Captcha.java

package railo.commons.img;

import java.awt.Font;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;

import javax.imageio.ImageIO;

/**
 * concrete captcha implementation
 */
public final class Captcha extends AbstractCaptcha {
	
	private static final char[] chars=new char[]{
		 'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'
		,'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'
		//,'0','1','2','3','4','5','6','7','8','9'
	};

	@Override
	public Font getFont(String font, Font defaultValue) {
		return Font.decode(font);
	}

	/**
	 * write out image object to a output stream
	 * @param image
	 * @param os
	 * @param format
	 * @throws IOException
	 */
	public static void writeOut(BufferedImage image, OutputStream os, String format) throws IOException {
		ImageIO.write(image, format, os);
		
	}

	/**
	 * creates a random String in given length
	 * @param length length of the string to create
	 * @return
	 */
	public static String randomString(int length) {
		StringBuilder sb=new StringBuilder();
		for(int i=0;i<length;i++) {
			sb.append(chars[AbstractCaptcha.rnd(0,chars.length-1)]);
		}
		return sb.toString();
	}
}