AdaptiveRandomWordFactory.java

/*
 * Copyright (c) 2009 Piotr Piastucki
 * 
 * This file is part of Patchca CAPTCHA library.
 * 
 *  Patchca is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *  
 *  Patchca 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 Lesser General Public License for more details.
 *  
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with Patchca. If not, see <http://www.gnu.org/licenses/>.
 */
package com.xiongyingqi.captcha.word;

import java.util.Random;

public class AdaptiveRandomWordFactory extends RandomWordFactory {

    protected String wideCharacters;

    public void setWideCharacters(String wideCharacters) {
        this.wideCharacters = wideCharacters;
    }

    public AdaptiveRandomWordFactory() {
        characters = "absdegkmnopwx23456789";
        wideCharacters = "mw";
    }

    @Override
    public String getNextWord() {
        Random rnd = new Random();
        StringBuffer sb = new StringBuffer();
        StringBuffer chars = new StringBuffer(characters);
        int l = minLength + (maxLength > minLength ? rnd.nextInt(maxLength - minLength) : 0);
        for (int i = 0; i < l; i++) {
            int j = rnd.nextInt(chars.length());
            char c = chars.charAt(j);
            if (wideCharacters.indexOf(c) != -1) {
                for (int k = 0; k < wideCharacters.length(); k++) {
                    int idx = chars.indexOf(String.valueOf(wideCharacters.charAt(k)));
                    if (idx != -1) {
                        chars.deleteCharAt(idx);
                    }
                }
            }
            sb.append(c);
        }
        return sb.toString();
    }

}