {
        QuestionVector = new Vector();
        Listeners = new Vector();
    }
 
    public void newQuestion() {
        Question q = new Question("", "Yes", "No", "Maybe", "I don't know", "I need to ask my wife", "N/A", 15, QuestionVector.size() + 1, 6);

        QuestionVector.addElement(q);
        fireSyncEvent();
    }

    public void saveToFile(String filename) {
	Question q;
        int count = QuestionVector.size();
        int i = 0;

        try {
            FileOutputStream fos = new FileOutputStream(filename, false);
            
            //Create the JPQ signature;
            fos.write(intToBytes(JPQ_SIGNATURE));

            while (i < count) {
                q = (Question) QuestionVector.elementAt(i);
                fos.write(q.getBytes());
                i++;
            }

                
            fos.close();
        }
        catch (Exception e) {System.err.println ("Error writing to file");}
        

    }
    
    public boolean loadFromFile(String filename) {
        int BytesRead = 0;
        byte[] sbuf = new byte[40];
        byte[] bbuf;
        int qns, qs, as, bs, cs, ds, es, fs, tqs;
        
        try {
            FileInputStream fis = new FileInputStream(filename);

            fis.read(sbuf, 0, 4);
            if (bytesToInt(sbuf, 0) != JPQ_SIGNATURE) return false;

            QuestionVector.removeAllElements();
            
            while ((BytesRead = fis.read(sbuf, 0, 40)) > -1) {

                qns = bytesToInt(sbuf, 0);
                qs = bytesToInt(sbuf, 4);
                as = bytesToInt(sbuf, 8);
                bs = bytesToInt(sbuf, 12);
                cs = bytesToInt(sbuf, 16);
                ds = bytesToInt(sbuf, 20);
                es = bytesToInt(sbuf, 24);
                fs = bytesToInt(sbuf, 28);
                
                tqs = qns + qs + as + bs + cs + ds + es + fs;
                bbuf = new byte[40 + tqs];
                
                System.arraycopy(sbuf, 0, bbuf, 0, 40);

                BytesRead = fis.read(bbuf, 40, tqs);

                QuestionVector.addElement(new Question(bbuf));
                
                
                bbuf = null;
            }
            
            fis.close();
        }
        catch (Exception e) {System.err.println("File input error"); return false;}
        
        if (QuestionVector.size() <= 0) newQuestion();
        fireSyncEvent();
        return true;
    }

    public Question getQuestionAt(int index) {
        if (index > QuestionVector.size() - 1) return null;
        return (Question) QuestionVector.elementAt(index);
    }
    
    public void addQuestion(Question q) {
        QuestionVector.addElement(q);
        fireSyncEvent();
    }
    
    public void deleteQuestionAt(int index) {

        int i;
        int size = QuestionVector.size();
        Question q;
        
        if (size < 2) return;
       
        QuestionVector.removeElementAt(index);

        for (i = index; i < QuestionVector.size(); i++) {
            q = (Question) QuestionVector.elementAt(i);
            q.setQuestionNumber(i + 1);
        }

        fireSyncEvent();
    }
    
    public Vector getQuestionListing() {
        Question q;
        int i;
        int size = QuestionVector.size();
        Vector v = new Vector();
        
        for (i = 0; i < size; i++) {
            q = (Question) QuestionVector.elementAt(i);
            v.addElement(q.getQuestionName());
        }
        
        return v;
    }
    
    public Vector getVector() {
        return QuestionVector;
    }
    
    public int size() {
        return QuestionVector.size();
    }
    
    public void addListener(Syncable o) {
        Listeners.addElement(o);
    }
    
    public void removeListener(Syncable o) {
        Listeners.remove(o);
    }
    
    public void fireSyncEvent() {
        int i;
        int size = Listeners.size();
        Syncable s;
        
        for (i = 0; i < size; i++) {
            s = (Syncable) Listeners.elementAt(i);
            s.syncComboBoxes();
        }
    }
    
    public int getIndexOfQuestion(Question q) {
        return QuestionVector.indexOf(q);
    }
    
    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;
    }
    
    private byte[] intToBytes(int value) {
        byte [] bytes = new byte [4];

        bytes[0] = (byte)(value >> 24);
        bytes[1] = (byte)(value >> 16);
        bytes[2] = (byte)(value >> 8);
        bytes[3] = (byte)(value);
        return bytes;
        
    }
    
    public void deleteAllQuestions() {
        QuestionVector.removeAllElements();
        newQuestion();
        fireSyncEvent();
    }
}